Molecular and biochemical markers associated with leaffolder (Cnaphalocrocis medinalis G.) resistance in rice (Oryza sativa L.).

Association of molecular markers namely isozymes and simple sequence repeats (SSRs) and various biochemical markers to leaffolder (Cnaphalocrocis medinalis G., a predominant insect pest of rice) resistance were studied in rice (Oryza sativa L.). Recombinant inbred lines (RILs) of F8 generation obtained by crossing IR36 (susceptible parent) and TNAULFR831311 (moderately resistant parent) were used in this study. Soluble protein content, protein profile, and peroxidase and phenylalanine ammonia lyase (PAL) activities were the various biochemical markers studied. Decrease in soluble leaf protein content was observed in all lines, due to insect infestation. Protein profiling revealed an enhanced expression of a high molecular mass (> 97 kDa) protein in all the infested lines. Besides, there was an increased induction of a 38 kDa protein in infested resistant parent and resistant RILs. A significant increase in peroxidase and PAL activities was observed after infestation. In peroxidase isozyme analysis, carried out after infestation, "isoform 1" was found to be more prominent in the susceptible lines and "isoform 2" in the resistant lines. Bulk segregant analysis (BSA) with twenty-five rice microsatellites (RM) resulted in identification of three polymorphic markers between bulks RM11 and RM432 located on chromosome 7 and RM271 on chromosome 10 of rice. These markers may be associated with leaffolder resistance in rice and can be used in marker-assisted selection for leaffolder resistance in rice.