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Brown spot disease, caused by Bipolaris oryzae , is one of the several disastrous diseases affecting rice. The brown spot fungus illustrates substantial pathogenic and genetic variability. To the best of our knowledge, extensive analysis utilizing specific SSR primers for B. oryzae genome is quite inadequate for the population structure and genetic diversity of Indian B. oryzae isolates. A total of 84 brown spot isolates were collected from rice-cultivating areas across southern and eastern Indian states, viz., Tamil Nadu, Andhra Pradesh, Odisha and Chhattisgarh. The pathogenicity and virulence characteristics of these isolates were assessed with the susceptible cultivar CR Dhan 201. Twelve genome-specific SSR markers of B. oryzae warranted the investigation of the population structure and genetic diversity among the isolates. These isolates were categorized based on their disease grade as highly virulent isolates (4 nos.), virulent isolates (8 nos.), moderately virulent isolates (47 nos.) and less virulent isolates (25 nos.). PCR amplification and DNA sequencing confirmed the isolates to be B. oryzae. PCR amplification and DNA sequencing confirmed the isolates to be B. oryzae. The SSR markers produced a total of 35 alleles with 1 to 4 alleles per locus with a gene diversity ranging between 0.00 and 0.687 and a major allele frequency variation of 0.425-0.975. The PIC value ranged from 0.00 to 0.638 having a mean value of 0.34. Cluster analysis technique was applied to group the brown spot isolates into four distinct clusters. Principal coordinate and structure analysis identified two genetic clusters of B. oryzae isolates for individual states with some degree of distinctness complying with their virulence. Analysis of molecular variance revealed more genetic variation within populations and less among populations. The study outcome would expedite the comprehension of genetic diversity of  B. oryzae across the southern and eastern states of India. Furthermore, we anticipate its guidance in the development of more effective disease management strategies as well as in the generation of novel resistant varieties through marker-assisted breeding., Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-022-03347-4., Competing Interests: Conflict of interestAll the authors declare that they have no conflict of interest., (© King Abdulaziz City for Science and Technology 2022, Springer Nature or its licensor holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.)

False smut disease of rice caused by Ustilaginoidea virens, is an emerging threat to rice cultivation worldwide due to its detrimental effects on grain yield and quality. False smut disease severity was 4.44‒17.22% during a roving survey in Kharif 2016 in the four different rice ecosystems of Karnataka, India. Further, 15 pathogen isolates representing four different ecosystems were studied for their virulence and morphometric diversity. Among the 15 strains studied, most virulent strains Uv-Gvt was selected for whole genome sequencing in Illumina NextSeq 500 platform using 2 × 150 bp sequencing chemistry. The total assembled genome of Uv-Gvt was 26.96 Mb, which comprised of 9157 scaffolds with an N50 value of 15,934 bp and 6628 protein-coding genes. Next, the comparative genomic study revealed a similar gene inventory as UV-8b and MAFF 236576 strains reported from China and Japan, respectively. But, 1756 genes were unique to Uv-Gvt strain. The Uv-Gvt genome harbors 422 putative host-pathogen interacting genes compared to 359 and 520 genes in UV-8b and MAFF 236576 strains, respectively. The variant analysis revealed low genetic diversity (0.073‒0.088%) among U. virens strains. Further, phylogenetic analysis using 250 single copy orthologs genes of U. virens revealed a distinct phylogeny and an approximate divergence time. Our study, report the genomic resource of rice false smut pathogen from India, where the disease originated, and this information will have broader applicability in understanding the pathogen population diversity., Competing Interests: Conflict of interestThe authors declare that they have no conflict of interest in the publication., (© King Abdulaziz City for Science and Technology 2020.)

During the course of survey, an incidence of 7.14-90% of apple mosaic disease (AMD) was recorded in apple orchards in Jammu and Kashmir among various commercially grown cultivars. The maximum incidence of mosaic disease was observed in cultivar Golden Delicious. In addition to mosaic, symptoms of chlorosis, necrosis and ring spots were also observed. In the present study association of Apple necrotic mosaic virus (ApNMV) was confirmed by RT-PCR and sequencing of whole coat protein gene in samples tested negative for Apple mosaic virus (ApMV) in DAS-ELISA. Out of 18 samples tested in RT-PCR, ten were found positive for ApNMV. Out of ten ApNMV positive samples, amplicon of 680 bp of samples representing five cultivars were sequenced and sequence analysis showed 89-91% sequence identity with ApNMV. The phylogenetic analysis grouped Indian isolates into two sub-clusters under one major cluster (ApNMV group). The sub-cluster-I, included ApNMV isolates from cultivars, Oregon Spur, Red Delicious and Fuji Aztec along with Chinese and Korean isolates. Sub-cluster-II included ApNMV isolates associated with Golden Delicious and Royal Delicious. The comparison of coat protein gene-based sequence identity matrix showed maximum and minimum similarity of 89-99% with ApNMV isolates from China. It also showed maximum identity with PNRSV (61.6%) and ApMV (52.8%) under subgroup 3 of genus Illarvirus . Our study indicates that the ApNMV is commonly associated with AMD in India and may be a major cause of the mosaic disease in apple cultivars. To the best of our knowledge, this is the first report of the association of ApNMV with apple mosaic disease from India., Competing Interests: Conflict of interestAuthors declare no conflict of interest., (© King Abdulaziz City for Science and Technology 2020.)

The main aim of this study is to assess the potentiality of SSR markers for the identification of the cross-species transferability frequency in a large set of the diverse genome types of wild relative rice along with cultivated rice. Here, we used 18 different rice genotypes representing nine different genome types with 70 SSR markers to investigate the potentiality of cross-species transferability rate. The overall cross-species transferability of SSR markers across the 18 rice genotypes ranged from 38.9% (RM280 and RM447) to 100% (RM490, RM318, RM279, RM18877 and RM20033, RM19303) with an average of 76.58%. Also, cross-species transferability across chromosome ranged from 54.4% (chromosome 4) to 86.5% (chromosome 2) with an average of 74.35%. The polymorphism information content of the markers varied from 0.198 (RM263) to 0.868 (RM510) with a mean of 0.549 ± 0.153, showing high discriminatory power. The highest rate of cross-transferability was observed in O. rufipogon (97%), The highest rate of cross-species transferability was in O . rufipogon (97.00%), followed by O. glaberrima (94.20%) , O. nivara (92.80%), Swarna (92.80%), O. longistaminata (91.40%), O. eichingeri (90%), O. barthii (88.50%), O. alta (82.80%), O. australiensis (77.10%), O. grandiglumis (74.20%), O. officinalis (74.20%), Zizania latifolia (70.00%), O. latifolia (68.50%), O. brachyantha (62.80%), Leersia perrieri (57.10%) and O. ridleyi (41.40%) with least in O. coarctata (28.50%). A total of 341 alleles from 70 loci were detected with the number of alleles per locus ranged from 2 to 12. Based on dendrogram analysis, the AA genome groups was separated as distinct group from the rest of the genome types. Similarly, principal coordinate analysis and structure analysis clearly separated the AA genome type from the rest of the genome types. Through the analysis of molecular variance, more variance (51%) was observed among the individual, whereas less (14%) was observed among the population. Thus, our findings may offer a valuable resource for studying the genetic diversity and relationship to facilitate the understanding of the complex mechanism of the origin and evolutionary processes of different Oryza species and wild relative rice., Competing Interests: Competing interestsThe authors declare that they have no potential competing interests.