Kavitha G., Reddi Sekhar M., Senguttuvel P., Mohan Reddy D., Reddy V.L.N., Kalyani M.B. and Sudhakar P.
Abstract
Drought stress is now a major abiotic factor influencing rice yield under the changing climatic conditions. IR58025B is one of the maintainer lines of the well-known WA CMS line (IR58025A) used in commercial rice hybrid production in India. The majority of rice hybrids are released for various ecosystem conditions using the three-line system. As a result, these derived rice hybrids suffer from drastic drop in yield under the conditions of moisture stress. To facilitate the efficient use of complex polygenic traits in hybrid rice molecular breeding research, we developed drought tolerant introgression lines in background of IR58025B by introgression of major QTL controlling grain yield under moisture stress into IR58025B by marker assisted backcrossing. To begin marker assisted back cross breeding for introgression of a desirable trait into a variety from the donor genotype, study of parental polymorphism is a pre-requisite. Unless the parents are polymorphic for the traits of interest, the further selection of plants carrying the traits of interest is not possible in the progenies. We screened all reported SSR primers linked to drought tolerance and observed RM 324 linked to qDTY2.1 and RM 520 linked to qDTY3.1 was polymorphic between Apo and IR58025B. Simultaneously we screened 300 full-genotype SSR markers covering entire genome and observed 88 SSR primers as polymorphic between IR58025B and Apo. After polymorphic survey, we evaluated Apo and IR5025B under moisture stress and control conditions and recorded significant differences among the parents. Apo performed well when compared to IR58025B for all the characters studied under stress conditions. Construction of a Linkage Map could be ensued procuring the generated genotyping data which could further avail QTL analysis and identification of markers linked to drought tolerance.