Diabetes is one the world’s most widespread diseases, affecting over 327 million people and causing about 300,000 deaths annually. Despite great advances in prevention and therapy, existing ...treatments for this disorder have serious side effects. Plants used in traditional medicine represent a valuable source in the search for new medicinal compounds. Hamelia patens Jacq. has been used for treating diabetes and, so far, no reports have been made on the in vivo antihyperglycemic activity of this plant. The present study on H. patens aimed to test the antihyperglycemic effect of repeated administrations of the crude and fractional methanolic extracts (CME and FME, respectively) on rats with hyperglycemia induced by streptozotocin. After 10 administrations (20 days), each extract had lowered blood glucose to a normal level. The extracts produced effects similar to metformin. Of the five compounds identified by chromatographic analysis of the extracts, epicatechin and chlorogenic acid demonstrated antihyperglycemic effect. The antioxidant activity of the extracts was evidenced by their IC50 values (51.7 and 50.7 μg/mL, respectively). The LD50≥2000 mg/Kg suggests low toxicity for both CME and FME. Thus, considering that the antihyperglycemic and antioxidant effects of metformin and extracts from H. patens were comparable, the latter may be efficacious for treating diabetes.
The filamentous fungus Fusarium verticillioides is a widely distributed pathogen that causes ear, stalk and root rot of maize. This fungus also produces mycotoxins that accumulate in maize kernels. ...As chemical control has proven to be insufficient, new and effective disease control measures must be implemented. An improved understanding of the diversity of pathogen populations is thus crucial. Here, a set of 83 F. verticillioides isolates from a major maize-growing region of Mexico was characterized at the pathogenic and genetic diversity levels. A pathogenicity assay on maize seedlings established that all isolates were pathogenic and variable for aggressiveness, with most causing major damage on maize roots (>50% of root rotted). Genetic analysis also revealed high levels of variability, as seen by the high number of haplotypes (76), the population diversity value according to effective number of alleles (6.32), gene diversity (0.80), the polymorphic index content (0.78) and Shannon's information index (2.06). The analysed F. verticillioides population reproduces asexually, suggesting that the observed genetic and pathogenic diversity is not the result of sexual reproduction and is probably mediated by other evolutionary forces, such as mutation, gene flow, selection and hyphal anastomosis.
Wild sunflower is a common weed that grows among agricultural crops in many parts of the world, where it is both highly invasive and competitive and can serve as a reservoir for plant pathogens. ...Recently, signs of powdery mildew (PM) were observed on wild sunflower plants in Sinaloa, Mexico. The aim of this study was to identify the causal agent based on morphology and molecular techniques, and to determine pathogenicity on sunflower plants. Phylogenetic analysis of the ITS region grouped the sequences within lineage III of the genus Golovinomyces, which comprises pathogenic species of the plant tribe Heliantheae of Asteraceae. However, within this lineage, the three species belonging to this group: G. circumfusus, G. ambrosiae and G. spadiceus, cannot be differentiated based on the ITS region due to their close phylogenetic relationship. Morphometric analyses, particularly conidium size and germ tube morphology, confirmed the identity of the fungus infecting wild sunflowers as G. spadiceus. Inoculation tests under greenhouse conditions confirmed the pathogenicity of G. spadiceus in wild sunflower and in the commercial sunflower hybrid SYN3950HO. Signs of powdery mildew displayed on sunflower were similar to those observed under field conditions and in two independent inoculation tests. Our results confirm that wild sunflower is a potential source of G. spadiceus inoculum for commercial sunflower during the autumn-winter growing season.
The fungus
Macrophomina phaseolina
, the causal agent of charcoal rot of common beans, damages the roots, stems, and leaves of seedlings and plants and forms resistant structures, so that chemicals ...are not sufficient for disease control. Integrated management systems associated with the use of biological control techniques are a sustainable alternative. Here we collected 37 native bacterial isolates from the common bean rhizosphere and screened them for antagonistic activity against
M. phaseolina
. Four isolates (BA97, BN17, BN20, and BR20) identified as
Bacillus
spp. showed antagonism in vitro against
M. phaseolina
, inhibiting its growth by 62.5–85%. In an
in planta
antagonistic assay, isolate BN20 reduced disease severity the most. Isolates BA97, BN17, BN20, and BR20 produced volatile compounds as a mechanism of antagonism. They also produced indole acetic acid in vitro (1.98–3.87 μg/ml). These results suggest that seed bacterization with the rhizobacterial isolates for field planting may be an effective means to reduce crop damage by
M. phaseolina
.
Summary
Two rapid and simple in planta transformation methods have been developed for the model legume Medicago truncatula. The first approach is based on a method developed for transformation of ...Arabidopsis thaliana and involves infiltration of flowering plants with a suspension of Agrobacterium. The second method involves infiltration of young seedlings with Agrobacterium. In both cases a proportion of the progeny of the infiltrated plants is transformed. The transformation frequency ranges from 4.7 to 76% for the flower infiltration method, and from 2.9 to 27.6% for the seedling infiltration method. Both procedures resulted in a mixture of independent transformants and sibling transformants. The transformants were genetically stable, and analysis of the T2 generation indicates that the transgenes are inherited in a Mendelian fashion. These transformation systems will increase the utility of M. truncatula as a model system and enable large‐scale insertional mutagenesis. T‐DNA tagging and the many adaptations of this approach provide a wide range of opportunities for the analysis of the unique aspects of legumes.
A new disease on sesame (Sesamum indicum L.) plants was observed in the municipalities of Ahome, El Fuerte and Choix in the state of Sinaloa, Mexico during the summer of 2014. The disease occurred ...during the rainy season (August-September) when temperatures ranged between 27-40°C. The symptoms were lesions on leaves, petioles, stems and capsules. Up to 100% incidence was observed, and up to 50% of the foliage exhibited symptoms under field conditions. Isolations were made from leaves and a bacterium was consistently recovered on nutrient agar medium. Based on physiological and biochemical tests, as well as sequences from three different DNA regions, the bacterium was identified as Xanthomonas campestris pv. sesami. Pathogenicity tests confirmed the ability of select isolates to cause symptoms similar to those observed under field conditions.
We utilized the two-compartment system to study the effect of arsenic (As) on the expression of the
Glomus intraradices high-affinity phosphate transporter
GiPT, and the
GiArsA gene, a novel protein ...with a possible putative role as part of an arsenite efflux pump and similar to ArsA ATPase. Our results show that induction of
GiPT expression correlates with As(V) uptake in the extra-radical mycelium of
G. intraradices. We showed a time-concerted induction of transcript levels first of
GiPT, followed by
GiArsA, as well as the location of gene expression using laser microdissection of these two genes not only in the extra-radical mycelium but also in arbuscules. This work represents the first report showing the dissection of the molecular players involved in arbuscular mycorrhizal fungus (AMF)-mediated As tolerance in plants, and suggests that tolerance mediated by AMF may be caused by an As exclusion mechanism, where fungal structures such as the extra-radical mycelium and arbuscules may be playing an important role. Our results extend knowledge of the mechanisms underlying As efflux in arbuscular mycorrhizal fungi and mechanisms related to As tolerance.
► Molecular mechanism of arbuscular mycorrhiza-mediated As tolerance in plants. ► AM
GiPT and
GiArsA are induced in a time-concerted manner in response to arsenate. ► Laser microdissection shows
GiPT/
GiArsA expression in arbuscule-containing cells. ► Arsenate tolerance mediated by AMF may be caused by an As exclusion mechanism.
Background: Wetlands in Neotropics harbor high fungal diversity, including arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE). This study describes the interaction of plant roots ...with AMF and DSE in a freshwater wetland belonging to a hotspot of biodiversity.
Hypothesis: Differential root colonization between arbuscular mycorrhizal and dark septate endophyte fungi is influenced by plant species and abiotic conditions in a freshwater wetland.
Studied species: Plant species colonized by arbuscular mycorrhizal and dark septate endophyte fungi.
Methods: Properties of soils and the water column, floristic composition, root colonization by AMF and DSE, and molecular identification of AMF inside roots were studied.
Results: Soils were Gleysol and flooded during the rainy season. Most of identified plant species were herbaceous, with Cyperus articulatus and Mimosa pigra as the dominant species. Seven of 8 analyzed plant species exhibited differential co-colonization between AMF and DSE. Repeated sampling for one year under flooding/dry conditions demonstrated that C. articulatus and M. pigra were mainly associated with DSE and AMF, respectively. A positive correlation between dissolved O2 in the water column and fungal colonization was observed in C. articulatus . Glomerales and Archaeosporales were molecularly identified inside roots containing arbuscules of M. pigra .
Conclusions: Findings highlight differential coexistence between AMF and DSE in plant roots; fungal colonization was influenced by flooding/dry conditions in a neotropical wetland; the community of AMF inside arbusculated roots of M. pigra includes at least four clades.
Long-term successional dynamics of an inoculum of arbuscular mycorrhizal fungi (AMF) associated with the maize rhizosphere (from traditionally managed agroecosystems in Los Tuxtlas, Veracruz, ...Mexico), was followed in Bracchiaria comata trap cultures for almost eight years. The results indicate that AMF diversity is lost following long-term subculturing of a single plant host species. Only the dominant species, Claroideoglomus etunicatum, persisted in pot cultures after 13 cycles. The absence of other morphotypes was demonstrated by an 18S rDNA survey, which confirmed that the sequences present solely belonged to C. etunicatum. Members of Diversisporales were the first to decrease in diversity, and the most persistent species belonged to Glomerales.
The genetic variation of maize (Zea mays ssp. Mays L.) in Mexico has been studied especially in the south-central part of the country. The state of Sinaloa (first in production) has 23% of the ...national racial genetic variation, but its evaluation is scarce. We collected 144 samples of corn (Tuxpeno Norteno, Vandeno, Onaveno, Elotero de Sinaloa, Tabloncillo, Tablaoncillo Perla, Bofo, Jala, Blando de Sonora, Chapalote, Dulcillo del Noroeste and Reventador) in different state locations in order to describe relevant morphological and agronomic characteristics so as to determine a grouping pattern. The accessions were evaluated in two environments with a simple lattice design of 12*12, analyzing 27 variables. ANDEVA detected significant differences between accessions (for all variables), for the genotype * environ ment interaction (width/length of the grain) and for environments in spikes (length of branched section, number of primary branches and length of central branch), in cob (diameter/length, length of the peduncle and of the cob) and in grain (volume and weight/ volume). The first three main components (PCA) explained 64% of the variance, where the variables number of leaves, diameter and length of the cob; the width and thickness of the grain; grain width and length and flowering; are the most important. The graphic representation of the PCA (1 and 2) revealed six groups, and that of conglomerates five. Some accessions shared characteristics with more than one racial group and their position was close to that of those sharing characteristics. A wide genetic diversity of native corn is confirmed in Sinaloa.
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