Int.J.Curr.Microbiol.App.Sci (2020) 9(7): 210-227 210 Original Research Article https://doi.org/10.20546/ijcmas.2020.907.024 Genotypic Assessment of Bacterial Leaf Blight Resistance in Indigenous Rice (Oryza sativa L.) Germplasm R. Ashiba 1* , K. Eraivan Arutkani Aiyanathan 1 , R. Kannan 1 and M. Arumugam Pillai 2 1 Department of Plant Pathology, 2 Department of Plant Breeding and Genetics, Agricultural College & Research Institute, Tamilnadu Agricultural University, Killikulam - 628252, Tamilnadu, India *Corresponding author ABSTRACT Introduction The world’s most daring problem is to nourish the developing population which is expected to reach 8 billion individuals by 2020, due to expanding population (Kubo and Purevdorj, 2004). As the population builds, the production of food diminishes due to an absence of reasonable land for crop development. The infection caused due to bacterial pathogens becomes a major challenge for the rice breeders. BLB is a vascular disease that causes a white yellow discoloration in rice crop along veins, leaf margins, leaf blades and those lesions may extend to the sheath (Gnanamanickam et al., 1999). In rice it causes annual yield losses conservatively estimated at 50% (Song and Goodman, 2001). When the rice is infected by Xanthomonas oryzae pv. oryzae, although the International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 9 Number 7 (2020) Journal homepage: http://www.ijcmas.com One hundred rice genotypes were analyzed to evaluate the genetic polymorphism and identification of resistant lines to bacterial leaf blight (BLB) disease caused by Xanthomonas oryzae pv. oryzae using simple sequences repeat (SSR) markers. A total of 38 alleles were detected by seven polymorphic markers showing highly polymorphic across all genotypes with an average of 5.42 alleles per polymorphic marker. The marker RM-21, RM-122 and RM-224 produced maximum 6 alleles. The PIC values ranged from 0.345 to 0.688 and marker RM-21 was found to be the most appropriate marker to discriminate BLB resistant rice genotypes owing to the highest PIC value of 0.688. The cluster analysis showed that these genotypes grouped into four clusters, in which cluster IV had maximum forty genotypes followed by cluster III and cluster I. Multiple resistance ® genes (Xa21+ xa13+xa5+Xa4) were identified in germplasms such as Dhalakeera, Swarnamasuri, Purple puttu, Veethiruppu showing high level of resistance to BLB, while Navarai black 5571and Kalyani were found to be moderately resistant to BLB disease in both field and controlled condition. These genetically diverse BLB resistant genotypes can be directly utilized in rice BLB resistance breeding programs. Keywords Rice germplasm, BLB, Resistance, Genetic diversity, Cluster analysis Accepted: 05 June 2020 Available Online: 10 July 2020 Article Info