Bipolaris oryzae causes brown spot in rice (Oryza sativa) inflicting substantial grain yield losses worldwide. Knowledge of the population structure, genetic diversity and sexual recombination of the fungal pathogen can help to implement effective disease management strategies. In this study, B. oryzae isolates sampled from Iran, the Philippines and Japan were analysed with 12 simple-sequence repeat (SSR) markers, newly developed from the genome sequence of the fungus. Among the 288 B. oryzae isolates genotyped, 278 unique haplotypes were identified. High genotype numbers (richness) with even distribution (evenness) were found within the collection sites. Both mating types, MAT1-1 and MAT1-2, were present in each collection area, and the sexual state was induced under controlled conditions with production of viable ascospores. However, the tests of linkage disequilibrium rejected of the hypothesis of random mating. Discriminant analysis of principal components (DAPC) revealed that the B. oryzae collection formed three clusters, each consisting of isolates from different collection sites. Analysis of molecular variance (AMOVA) showed that genetic variation among clusters was 18.7%, with the rest of the variation distributed within clusters (R ST = 0.187, P < 0.001). Statistically significant pairwise genetic differentiation was found between the clusters. These results show that Asian B. oryzae isolates are genetically diverse, and, overall, distributed in three groups. These findings will be helpful in managing the disease and guide the use of representative isolates needed for selection of resistant rice varieties.

No abstract

BACKGROUND Pistachio fruits suffer from postharvest decay, caused by Aspergillus flavus. This results in aflatoxin B1 (AFB1) accumulation in kernels, which is hazardous for human health due to its carcinogenic activity. In this study, the mechanism used by exogenous β‐aminobutyric acid (BABA) treatment for attenuating Aspergillus decay, minimizing aflatoxin B1 (AFB1) accumulation, and maintaining nutritional quality in fresh‐in‐hull pistachio kernels, infected by A. flavus during storage at 25 °C for 18 days, was investigated. RESULT Results of an in vivo assay showed that the spore germination and germ tube elongation of A. flavus was repressed by BABA treatment at 7.5 mM. Aspergillus decay accompanied by AFB1 accumulation was also minimized in fresh‐in‐hull pistachio kernels treated with BABA at 7.5 mM and infected by A. flavus. Fresh‐in‐hull pistachio kernels, infected by A. flavus, treated with BABA at 7.5 mM, also exhibited higher phenol and flavonoid accumulation and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) scavenging capacity accompanied by higher phenylalanine ammonia lyase (PAL) enzyme activity. CONCLUSION Promoting phenylpropanoid pathway activity with higher PAL enzyme activity in fresh‐in‐hull pistachio kernels treated with BABA may not only reduce Aspergillus decay in kernels by cell wall fortification but also may be favorable for maintaining the kernels’ nutritional quality through its effects on ROS scavenging capacity. As oxidative stress, represented by ROS accumulation, is responsible for A. flavus growth and AFB1 accumulation, higher phenol and flavonoid accumulation in fresh‐in‐hull pistachio kernels treated with BABA may be beneficial for attenuating Aspergillus decay and minimizing AFB1 accumulation. © 2019 Society of Chemical Industry

Leaves of Sansevieria trifasciata with leaf blight symptoms were collected from greenhouses of Miyandoab, West Azerbaijan province, Iran, during the summer of 2016. Leaf blight symptoms were large, elongated and gray to pale brown with brown margins. Three single spore isolates were obtained from diseased leaves and the pathogenicity of each isolate to plants was confirmed by inoculation tests based on Koch's postulates. The pathogen was identified as Stemphylium vesicarium, based on both morphological characteristics and sequencing of the Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene. This is the first report of Stemphylium vesicarium causing leaf blight on Sansevieria trifasciata in Iran and the world.