Marker-assisted improvement of the elite Basmati variety, IET18006 for resistance against bacterial blight and blast

Abstract

IET 18006 is an elite Basmati variety, with highly desirable long slender grain type and medium duration and possesses excellent aroma. However, the variety is highly susceptible two major diseases, viz., bacterial blight (BB) and blast which reduce yield of the elite Basmati variety significantly. We have improved IET 18006 through targeted introgression of the major BB resistance genes, Xa21 and xa13 and the major blast resistance gene, Pi54 through marker-assisted backcross breeding (MABB). The elite variety, Improved Samba Mahsuri (ISM) possessing bacterial blight resistant genes Xa21 and xa13 and a Vietnamese variety, Tetep possessing blast resistant gene, Pi54 were used as donor parents for improvement of IET 18006 through two sets of backcrosses and backcrossing was continued till BC2 generation. At each backcross generation, plants possessing Xa21, xa13 and Pi54 in heterozygous condition were identified with help of gene-specific markers through foreground selection; while a set of parental polymorphic SSR markers were used for background selection. At BC2F2, a promising backcross plant possessing Xa21 + xa13 was intermated with a backcross plant possessing Pi54 to generate intercross F1s (i.e. ICF1s), which were then selfed. At ICF2 generation, plants which possessing Xa21 + xa13 + Pi54 in homozygous condition were identified with the help of gene specific markers and advanced further through selfing. At ICF4¬, four promising three-gene pyramid lines of IET 18006 possessing high level of resistance against both BB and blast along with high yield and grain type similar to the recurrent parent were identified.