Marker–assisted pyramiding of bacterial blight and gall midge resistance genes in Samba Mahsuri and study of their interactions

Divya D; Bhaskar Naik S; Sundaram R.M; Laha G.S; Bentur J.S

Volume : IV, Issue : VI, June - 2015

Marker–assisted pyramiding of bacterial blight and gall midge resistance genes in Samba Mahsuri and study of their interactions

Divya D, Bhaskar Naik S, Sundaram R. M, Laha G. S, Bentur J. S

Abstract :

Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae and gall midge (Orseolia oryzae) are two major constraints in rice production. In order to combine BB and GM resistance genes against two constraints, B277– SM2113 (a NIL of Samba Mahsuri) possessing BB resistance genes xa13 and Xa21 was individually crossed with two GM resistant varieties viz., Kavya possessing Gm1 (conferring HR– type resistance) and Abhaya possessing Gm4 (conferring HR+ type resistance). True F1 s from the individual crosses were again crossed to combine all 4 resistance genes. The resulting IF1 s possessing all the 4 resistance genes in heterozygous condition were selfed to generate IF2 plants. A total of 35 IF2 plants were obtained. All the 35 IF2 plants were vegetatively multiplied through tiller separation technique, genotyped with gene specific markers for all 4 resistance genes and phenotypically evaluated against both BB and gall midge. Out of 35 IF2 plants tested, a single plant showed the presence of two BB and two gall midge resistance genes in homozygous condition. Four plants carrying only BB resistance genes exhibited gall midge resistance in addition to BB resistance, while nine plants carrying only gall midge resistance genes exhibited BB resistance in addition to gall midge resistance indicating pleiotropic effect of the BB/GM resistance genes. Majority of the plants (82%) possessing both gall midge resistance genes i.e., Gm1 and Gm4 showed HR+ type resistance indicating preponderance of HR+ reaction over HR– type reaction.