Dept. of Genetics & Plant Breeding, University of Agricultural Sciences, Bangalore 560 065.
* Corresponding author: heshashidhar@rediffmail.com
1Present address: Dept. of. Agronomy, Faculty of Agriculture, University of Damascus, Damascus, Syria.
Identification of molecular markers associated with genes controlling drought resistance in rice is a necessary step to Improve breeding efficiency for this complex trait. Two backcross populations comprising 180 BC1F3 individuals derived from crosses involving two doubled-haploid (DH) lines with IR64 as recurrent parent were evaluated for root morphology under low-moisture stress along with their parents and standard checks. The DH line P124 (a shallow-rooted line) and P331 (deep-rooted one) are constituents of the mapping population derived from a cross between IR64 and Azucena. The BC1F3 plants were selectively genotyped using microsatellite (SSA) and AAPD primers with different strategies. In P331 x IR64 population, fifteen SSA primers pairs were screened across 80 plants. Single-marker analysis revealed 10 QTL linked to microsateliite markers. A quantitative trait locus for maximum root length (MAL) was found co-segregating with AM317 explaining 43.4% of total phenotypic variation. In PI24 x IR64 population, individual segregant analysis was used to identify AAPD markers associated with root traits of twenty extreme individual selected based on MAL. Six putative markers showed highly significant association with MAL, root number, root dry weight and root volume. Only one marker namely OPAH13 showed significant co-segregation with QTL for MAL at 5% and explained 6.2% of the phenotypic variation across 80 Individuals. Thus, these markers (AM317 and OPAH13) could be used for marker-assisted plant breeding programs to develop drought resistant varieties.
Rice, backcross popUlation, drought, maximum root length, molecular marker
