Plant Biology

Two combinations (designated as options 1 and 2) of four plastid markers (matK, rpoC1, rpoB, psbA-trnH) that have been recommended for DNA barcoding were tested for utility in a putatively recently-diversified group: the primarily Canarian clade within the genus Tolpis (Asteraceae). Prior studies had indicated very little molecular variation in the group, and thus it was used to determine whether accepted taxa, segregate species, and morphological variants ostensibly deserving taxonomic recognition could be distinguished employing regions proposed as useful for DNA barcoding. The regions, particularly option 2, separated all morphologically distinct species of Tolpis except one, and distinguished one segregate species and certain variants in a morphologically variable and intergrading group (comprising both the T. laciniata and T. lagopoda species complexes). The barcoding sequences also revealed several variants that are worthy of additional study in order to further understand the diversity of Tolpis in the Canary Islands.

Two combinations (designated as options 1 and 2) of four plastid markers (matK, rpoC1, rpoB, psbA-trnH) that have been recommended for DNA barcoding were tested for utility in a putatively recently-diversified group: the primarily Canarian clade within the genus Tolpis (Asteraceae). Prior studies had indicated very little molecular variation in the group, and thus it was used to determine whether accepted taxa, segregate species, and morphological variants ostensibly deserving taxonomic recognition could be distinguished employing regions proposed as useful for DNA barcoding. The regions, particularly option 2, separated all morphologically distinct species of Tolpis except one, and distinguished one segregate species and certain variants in a morphologically variable and intergrading group (comprising both the T. laciniata and T. lagopoda species complexes). The barcoding sequences also revealed several variants that are worthy of additional study in order to further understand the diversity of Tolpis in the Canary Islands.

Economic Assessment of Morel (Morchella spp.) Foraging in Michigan. USA. Wildforaged mushrooms represent a natural resource that provides economic value to foragers through both market and nonmarket recreational channels. Despite the importance of non-timber forest resources for sustainable management of forestlands, little attention has been paid to who forages for wild mushrooms, why they choose to forage, where they go, and what economic value is generated. This report draws upon survey data from 78 foragers who are certified to sell their mushrooms and 85 noncertified foraging enthusiasts. Its goal is to understand foraging patterns and values for morels (Morchella spp.) in the State of Michigan (USA). Most foragers spend fewer than 10 days each year foraging, and those who sell their morels are most likely to sell to local restaurants, pubs and bars, and informally to their friends. Certified foragers who choose to sell their morels sell for an average price of $36 per pound ($36/lb) for fresh black or yellow morels. Costs to supply fresh morels ranged widely among the 16 certified sellers who reported full cost details; over 70% of morels were supplied at costs below $30/lb, but some certified sellers incurred costs in the hundreds of dollars per pound. Recreational morel gatherers paid $43 to $335 per trip of foraging morels, with a median value of $93 per trip. Morel foragers also search for other mushrooms with oyster mushrooms (Pleurtous spp.), chanterelles (Cantharellus spp), hen-of the-woods (Grifola frondosa), and chicken-of-the-woods (Laetiporus spp) being the most popular.

Economic Assessment of Morel (Morchella spp.) Foraging in Michigan. USA. Wildforaged mushrooms represent a natural resource that provides economic value to foragers through both market and nonmarket recreational channels. Despite the importance of non-timber forest resources for sustainable management of forestlands, little attention has been paid to who forages for wild mushrooms, why they choose to forage, where they go, and what economic value is generated. This report draws upon survey data from 78 foragers who are certified to sell their mushrooms and 85 noncertified foraging enthusiasts. Its goal is to understand foraging patterns and values for morels (Morchella spp.) in the State of Michigan (USA). Most foragers spend fewer than 10 days each year foraging, and those who sell their morels are most likely to sell to local restaurants, pubs and bars, and informally to their friends. Certified foragers who choose to sell their morels sell for an average price of $36 per pound ($36/lb) for fresh black or yellow morels. Costs to supply fresh morels ranged widely among the 16 certified sellers who reported full cost details; over 70% of morels were supplied at costs below $30/lb, but some certified sellers incurred costs in the hundreds of dollars per pound. Recreational morel gatherers paid $43 to $335 per trip of foraging morels, with a median value of $93 per trip. Morel foragers also search for other mushrooms with oyster mushrooms (Pleurtous spp.), chanterelles (Cantharellus spp), hen-of the-woods (Grifola frondosa), and chicken-of-the-woods (Laetiporus spp) being the most popular.

Studies on the distribution, epidemiology and pathogenesis of Cryptococcus neoformans on the island of Puerto Rico are few. We have studied mouse virulence and in vitro antifungal susceptibility of 133 isolates of C. neoformans: 121 environmental and 12 clinical (9 from AIDS patients), that were isolated in Puerto Rico. In experimental CD-1 mice infected intravenously, the mean lethal dose 50~o values (28 days) were > 5.2 • 106 and 1.1 x 105 cells/mouse for environmental and clinical isolates, respectively. Using an agar dilution assay, the minimum inhibitory concentrations of amphotericin B, ketoconazole and 5-fluorocytosine were comparable for environmental and clinical isolates in both yeast nitrogen dextrose base agar and Kimmig's agar. These data suggest a difference in lethality for mice, but no difference in antifungal susceptibility of environmental and clinical isolates of C. neoformans obtained in Puerto Rico.

The kinesin family is greatly expanded in plants compared with animals and, with more than a third up-regulated in expression during cell division, it has been suggested that this expansion facilitated complex plant-specific cytoskeletal rearrangements. The cell cycle-regulated kinesins include two with an N-terminal malectin domain, a protein domain that has been shown to bind polysaccharides and peptides when found extracellularly in receptor-like kinases. Although malectin domain kinesins are evolutionarily deep rooted, their function in plants remains unclear. Here we show that loss of MALECTIN DOMAIN KINESIN 2 (MDKIN2) results in stochastic developmental defects in pollen, embryo, and endosperm. High rates of seed abnormalities and abortion occur in mdkin2 mutants through a partial maternal effect. No additive effect or additional developmental defects were noted in mdkin1 mdkin2 double mutants. MDKIN2 is expressed in regions of cell division throughout the plant. Subcellular l...

Efficient Use of Nitrogen in Cropping Systems Efficient use of N in cropping systems is often viewed from agronomic, economic, or environmental perspectives. A given N management system may provide highly efficient use of N from one perspective but be relatively inefficient from another. This chapter reviews basic factors affecting N use efficiency (NUE) from agronomic, economic, and environmental perspectives and discusses interrelationships among these perspectives. The agronomic section reviews ways of characterizing NUE based on yield and N recovery in relation to N inputs and discusses physical potentials and limitations for improving these relationships. Since Chapt. 17 (this book) deals with the role of N in attaining high yield potentials, the agronomic section in this chapter emphasizes factors affecting the slope of yield curves rather than factors affecting maximum yield levels with a nonlimiting N rate. The economic section reviews factors that determine optimum N rates and discusses economic considerations for optimizing inputs (e.g., application practices and nitrification inhibitors) that affect the slope of yield curves. The environmental section examines relationships between N fertilizer recovery and environmental impact of N fertilizer use and also environmental implications of maximizing return from N fertilizer use. I. AGRONOMIC PERSPECTIVE A. Characterizing Efficiency The phrase N use efficiency (NUE) usually has referred to relationships between yield and N rate (yield efficiency), N recovered and N rate (N recovery efficiency), or yield and N recovered (physiological efficiency). For

From Schkuhria pinnata (Lam.) O. Ktze. var. pinnata we isolated two flavonoids, identified as 5, 7, 3', 4' -tetrahydroxi-6-methoxy flavonol and 5, 7, 3', 4'tetrahydroxi-3-methoxy flavone. Resides these we found ~-sitosterol, a-amirina lupeol and a mixture of lineal hydrocarbon. De la Schkuhria pinnata (Lam.) O. Ktze. var. pinnata, reportamos el aislamiento de dos flavonoides, caracterizando a uno de ellos como el 5, 7, 3'; 4' -tetrahidroxi-6-metoxiflavonol y proponiendo tentativamente al otro como 5, 7, 3', 4'-tetrahidroxi-3-metoxiflavona, además de los ya reportados ~-sitosterol, a-amirina, lupeol y una mezcla de hidrocarburos lineales C-27 a C-33. • La Schkhuria pinnata (Lam.) O. Ktze. var. pinnata, conocida comúnmente como "canchalagua" o "canchalahua", es una planta silvestre que crece en

From Schkuhria pinnata (Lam.) O. Ktze. var. pinnata we isolated two flavonoids, identified as 5, 7, 3', 4' -tetrahydroxi-6-methoxy flavonol and 5, 7, 3', 4'tetrahydroxi-3-methoxy flavone. Resides these we found ~-sitosterol, a-amirina lupeol and a mixture of lineal hydrocarbon. De la Schkuhria pinnata (Lam.) O. Ktze. var. pinnata, reportamos el aislamiento de dos flavonoides, caracterizando a uno de ellos como el 5, 7, 3'; 4' -tetrahidroxi-6-metoxiflavonol y proponiendo tentativamente al otro como 5, 7, 3', 4'-tetrahidroxi-3-metoxiflavona, además de los ya reportados ~-sitosterol, a-amirina, lupeol y una mezcla de hidrocarburos lineales C-27 a C-33. • La Schkhuria pinnata (Lam.) O. Ktze. var. pinnata, conocida comúnmente como "canchalagua" o "canchalahua", es una planta silvestre que crece en

Mangifera indica, commonly called mango, is an edible fruit that are also used for juice and wine production. Fresh leaves of M. indica were collected from the premises of Adekunle Ajasin University, Akungba Akoko Ondo State, Nigeria. Materials used, including Gram staining reagents, for the study are properly sterilized. Similarly, the culture media used, including Nutrient agar, MacConkey agar, Eosin methylene blue agar, Salmonella-Shigella agar, Mannitol salt agar, Mueller-Hinton agar and Nutrient broth, were properly sterilized. The bacterial isolates identified and used for the study were Staphylococcus aureus, Salmonella typhi Klebsiella spp., Pseudomonas aeruginosa, Escherichia coli, and Citrobacter spp. Antimicrobial susceptibility test of the Mango (Mangifera indica) leaves extract against the test bacteria shows that 200 mg/ml and 175 mg/ml extract of the plant source had observable effect against test organisms, particularly Escherichia coli, Salmonella typhi, and to a va...

Massarina ingoldiana occurs worldwide on a variety of dead plant substrates in aquatic habitats. This species has been accommodated in Massarina or Lophiostoma in Pleosporales, Dothideomycetes, but the validity of either of these taxonomic placements has not been confirmed with molecular data. In addition morphological variations occur among different populations of this species causing problems in identification. To evaluate the generic placement and monophyly of M. ingoldiana and the taxonomic usefulness of variable morphological features, phylogenetic analyses based on SSU and LSU sequences of ribosomal DNA were conducted for 10 putative strains of this species and its relatives. Phylogenies revealed that M. ingoldiana sensu lato is polyphyletic and comprises two distinct lineages within Pleosporales. Neither lineage was congeneric with either Massarina or Lophiostoma. Based on molecular data and a reevaluation of morphology, two new genera, Lindgomyces and Tingoldiago, are established for the two lineages of M. ingoldiana sensu lato. Lindgomyces includes four species, L. ingoldianus comb. nov. (5 M. ingoldiana sensu stricto), L. rotundatus sp. nov. (5 M. ingoldiana sensu lato), L. cinctosporae sp. nov. and L. breviappendiculatus comb. nov. (5 Lophiostoma breviappendiculatum). A new aquatic family, Lindgomycetaceae, is proposed for Lindgomyces and its sister taxon, Massariosphaeria typhicola. Isolates of a fungus from submerged Phragmites, with ascospores similar to those of M. ingoldiana, occurred in an additional single species lineage distant from that of M. ingoldiana (Lindgomyces). This fungus is described as Tingoldiago graminicola gen. & sp. nov. The discovery that Tingoldiago, which occurs in a lineage distantly related to Lindgomyces but has morphologically similar ascospores and ascospore sheaths, suggests that the elaborate ascospore sheath in M. ingoldiana has arisen in two separate lineages as a result of convergent evolution in response to the aquatic environment. The large gelatinous sheath previously was considered one of the most distinctive and stable features for species identification of M. ingoldiana.

A new ascomycete species, Natipusilla bellaspora, collected from submerged woody debris in a freshwater stream at Los Amigos Biological Station, Madre De Dios in the Peruvian Amazon is described and illustrated. This fungus is characterized by small, globose to subglobose, hyaline ascomata; small, globose to subglobose, eight-spored fissitunicate asci; one-septate, multiguttulate ascospores with two different gelatinous sheaths, an outer amorphous sheath that enlarges in water and an inner sheath that has a distinctive persistent shape and is attached to the ascospore apex. Morphologically N. bellaspora differs from other Natipusilla species in having larger ascospores and two ascospore sheaths. A second Natipusilla species, N. limonensis, is reported for the first time from Peru. Based on the unique morphological characters of taxa in Natipusilla and results of previous molecular phylogenetic analyses with other members of the Dothideomycetes, we establish Natipusillaceae fam. nov. for this unique tropical freshwater clade.

Massarina ingoldiana occurs worldwide on a variety of dead plant substrates in aquatic habitats. This species has been accommodated in Massarina or Lophiostoma in Pleosporales, Dothideomycetes, but the validity of either of these taxonomic placements has not been confirmed with molecular data. In addition morphological variations occur among different populations of this species causing problems in identification. To evaluate the generic placement and monophyly of M. ingoldiana and the taxonomic usefulness of variable morphological features, phylogenetic analyses based on SSU and LSU sequences of ribosomal DNA were conducted for 10 putative strains of this species and its relatives. Phylogenies revealed that M. ingoldiana sensu lato is polyphyletic and comprises two distinct lineages within Pleosporales. Neither lineage was congeneric with either Massarina or Lophiostoma. Based on molecular data and a reevaluation of morphology, two new genera, Lindgomyces and Tingoldiago, are established for the two lineages of M. ingoldiana sensu lato. Lindgomyces includes four species, L. ingoldianus comb. nov. (5 M. ingoldiana sensu stricto), L. rotundatus sp. nov. (5 M. ingoldiana sensu lato), L. cinctosporae sp. nov. and L. breviappendiculatus comb. nov. (5 Lophiostoma breviappendiculatum). A new aquatic family, Lindgomycetaceae, is proposed for Lindgomyces and its sister taxon, Massariosphaeria typhicola. Isolates of a fungus from submerged Phragmites, with ascospores similar to those of M. ingoldiana, occurred in an additional single species lineage distant from that of M. ingoldiana (Lindgomyces). This fungus is described as Tingoldiago graminicola gen. & sp. nov. The discovery that Tingoldiago, which occurs in a lineage distantly related to Lindgomyces but has morphologically similar ascospores and ascospore sheaths, suggests that the elaborate ascospore sheath in M. ingoldiana has arisen in two separate lineages as a result of convergent evolution in response to the aquatic environment. The large gelatinous sheath previously was considered one of the most distinctive and stable features for species identification of M. ingoldiana.

There is a growing demand for the efficient treatment of seaweed biomass and the production of seaweeddegrading enzymes. Fifteen algicolous fungi were isolated from the Red Sea macroalgae in Egypt and were studied for their capability of utilizing Sargassum and Palisada biomass and subsequent production of different thallus-degrading enzymes. Most of the fungi efficiently saccharified the macroalgal extracts that amounted to more than 70 % of the sugars in the unfermented macroalgal extract. Algicolous fungi fermented Sargassum through extracellular fucoidanases and alginases that were negatively correlated as revealed by principal component analysis (PCA), suggesting an antagonistic degradation of Sargassum polysaccharides. Extracellular agarases resulted in efficient fermentation of Palisada biomass. Fungi expressed also amylase and protease activities that were low or nonexistent and biomass-dependent.Amylase showed positive correlation with agarase as indicated by PCA, which suggests that the two enzymes synergistically degrade Palisada biomass. The enzymatic cocktails were also able to release reducing sugars from the powdered macroalgal thalli, indicating the importance of enzymes in the saprophytic growth of fungi. Generally, enzymatic activities and specific activities of fucoidanase, alginase, and agarase in algicolous fungi were higher than reported previously for non-algicolous fungi. Enzymatic activities of the marine brown algal pathogen Lindra thalassiae indicated that infection by this pathogen might occur through alginases. The results shed light into production of less expensive enzymatic mixtures from an understudied group of microorganisms targeting seaweeddegradation. These enzymes have many biotechnological and industrial applications as thallus maceration and protoplast isolation despite bioactivity of obtained oligosaccharides

Monographs are fundamental for progress in systematic botany. They are the vehicles for circumscribing and naming taxa, determining distributions and ecology, assessing relationships for formal classification, and interpreting long–term and short–term dimensions of the evolutionary process. Despite their importance, fewer monographs are now being prepared by the newer generation of systematic botanists, who are understandably involved principally with DNA data and analysis, especially for answering phylogenetic, biogeographic, and population genetic questions. As monographs provide hypotheses regarding species boundaries and plant relationships, new insights in many plant groups are urgently needed. Increasing pressures on biodiversity, especially in tropical and developing regions of the world, emphasize this point. The results from a workshop (with 21 participants) reaffirm the central role that monographs play in systematic botany. But, rather than advocating abbreviated models f...

 A bromovirus isolated from sunflower (Helianthus annuus L.) was characterised and shown to be highly related to Pelargonium zonate spot virus (PZSV), a virus reported in Italy, Spain, France, USA and Israel. Sunflower plants showing chlorotic concentric ring and linear pattern symptoms were observed near Paraná city (Entre Ríos Province) in commercial sunflower crops. This was the first observation of this type of symptoms in sunflower in Argentina, but similar ones have been reported in Africa and Mexico. The aim of this study was to characterize this new sunflower disease.  The characterization was based on virus transmission, host range, electron microscopy and comparison of its sequence with those of related viruses.  Virus transmission efficiency by mechanical inoculation to sunflower plants at the V2 vegetative stage was nearly 100%. Seed transmission was negative as plants derived from seeds of systemically infected plants showed no symptoms. A host range including 27 spe...

 Two potyviruses that infect sunflower (Helianthus annuus L.) crops have been reported in Argentina. Sunflower chlorotic mottle virus (SuCMoV) is the most widely distributed one, with two strains: common and ring spot, which have been completely characterized. Sunflower mild mosaic virus (SuMMoV) that produces a chlorotic mild mosaic on sunflower commercial crops was detected in the rural area of Paraná (Entre Ríos Province). This virus has been biologically and serologically characterized but not fully characterized at the molecular level. The aim of this work was to determine the complete sequence of SuMMoV and study its genomic organization.  A total RNA extraction was made from a preparation enriched with this virus. The quality of preparation was confirmed through electron microscopy and RT-PCR with specific primers for capsid protein gene. Total RNA obtained was pyrosequenced and the sequences obtained were analyzed.  Electron microscopy from rapid preparations of samples e...

This is the first survey to determine the occurrence, prevalence, and distribution of peanut (Arachis hypogaea) viral diseases in Argentina. It was conducted in the province of Córdoba, which has 92% of the country's peanut production. It included the main peanut viruses Peanut mottle virus (PeMoV), Peanut stripe virus (PStV), Cucumber mosaic virus (CMV), Peanut stunt virus (PSV), Tomato spotted wilt virus (TSWV), and Groundnut ringspot virus (GRSV). Leaf samples from 1,028 individual peanut plants with virus-like symptoms and 986 samples from asymptomatic plants were collected in six counties of Córdoba over 3 years and serologically tested for the presence of viruses. PeMoV was the most frequently detected virus, found in 58.8, 34.2, and 23.4% of samples from the 2003–04, 2004–05, and 2005–06 growing seasons, respectively, and it was found in all sampled counties. Also, it was the only virus detected in asymptomatic plants. Less than 4% of symptomatic plants were infected with...

, phosphorus (P), and potassium (K), are needed for site-specific crop management, where fertilizer nutrient application rates are adjusted spatially based on local requirements. This study reports on validation testing of a previously developed ion-selective electrode (ISE) based soil macronutrient sensing system using 36 soil samples from a single site, the Northern Illinois Agronomy Research Center (NIARC), and previously developed calibration models. Objectives were to (1) validate calibration models with a new array of membranes and electrodes, and ( ) evaluate the ability of the system to estimate variations in soil NO 3 -N, P, and K within a single test site. Soil extract samples were obtained using the Kelowna extractant. Electrode responses were measured with five ISEs for each of NO 3 -N, P, and K and were normalized using the baseline correction and two-point normalization methods developed in our previous work. The array of ISEs fabricated with new membranes and cobalt rod, in conjunction with the previously developed normalization methods and calibration models, accurately estimated NO 3 -N, P, and K in solution without need to recalibrate the ISE system through standard laboratory analysis of soil samples from the new test site. ISE-measured NO 3 -N, P, and K concentrations in Kelowna-based soil extracts were similar to those determined by standard instruments, validating the ability of the system to identify within-field macronutrient differences. The use of a calibration factor to adjust ISE measurements for the difference in extraction efficiency between Kelowna and standard extractants resulted in a slope near unity between soil NO 3 -N, P, and K concentrations determined by ISEs and standard methods. However, a relatively large offset in soil P concentration between calibrated ISEs and standard methods will require further investigation to identify the cause. This study showed that it was possible to transfer existing calibration equations to new membranes and electrodes through application of the baseline correction and two-point normalization methods and an adjustment for differences in extraction efficiency. This finding enhances the applicability of the ISEbased soil macronutrient sensing system and methodology for rapid soil analysis.

The new species Simira gardneriana M. R. Barbosa & A. L. Peixoto from northeastern Brazil is described. This is the first species of Sim¬ ira found in the "caatinga" vegetation. Simira Aublet (Rubiaceae, Rondeletieae) is a neotropical genus comprising about 40 tree species, ranging from Mexico to Brazil. Although a regional treatment of Simira from Brazilian Amazonia was recently published (Barbosa & Peixoto, 1989), the last comprehensive treatment of the genus for Bra¬ zil was that of Schumann (1889) for Flora Brasiliensis. During the study of collections of Rubiaceae from northeastern Brazil, this previously undescri¬ bed species was discovered by the first author.

Checklist of Rubiaceae of the state of Mato Grosso do Sul, Brazil. A list of the species of Rubiaceae of the state of Mato Grosso do Sul is presented, which includes 162 species in 51 genera. Compared to the list of species known for the fl ora of Brazil, Mato Grosso do Sul has 11.6% of the species known from the whole country. The most diverse genera are Borreria G.Mey. Galianthe Griseb. and Psychotria L., with 17, 16 and 14 species each. Nine species are new occurrences for the state.

Extracts of 32 plants from the Brazilian northeastern semi-arid region called Caatinga were evaluated through DPPH radical scavenging assay, β-carotene bleaching, and brine shrimp lethality tests (BST). Among the extracts studied Byrsonima cf. gardneriana, Mascagnia coriacea, Cordia globosa, Diodia apiculata and Hypenia salzmannii showed the highest activities in DPPH radical scavenging test. In the β-carotene bleaching test the highest activities were observed for Passiflora cincinnata, Chamaecrista repens, B. cf. gardneriana, Rollinia leptopetala, Serjania glabrata, Diospyros gaultheriifolia, C. globosa, Mimosa ophtalmocentra, M. coriacea and Lippia cf. microphylla. In contrast, R. leptopetala, Zornia cf. brasiliensis and Leonotis nepetifolia were the most active species in the BST.

e ilustrada. Próxima de Coussarea nodosa (Benth.) Müll. Arg., difere desta pelas folhas elípticas, pedúnculo da inflorescência com mais de 2,5 cm de comprimento, tirsos não umbeliformes, corola hipocrateriforme e o epicarpo do fruto de coloração castanho-dourado quando maduro.

Background and Objective: At the beginning of planting dragon fruit, seedlings often have decay at the base of the stem caused by the fungus Sclerotium rolfsii (S. rolfsii) Sacc. This disease is very detrimental for dragon fruit farmers. An alternative control of this disease may also use biological antagonistic microbes. The aim of this research was to evaluate Pseudomonas fluorescens (P. fluorescens) P60 against Sclerotium rolfsii in dragon fruit seedlings and its plant growth-promoting ability. Methodology: Experiments were conducted for the dragon fruit plantations of Agrowisata Kusumo Wanadri at Glagah Village, Temon Subdistrict, KulonProgo Regency. There were five treatments which includes: 1: Untreated control, 2: P. fluorescens P60 as a drench, 3: P. fluorescens P60 as a soak, 4: P. fluorescens P60 as a soak and drench and 5: Benomyl as a soak and drench. There were six replicates of each treatment and arranged in a randomized complete block design. The soak and drench were repeated six times, each for 10 min, 30 days after planting. Following the treatments, the following parameters were evaluated such as disease incidence, late populations of S. rolfsii, plant fresh weight, root length, number of shoots, the shoot length and qualitative phenolic compound contents. Data were analyzed by F-test to determine the effect of treatment. Results: This study results showed that the use of P. fluorescens P60 effectively suppress stem rot caused by S. rolfsii on dragon fruit seedlings, by inhibiting the incubation period as 29.76%, lower the disease intensity as 66.65%, suppress the disease incidence of 46.14%, lower late sclerotia population of 74.79% and increase the content of phenolic compounds qualitatively. The application of P. fluorescens P60 was most appropriate to the nursery dragon fruit cuttings material by soaking in a solution of P. fluorescens P60 for 10 min. Conclusion: The use of P. fluorescens P60 can promote the growth of dragon fruit seedlings, covering the difference in seedlings fresh weight of 52.87%, root length as 40.09%, number of shoots as 34.76% and long shoots as 8.99%.

Siliceous frustules of diatom algae contain unique long-chain polyamines, including those having more than six nitrogen atoms. These polyamines participate in the formation of the siliceous frustules of the diatoms but their precise physiological role is not clear. The main hypotheses include formation of a polyamine and polyphosphate supramolecular matrix. We have synthesized novel fluorescent dyes from a synthetic oligomeric mixture of polyamines and the fluorophore 7-nitro-2,1,3-benzoxadiazole. The long polyamine chain ensures the high affinity of these dyes to silica, which allows their application in the staining of siliceous materials, such as valves of diatom algae and fossilized samples from sediments. The fluorescently stained diatom valves were found to be promising liquid flow tracers in hydrodynamic tests. Furthermore, complexation of the polyamine component of the dyes with carbonic polymeric acids results in changes to the visible spectrum of the fluorophore, which allows study of the stability of the complex vs the length of the polyamine chain. Using poly (vinyl phosphonic acid) as a model for phosphate functionality in silaffins (a potential matrix in the formation of biogenic silica) little complexation with the polyamine fluorophores was observed, bringing into question the role of a polyamine -polymeric phosphate matrix in biosilicification.

Background The incorporation of silica within the plant cell wall has been well documented by botanists and materials scientists; however, the means by which plants are able to transport silicon and control its polymerization, together with the roles of silica in situ, are not fully understood. † Recent Progress Recent studies into the mechanisms by which silicification proceeds have identified the following: an energy-dependent Si transporter; Si as a biologically active element triggering natural defence mechanisms; and the means by which abiotic toxicities are alleviated by silica. A full understanding of silica formation in vivo still requires an elucidation of the role played by the environment in which silica formation occurs. Results from in-vitro studies of the effects of cell-wall components associated with polymerized silica on mineral formation illustrate the interactions occurring between the biomolecules and silica, and the effects their presence has on the mineralized structures so formed. † Scope This Botanical Briefing describes the uptake, storage and function of Si, and discusses the role biomolecules play when incorporated into model systems of silica polymerization as well as future directions for research in this field.

Resumen PANTI, Carolina; CESARI, Silvia N.; MARENSSI, Sergio A. y OLIVERO, Eduardo B.. Una nueva especie fósil de Araucaria del Paleógeno de Tierra del Fuego, Argentina. Ameghiniana [online]. 2007, vol. 44, n. 1, pp. 215-222. ISSN 1851-8044.

Treatment of tobacco (Nicotiana tabacum L.) plants with lithium induces the formation of necrotic lesions and leaf curling as in the case of incompatible pathogen interactions. Further similarities at the molecular level include accumulation of ethylene and of salicylic and gentisic acids, and induced expression of pathogenesis-related PR-P, PR5 and PR1 genes. With the exception of PR1 induction, lithium produced the same effects in transgenic tobacco plants that do not accumulate salicylate because of overexpression of the bacterial hydroxylase gene nahG. On the other hand, inhibition of ethylene biosynthesis with aminoethoxyvinylglycine prevented lithium-induced cell death and PR5 expression. These results suggest that lithium triggers a hypersensitive-like response where ethylene signalling is essential.

Large parts of the south-western Atlantic soft bottom intertidals are inhabited by the burrowing crab Neohelice granulata (previously known as Chasmagnathus granulatus) and the mud crab Cyrtograpsus angulatus, but adults rarely coexist in the same microhabitat. We describe the influence of burrows of N. granulata on the recruitment dynamic of C. angulatus and the effects of different ontogenetic stages of N. granulata on survival of recruits of C. angulatus. A two summer sampling shows that N. granulata burrows facilitate settlement of both species. To evaluate the mortality of recruits inside burrows, we performed a field experiment with juvenile and adult crab exclusion cages and inclusion of juveniles or adults of N. granulata. The results showed differences in crab sizes between treatments, due to predatory interactions that depended on prey size. When only juveniles of N. granulata were present, the higher mortality of C. angulatus was observed in smaller crabs. However when ad...

Questions: Do current models that predict shifting effects of herbivores on plant diversity with varying nutrient conditions apply to stressful systems like salt marshes? Do herbivores affect different components of the diversity as nutrient availability varies? Location: Salt marsh-salty steppe transition zone at the SW Atlantic Mar Chiquita coastal lagoon (37144 0 52 00 S, 57126 0 6 00 W), Argentina. We experimentally evaluated the separate and interactive effect of nutrients and rodent (Cavia aperea) herbivory, using exclosures and applying fertilizer (mostly nitrogen), following a factorial design in 50 cm  50 cm plots. Results: We found a negative effect of herbivory on diversity in the resourcepoor scenario (due to a reduction in species richness), but a positive effect when nutrients were added, by reducing the abundance of the dominant plant (and hence increasing evenness). Our experimental results contribute to the limited factorial evidence evaluating the role of nutrients and herbivory on the diversity of terrestrial plant communities, even in highly stressful environments like salt marsh-salty steppe transition zones. Our results also support the model that predicts negative effects of herbivores on plant diversity in low-nutrient conditions and positive effects in nutrient-enriched scenarios, and also support the mechanism assumed to act in these situations.

Show simple item record Physiological traits associated with drought resistance in Andean and Mesoamerican genotypes of common bean (Phaseolus vulgaris L.) dc.contributor.author Polania, Jose Arnulfo dc.contributor.author Rao, Idupulapati M. dc.contributor.author Cajiao, César dc.contributor.author Rivera, Mariela dc.contributor.author raatz, bodo dc.contributor.author Beebe, Stephen E. dc.date.accessioned 20160408T21:46:16Z dc.date.available 20160408T21:46:16Z dc.date.issued 20160406 dc.identifier.citation

Heat stress is a major limitation to grain yield in common bean (Phaseolus vulgaris L.). Tepary bean (Phaseolus acutifolius A. Gray) is better adapted to heat stress than common bean. Ten tepary bean accessions, four common bean genotypes and four interspecific lines involving P. vulgaris and P. acutufolius, P. coccineus and P. dumosus were evaluated for tolerance to heat stress conditions induced under greenhouse conditions and these were compared to plants grown under ambient temperatures. The high temperature treatment was 29 ±5 °C during the day and was >24 °C (up to 27 °C) during the night, while the ambient temperature (AT) treatment was 25 ±5 °C during the day and 19± 2 °C at night. The genotypic differences were evaluated for morpho-physiological characteristics of shoot and root and also yield components. The Genotype and Genotype × Temperature interactions were significant for all shoot and root morpho-physiological characteristics evaluated. Higher temperature (HT) sig...

Background: Common bean is the most important staple grain legume for direct human consumption and nutrition. It complements major sources of carbohydrates, including cereals, root crop, or plantain, as a source of dietary proteins. It is also a significant source of vitamins and minerals like iron and zinc. To fully play its nutritional role, however, its robustness against stresses needs to be strengthened. Foremost among these is drought, which commonly affects its productivity and seed quality. Previous studies have shown that photosynthate remobilization and partitioning is one of the main mechanisms of drought tolerance and overall productivity in common bean. Results: In this study, we sought to determine the inheritance of pod harvest index (PHI), a measure of the partitioning of pod biomass to seed biomass, relative to that of grain yield. We evaluated a recombinant inbred population of the cross of ICA Bunsi and SXB405, both from the Mesoamerican gene pool, to determine the effects of intermittent and terminal drought stresses on the genetic architecture of photosynthate allocation and remobilization in pods of common bean. The population was grown for two seasons, under well-watered conditions and terminal and intermittent drought stress in one year, and well-watered conditions and terminal drought stress in the second year. There was a significant effect of the water regime and year on all the traits, at both the phenotypic and QTL levels. We found nine QTLs for pod harvest index, including a major (17% of variation explained), stable QTL on linkage group Pv07. We also found eight QTLs for yield, three of which clustered with PHI QTLs, underscoring the importance of photosynthate remobilization in productivity. We also found evidence for substantial epistasis, explaining a considerable part of the variation for yield and PHI. Our results highlight the genetic relationship between PHI and yield and confirm the role of PHI in selection of both additive and epistatic effects controlling drought tolerance. These results are a key component to strengthen the robustness of common bean against drought stresses.

Nitrogen (N) accumulation in legumes is one of the main determinants of crop yield. Although N accumulation from symbiotic nitrogen fixation or N absorption from the soil has been widely investigated, there is no clear consensus on timing of the beginning of N accumulation and the termination of N accumulation and the physiological events that may be associated with these two events. The analyses conducted in this study aimed at identifying the determinant of N accumulation in two grain legume species. Nitrogen accumulation dynamics and mass accumulation and development stages were recorded in the field for several genotypes of common bean (Phaseolus vulgaris) and faba bean (Vicia faba) under different growing conditions. This study showed that during the vegetative stages, N accumulation rate was correlated with mass accumulation rate. However, the maximum accumulation of N did not correspond to the time of the maximum mass accumulation. In fact, for both species, N accumulation wa...

Improving adaptation to drought stress in white pea bean (Phaseolus vulgaris L.): Genotypic effects on grain yield, yield components and pod harvest index The International Center for Tropical Agriculture (CIAT) believes that open access contributes to its mission of reducing hunger and poverty, and improving human nutrition in the tropics through research aimed at increasing the eco-efficiency of agriculture. CIAT is committed to creating and sharing knowledge and information openly and globally. We do this through collaborative research as well as through the open sharing of our data, tools, and publications.

Plants depend on their root systems to acquire the water and nutrients necessary for their survival in nature, and for their yield and nutritional quality in agriculture. Root systems are complex and a variety of root phenes have been identified as contributors to adaptation to soils with low fertility and aluminium (Al) toxicity. Phenotypic characterization of root adaptations to infertile soils is enabling plant breeders to develop improved cultivars that not only yield more, but also contribute to yield stability and nutritional security in the face of climate variability. In this review the adaptive responses of root systems to soils with low fertility and Al toxicity are described. After a brief introduction, the purpose and focus of the review are outlined. This is followed by a description of the adaptive responses of roots to low supply of mineral nutrients [with an emphasis on low availability of nitrogen (N) and phosphorus (P) and on toxic levels of Al]. We describe progre...

Common bean (Phaseolus vulgaris L.) yields are severely limited by abiotic stresses, including drought and aluminum toxicity. Work at CIAT (the International Center for Tropical Agriculture) seeks to develop resistance to these stresses, employing both intraspecific and interspecific genetic variability. The analysis of physiological mechanisms is more advanced in the case of drought. Although deep rooting offers access to more moisture, as evidenced by higher values of stomatal conductance and canopy temperature depression, in many genotypes this does not result in greater yield. Photosynthate partitioning to grain plays a major role in drought resistance. Partitioning has been quantified as pod partitioning index (pod biomass at harvest as a percent of total biomass at mid-pod fill), and pod harvest index (grain as percent of total pod biomass). Both parameters consistently present significant correlations with yield under stress. Pod harvest index measured in a drought trial also...

Background and Aims Aluminium (Al) resistance in common bean is known to be due to exudation of citrate from the root after a lag phase, indicating the induction of gene transcription and protein synthesis. The aims of this study were to identify Al-induced differentially expressed genes and to analyse the expression of candidate genes conferring Al resistance in bean. † Methods The suppression subtractive hybridization (SSH) method was used to identify differentially expressed genes in an Al-resistant bean genotype ('Quimbaya') during the induction period. Using quantitative real-time PCR the expression patterns of selected genes were compared between an Al-resistant and an Al-sensitive genotype ('VAX 1') treated with Al for up to 24 h. † Key Results Short-term Al treatment resulted in up-regulation of stress-induced genes and down-regulation of genes involved in metabolism. However, the expressions of genes encoding enzymes involved in citrate metabolism were not significantly affected by Al. Al treatment dramatically increased the expression of common bean expressed sequence tags belonging to the citrate transporter gene family MATE (multidrug and toxin extrusion family protein) in both the Al-resistant and -sensitive genotype in close agreement with Al-induced citrate exudation. † Conclusions The expression of a citrate transporter MATE gene is crucial for citrate exudation in common bean. However, although the expression of the citrate transporter is a prerequisite for citrate exudation, genotypic Al resistance in common bean particularly depends on the capacity to sustain the synthesis of citrate for maintaining the cytosolic citrate pool that enables exudation.

This chapter was originally published in the book Advances in Agronomy, Vol. 114 published by Elsevier, and the attached copy is provided by Elsevier for the author's benefit and for the benefit of the author's institution, for non-commercial research and educational use including without limitation use in instruction at your institution, sending it to specific colleagues who know you, and providing a copy to your institution's administrator.

Background Agriculture is the single largest geo-engineering initiative that humans have initiated on planet Earth, largely through the introduction of unprecedented amounts of reactive nitrogen (N) into ecosystems. A major portion of this reactive N applied as fertilizer leaks into the environment in massive amounts, with cascading negative effects on ecosystem health and function. Natural ecosystems utilize many of the multiple pathways in the N cycle to regulate N flow. In contrast, the massive amounts of N currently applied to agricultural systems cycle primarily through the nitrification pathway, a single inefficient route that channels much of this reactive N into the environment. This is largely due to the rapid nitrifying soil environment of present-day agricultural systems. † Scope In this Viewpoint paper, the importance of regulating nitrification as a strategy to minimize N leakage and to improve N-use efficiency (NUE) in agricultural systems is highlighted. The ability to suppress soil nitrification by the release of nitrification inhibitors from plant roots is termed 'biological nitrification inhibition' (BNI), an active plant-mediated natural function that can limit the amount of N cycling via the nitrification pathway. The development of a bioassay using luminescent Nitrosomonas to quantify nitrification inhibitory activity from roots has facilitated the characterization of BNI function. Release of BNIs from roots is a tightly regulated physiological process, with extensive genetic variability found in selected crops and pasture grasses. Here, the current status of understanding of the BNI function is reviewed using Brachiaria forage grasses, wheat and sorghum to illustrate how BNI function can be utilized for achieving low-nitrifying agricultural systems. A fundamental shift towards ammonium (NH 4 + )-dominated agricultural systems could be achieved by using crops and pastures with high BNI capacities. When viewed from an agricultural and environmental perspective, the BNI function in plants could potentially have a large influence on biogeochemical cycling and closure of the N loop in crop -livestock systems.

Contents 1. Introduction: Agricultural and Soil Fertility Issues in the High Andes 126 1.1. Cropping systems of the Andes 126 1.2. Biophysical limitations and risks 127 1.3. Socioeconomic and cultural setting of Andean agriculture 129 1.4. Current challenges and emerging threats 131 1.5. Ecologically based intensification in the Andean context 132 2. Examining Soil Fertility and Management Strategies in Smallholder Systems 133 2.1. General concept of soil fertility 133 2.2. Approaches to examining soil fertility 133 3. Additional Considerations for Soil Fertility Interventions 162 3.1. Need to incorporate co-limiting crop growth factors 162 3.2. Integrating local needs and knowledge into soil fertility research 162 4. Conclusions and Recommendations 163 4.1. Outlook for agroecological intensification in the Andean context 163 4.2. Recommendations for future research and interventions 165 Acknowledgments 166 References 166

Nitrification, the biological oxidation of ammonium to nitrate, weakens the soil's ability to retain N and facilitates N-losses from production agriculture through nitrate-leaching and denitrification. This process has a profound influence on what form of mineral-N is absorbed, used by plants, and retained in the soil, or lost to the environment, which in turn affects N-cycling, N-use efficiency (NUE) and ecosystem health and services. As reactive-N is often the most limiting in natural ecosystems, plants have acquired a range of mechanisms that suppress soil-nitrifier activity to limit N-losses via N-leaching and denitrification. Plants' ability to produce and release nitrification inhibitors from roots and suppress soil-nitrifier activity is termed 'biological nitrification inhibition' (BNI). With recent developments in methodology for insitu measurement of nitrification inhibition, it is now possible to characterize BNI function in plants. This review assesses the current status of our understanding of the production and release of biological nitrification inhibitors (BNIs) and their potential in improving NUE in agriculture. A suite of genetic, soil and environmental factors regulate BNI activity in plants. BNI-function can be genetically exploited to improve the BNI-capacity of major food-and feed-crops to develop next-generation production systems with reduced nitrification and N 2 O emission rates to benefit both agriculture and the environment. The feasibility of such an approach is discussed based on the progresses made.

The tropical pasture grass Brachiaria humidiola (Rendle) Schweick releases nitrification inhibitory compounds from its roots, a phenomenon termed 'biological nitrification inhibition' (BNI). We investigated the influence of root exudates of B. humidicola on nitrification, major soil microorganisms and plant growth promoting microorganisms using two contrasting soil types, Andosol and Cambisol. The addition of root exudates (containing BNI activity that is expressed in Allylthiourea unit (ATU) was standardized in a bioassay against a synthetic inhibitor of nitrification, allylthiourea, and their function in soil was compared to inhibition caused by the synthetic nitrification inhibitor dicyandiamide. At 30 and 40 ATU g )1 soil, root exudates inhibited nitrification by 95% in fresh Cambisol after 60 days. Nitrification was also similarly inhibited in rhizosphere soils of Cambisol where B. humidicola was grown for 6 months. Root exudates did not inhibit other soil microorganisms, including gram-negative bacteria, total cultivable bacteria and fluorescent pseudomonads. Root exudates, when added to pure cultures of Nitrosomonas europaea, inhibited their growth, but did not inhibit the growth of several plant growth promoting microorganisms, Azospirillum lipoferum, Rhizobium leguminosarum and Azotobacter chroococcum. Our results indicate that the nitrification inhibitors released by B. humidicola roots inhibited nitrifying bacteria, but did not negatively affect other major soil microorganisms and the effectiveness of the inhibitory effect varied with soil type.

The Brachiaria hybrid cv. Mulato is well adapted to low-fertility acid soils deficient in phosphorus (P). To study the grassy forage's mechanisms for tolerating low P supply, we compared it with rice (Oryza sativa L. cv. Kitaake). We tested by using nutrient solution cultures, and quantified the effects of P deficiency on the enzymatic activities of phosphohydrolases and on carbon metabolism in P-deficient leaves. While P deficiency markedly induced activity of phosphohydrolases in both crops, the ratio of inorganic phosphorus to total P in leaves was greater in Brachiaria hybrid. Phosphorus deficiency in leaves also markedly influenced the partitioning of carbon in both crops. In the Brachiaria hybrid, compared with rice, the smaller proportion of 14 C partitioned into sugars and the larger proportion into amino acids and organic acids in leaves coincided with decreased levels of sucrose and starch. Hence, in Pdeficient leaves of the Brachiaria hybrid, triose-P was metabolized into amino acids or organic acids. Results thus indicate that the Brachiaria hybrid, compared with rice, tolerates low P supply to leaves by enhancing sugar catabolism and by inducing the activity of several phosphohydrolases. This apparently causes rapid P turnover and enables the Brachiaria hybrid to use P more efficiently.

Drought is a major constraint to common bean (Phaseolus vulgaris L.) production, especially in developing countries where irrigation for the crop is infrequent. The Mesoamerican genepool is the most widely grown subdivision of common beans that include small red, small cream and black seeded varieties. The objective of this study was to develop a reliable genetic map for a Mesoamerican 9 Mesoamerican drought tolerant 9 susceptible cross and to use this map to analyze the inheritance of yield traits under drought and fully irrigated conditions over 3 years of experiments. The source of drought tolerance used in the cross was the cream-seeded advanced line BAT477 crossed with the small red variety DOR364 and the population was made up of recombinant inbred lines in the F5 generation. Quantitative trait loci were detected by composite interval mapping for the traits of overall seed yield, yield per day, 100 seed weight, days to flowering and days to maturity for each field environment consisting of two treatments (irrigated and rainfed) and lattice design experiments with three repetitions for a total of six environments. The genetic map based on amplified fragment length polymorphism and random amplified polymorphic DNA markers was anchored with 60 simple sequence repeat (SSR) markers and had a total map length of 1,087.5 cM across 11 linkage groups covering the whole common bean genome with saturation of one marker every 5.9 cM. Gaps for the genetic map existed on linkage groups b03, b09 and b11 but overall there were only nine gaps larger than 15 cM. All traits were inherited quantitatively, with the greatest number for seed weight followed by yield per day, yield per se, days to flowering and days to maturity. The relevance of these results for breeding common beans is discussed in particular in the light of crop improvement for drought tolerance in the Mesoamerican genepool.