Fragrance analysis using molecular and biochemical methods in recombinant inbred lines of rice
The aroma or fragrance of Basmati rice is associated with the presence and content of the chemical compound, 2-acetyl-1-pyrroline and the trait is monogenic recessive. Several polymerase chain reaction (PCR)-based co-dominant markers based on RG28 locus were developed, which can differentiate between fragrant and non-fragrant rice cultivars. For molecular and biochemical analysis of aroma, a mapping population comprising 208 recombinant inbred lines (RILs) derived from a diverse cross between CSR10 and Taraori Basmati through Single seed descent (SSD) method was used. RILs are among the best mapping populations, which provide a novel material for linkage mapping of genes/QTLs marker for various traits. Biochemical analysis of aroma was performed with the 1.7% KOH solution and molecular analysis of aroma was carried out with microsatellite markers present on chromosome 8 (BAD2, BADEX7-5, SCUSSR1) to determine the extent of association between trait, marker and chromosome 8. Among these markers, BAD2 amplified aroma specific alleles having 256 bp in 72 lines, BADEX7-5 with 95 bp in 74 lines and SCUSSR1 with 129 bp in 79 lines. Mantel test of significance detected by biochemical analysis of RILs (with 1.7% KOH) and molecular marker study revealed high degree (>90%) of association of aroma with the above mentioned markers, respectively. Some of the F10 lines amplified the heterozygous alleles for two sets of specific markers (BAD2 and SCUSSR-1) but did not show the presence of aroma as analyzed by chemical test. Aromatic and non-aromatic lines were almost common in three markers, indicating association of markers with the trait and chromosome 8. The results reveal that these markers could be used for marker assisted selection and RIL population for mapping of aroma QTLs/genes.
Key words: Basmati, recombinant inbred lines, fragrance, association.