Identification of novel SNPs in Pun1 locus for pungency in Capsicum species

Capsaicin and its analogues known as capsaicinoids are the principal sources of pungency in Capsicum spp. In this study, characterization of North-West Himalayan chilli germplasm and commercial landraces of different Indian states known for different pungency-color combinations was done based on capsaicin concentration. Moreover, molecular variation in pungency among high, medium and mild/not pungent Capsicum spp., especially those adapted to North-West Himalayas were elucidated.

Forty-nine genotypes of chilli comprising breeding lines of Kashmiri origin, commercial landraces of Southern Indian origin and one of the world's hottest chilli Bhut Jolokia from Nagaland state of India were used as an experimental material. Wide variation in capsaicin content was observed among the genotypes, wherein, Bhut Jolokia (Capsicum chinense) expressed the highest capsaicin content (10,500.75 µg/g). Further, molecular analysis of PunI gene was done for discovering SNPs responsible for variations in pungency. In the non-pungent Nishat-1 (Capsicum annuum var. grossum), the 650 bp DNA fragment was not amplified due to 2.5 kb deletion spanning the putative promoter and first exon of AT3. The amplified DNA product for high and medium pungent was sequencing. Sequence alignment among revealed SNPs which were further observed responsible for variations in amino acid sequence and protein structure.

The observed variation in protein structure might be responsible for high capsaicin production in one genotype as compared to the other and hence the protein conformation determines its interaction with the substrate.