Author(s): N. CHOUDHURY, J. TARAFDAR AND P. P. SUR

Abstract: Sweet potato has diverse colored phenotypes of storage tuber, yet very little research reflects the biochemical background of this diversity. Our present study was devoted to characterize the regulatory and structural genes in some Indian orange and purple fleshed sweet potato cultivars. cDNA was synthesized from cultivars like 362-7, S-1221, SV -98, S-61, DOP-92-120 and RTPCR was done using gene specific primers of regulatory genes like IT1, IT4 (from purple fleshed variety, DOP-92-120) and structural gene like 3GT (3 –O-glucosyl transferase). The amplified fragments of the respective genes were cloned and sequenced. IT1 showed no significant homology whereas IT4 (HE980452) showed homology with mRNA for sporamin A precursor molecule. The IT666 (HE980451) gene of MYB gene family showed high similarity with R2R3 type regulatory factor for anthocyanin biosynthesis. The structural gene (HE978836) showed 95% homology with Ipomoea trifida isolate UDP flavonoid: 3-glucosyl transferase (UFGT) gene, partial sequence (EU852747). The comparative analysis of sequences of IT4 (HE980452) and IT666 (HE980451) with published gene sequences of IbMYB2 gene family confirmed the function of these genes for biosynthesis of anthocyanin pigments in the storage root of sweet potato. Furthermore, IT666 was cloned and sequenced. Our result indicated that IbMYB1 alone was sufficient for induction of structural genes and anthocyanin accumulation in tuberous roots.

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