Inheritance and Segregation Pattern of Genes Xa21, xa5 and xa13 Causing Bacterial Leaf Blight (BLB) Resistance in Rice (Oryza sativa L.)

The present study aims to investigate the genetic inheritance of resistance to bacterial leaf blight (BLB) in rice by analyzing the segregation of major resistance genes viz. xa5, xa13, and Xa21 in two specific crosses. BLB, caused by Xanthomonasoryzae pv. oryzae (Xoo), is a significant threat to rice cultivation worldwide. To manage this, resistant cultivars can be developed through pyramiding multiple resistance genes. This experiment involved 1392 BC2F2 plants derived from crosses R1853-105-1-82-1×Improved Samba Mahsuri and BPT 2411×Improved Samba Mahsuri. Marker Assisted Selection for three BLB genes (xa5, xa13, and Xa21) was performed at earlier generations and segregation analysis was performed on true breeding plants. Field screening was conducted using clip inoculation method at maximum tillering stage. The result revealed that the population of cross R1853-105-1-82-1×Improved Samba Mahsuri was showed a 7:9 segregation ratio (Resistant: Susceptible) and resistant was governed by two recessive genes (xa5 and xa13) while the population of cross BPT 2411×Improved Samba Mahsuri was found 55:9 (Resistant: Susceptible) segregation ratio and the resistant was governed by one dominant gene (Xa21) and two recessive genes (xa5 and xa13). It verified the existence of all three resistance genes in the population. The produced lines will be used as breeding materials for the development of BLB-resistant cultivars.