Identification and Molecular Characterization of Bacterial Leaf Blight (Xanthomonas Oryzae) Resistance Genes (Xa4, Xa5, Xa13 & Xa21) in Indica Rice (Oryza Sativa L.)

Abstract

Ninety two rice genotypes were subjected to DNA finger printing and were evaluated for resistance to bacterial leaf blight disease under artificia11y induced epiphytotic conditions. The disease scoring was less than 5.6 em in case of BLB resistant genotypes and 1nore than 5.6 cn1 in case of BLB susceptible genotypes. Out of ninety t~·o, seventy one rice genotypes were resistant for bacterial leaf blight disease. The rest nine '"·ere susceptible under artificial • conditions. Four gene specific prin1ers were used to identify bacterial leaf blight resistant genes in rice genotypes. 1\ll four gene specific 1narkers used in this study were linked to bactetial leaf blight resistance genes. Gene specific markers linked to BLB resistant \\as appeared as .)(a4 1sobp ( STS marker RM224) in 66 rice genotypes .. xa51300bp (STS marker RG556) in 8 rice genotypes~ xa/31ooobp (SNP marker RG136) in 73 rice genotypes and Xa2l, c,oobp (STS marker pT i\248) in 32 rice genotypes. The seYenty one resistant gcnor: pe~ had varying nu1nber of B LB resistant genes. All four BLB resistance genes \vere detected in BCtF9 P16, BC2F- P6 and BC':F, P8. In so1ne \,;ases role of enYironmental factors for expression of genes \Vas also noticed. It i~ ju ~tit1ed by the ob<.;Cr\ at ion that se' en teen rice genotypes having varying nun1her of BLB rcsi~tance genes but unahl~ to c\pres~ rest~tnncc in the field conditions. The lines BC.1F9 <-~ BC2F- in\'ohcd in thi" study h;H.I xa/3 in all the 3X lines (BC1 F9 & BC2F7), vvhile .~\'a~ 1 \-\·as obser\'ed in thirt; one out ot 38 1inc~. The line~ BC1F9 & BC2F7 were found to be BLB resi~tant at rnolecular le\ el L~ artificial induced condition. The PR 106 P2 (donor parent of BC1 F9 & BC2F1) is included in this study has 4 ¥a4. xa 13 & )(a21 BLB resistant genes. Application of back cross tnethod \\·as found successtl.1l to develop BLB resistant rice varieties using PR 106 P2 as donor parent.