The fgr gene responsible for rice fragrance was restricted within 69 kb

From more than 100 volatile flavor components, 2-acetyl-1-pyrroline (2AP) stands out as the key component of aroma in both basmati- and jasmine-style fragrant rice. It has been reported that a single recessive gene (fgr) on chromosome 8 is responsible for the production of 2AP. Our initial mapping efforts with SSR markers confirmed the previous mapping result, and placed the fgr locus between RM8264 and RM3459 with the physical distance of ∼800 kb. The fgr region was then saturated with high-density markers developed by exploiting sequence diversities between indica and japonica rice subspecies. After mapping with segregant populations consisting of totally 2891 individuals, the fgr locus was restricted to an interval of 69 kb flanked by the left marker L02 and the right marker L06. Furthermore, the fgr locus was confirmed by simultaneous investigation of both genotypes and 2AP levels for the key recombinants and their offspring. Sequence analysis of the fgr region revealed three candidate genes encoding respective eukaryotic-type carbonic anhydrase, 3-methylcrotonyl-CoA carboxylase beta chain, and betaine aldehyde dehydrogenase. The result presented here would pave the way for both cloning and marker-assisted selection of the fgr gene.