MOLECULAR MARKERS FOR MAPPING AND TAGGING GM8 GENE

摘要

A method for tagging and mapping Gm8, a gene conferring resistance to the rice gall midge (Orseolia oryzae), a major insect pest of rice, using AFLPs and RAPDs, onto chromosome 8 of rice is disclosed. Using AFLPs, two fragments, AR257 and AS168, were identified that were linked to the resistant and susceptible phenotypes, respectively. Another resistant phenotype-specific marker, AP 19587, was also identified using RAPDs. SCAR primers based on the sequence of the fragments AR257 and AS 168 failed to reveal polymorphism between the resistant and the susceptible parents. However, PCR using primers based on the regions flanking AR257 revealed polymorphism that was phenotype-specific. In contrast, PCR carried out using primers flanking the susceptible phenotype-associated fragment AS 168, produced a monomorphic fragment. Restriction digestion of these monomorphic fragments revealed polymorphism between the susceptible and resistant parents. Nucleotide BLAST searches revealed that the three fragments show strong homology to rice PAC and BAC clones that formed a contig representing the short arm of chromosome 8. PCR amplification using the above primers on a larger population, derived from a cross between two indica rice varieties, Jhitpiti (resistant parent) and TN1 (susceptible parent), showed that there is a tight linkage between the markers and the Gm8 locus.