SCREENING OF BLAST RESISTANCE GENE IN BORO RICE (Oryza sativa L.) GENOTYPES BASED ON SSR MARKERS

Abstract

The major focus on the study was on the assessing blast resistance genes in boro rice germplasms using gene-specific SSR markers. The study involved 40 boro rice genotypes, including landraces, purple rice and BRRI release varieties. DNA extraction and PCR amplifications were performed using five blast gene-specific SSR primers viz. RM 541, RM 224, RM 527, RM 162 and RM 206 were used to identify the presence or absence of blast resistance genes Pi-9, Piz-5, Pi-2(t), Pi-1, and Pi-kh. The amplicons were differentiated using agarose gel electrophoresis and the genetic frequencies of the blast resistance genes were estimated. The genetic frequencies of five major blast resistance genes [Pi-9, Pi-1, Piz-5,Pi 2(t) and Pi-kh] were ranged from 35% to 85%. The blast resistance gene Pi-2(t) was widely (85%) and Pi5 was sparsely (35%) distributed among the studied genotypes. The study also included a genetic distance-based analysis, which revealed five major clusters of rice genotypes with varying resistance gene profiles. Furthermore, the study delivered into the correlations between disease scores and resistant genes, highlighting the negative correlation between disease scores and the total number of blast disease resistance genes. The Spearman rank correlations of selected boro rice genotypes demonstrated the relationship between the phenotypic expression and the total number of blast resistance genes. Additionally, the study involved principal component analysis (PCA) to visually represent the diversity of the genotypes. The PCA scatter plot successfully separated the rice genotypes into distinct groups based on their resistance profiles, providing a comprehensive visualization of the genetic diversity of the boro rice genotypes. In summary, the study successfully assessed blast resistance genes in boro rice germplasms using gene-specific SSR markers and provided valuable insights into the genetic frequencies, correlations with disease scores, and the genetic diversity of the rice genotypes. Boro, Ghuniboro1, Kaikkaboro, Borodeshi, Jamirboro and Soloiboro, findings contribute to the understanding of blast resistance in boro rice and have implications for breeding and crop improvement programs aimed at enhancing resistance to blast disease in rice cultivation.