Genetic diversity and population structure analysis of isolates of the rice false smut pathogen Ustilaginoidea virens in India

Genetic diversity assessment and population structure analysis are essential for characterization of pathogens and their isolates. Markers are essential tools for exploring genetic variation among the isolates. False smut of rice caused by Ustilaginoidea virens, formerly Villosiclava virens, is a major emerging disease of rice in India. A high level of variability is observed at the field level, but no information is available from India on genetic diversity and population structure. This is the first report of genetic diversity and population structure of U. virens from India that included 63 isolates distributed across the vast geographical area of eastern and north-eastern India (18.9 to 26.7°N and 82.6 to 94.2°E). Seventeen RAPDs and 14 SSRs were identified as polymorphic and a total of 140 alleles were detected across the populations. The average number of alleles per locus for each primer was 4.5. All the isolates were grouped into two major clusters, with partial geographical segregation that was supported by principal coordinate analysis. Mantel test suggested genetic distance within the isolates increased with increasing geographical distance. Analysis of molecular variation showed more genetic variation within populations and less among populations. This outcome will help in understanding genetic diversity of U. virens from eastern and north-eastern India and in planning effective management strategies.     

Mining of rice blast resistance gene Pi54 shows effect of single nucleotide polymorphisms on phenotypic expression of the alleles

The rice blast resistance gene Pi54 (formerly Pi-k ^h ) isolated from indica rice line Tetep confers broad spectrum resistance to different strains of Magnaporthe oryzae in India. In this study, we performed PCR based allele mining for blast resistance gene Pi54 from six cultivated rice lines and eight wild rice species to understand its structural variation and its impact on the phenotypes. Sequence analysis indicates presence of more variation between cultivated and wild species (35–90 %) than variation found among cultivated species (1–20 %). Structural analysis of alleles showed presence of variable number of Open Reading Frames (0–2) principally having point mutations in the leucine rich repeats (LRR) regions. The Ka/Ks ratio of LRR region was >1, which shows the effect of selection pressure at this domain. The Pi54 alleles have 142 polymorphic sites with average nucleotide diversity of 0.04522. The K_a/K_s ratio of coding region ranged from 0 to >1 and Tajima’s D test showed negative as well as Darwinian selection within the alleles, which corresponded well with their phenotypic reaction to M. oryzae. The results obtained in this study shows divergent nature of Pi54 allele in wild species and land races of rice. The resistance alleles identified in this study can be used in effective management of rice blast disease through gene pyramiding.     

An ethnobotanical survey of medicinal plants used by ethnic people in West and South district of Tripura,India

An ethno-medicinal investigation was conducted to highlights the traditional knowledge of medicinal plants being used by the tribe in West and South district of Tripura. This paper provides information about the different uses of plants used in their primary health care system. Tripura is a small north-eastern state of India and also a part of both Himalayan and Indo-Burma biodiversity region. It is a goldmine of medicinal plants and use of different plants in tribal traditional heath care systems has long history. Nineteen different tribes in Tripura, depend on natural resources at a great extent. This paper documented 113 medicinal plant species from 56 families along with their botanical name, local name, family name, habit, medicinal parts used, and traditional usage of application. The dominant families are Euphorbiaceae (7 species), Apocynaceae (6 species), Fabaceae and Rubiaceae (5 species each), Caesalpiniaceae, Asteraceae, Liliaceae and Verbenaceae (4 species each), Combretaceae, Labiatae, Malvaceae, Rutaceae and Zingiberaceae (3 species each). Tribes of Tripura have rich traditional knowledge on plant based medicine. Different parts of the plants in crude form/plant extracts/decoctions/infusion or pastes are employed in diverse veterinary and human diseases by the tribe’s of Tripura in daily life.     

Effects of high temperature on spikelet sterility in rice (Oryza sativa L.): association between molecular markers and allelic phenotypic effect in field condition

Genetic Resources and Crop Evolution - Rice varieties are generally bred for higher yield but may possess genomic regions conferring tolerance to abiotic stresses. Climate change driven heat stress...