Patterns of nucleotide diversity on the waxy locus linked to AAC of rice (Oryzae sativa L.) in northeast India

Title : Patterns of nucleotide diversity on the waxy locus linked to AAC of rice (Oryzae sativa L.) in northeast India

Abstract:

Northeast India represents one the world’s biodiversity hotspots which harbours an enormous gene pool. Starch quality mainly controlled by the Waxy locus codes for GBSSI providing a unique model for elucidation of regulation at the molecular level. Sequence analysis of this region is expected to give novel insights into the structure, function and evolution of the different set of alleles encoding different levels of granule-bound starch synthases in rice varieties. A comprehensive comparative analysis of the genomic sequences targeting the 7.5 kb Wx locus on 35 rice accessions identified wx, Wx^op, Wx^b, Wxⁱⁿ alleles unique to waxy (0-5%), very low(6-10%), low (11-20%) and intermediate(21-25%) respectively. Further, investigations on the nucleotide sequences of rice germplasm have revealed the presence of two alleles (Wx^a1 and Wx^a2) that control accumulation of amylose content in rice endosperm. Wx^a1 allele was found to be present in rice cultivars with apparent amylose content (AAC) ranging from 25-27% (High I) and Wx^a2 allele was uniquely present in rice cultivars with AAC ranging from 27-33% (High II). A molecular phylogenetic tree constructed using the Wx gene sequence gave rise to six distinct clades corresponding to the allele wx, Wx^op, Wx^b, Wxⁱⁿ Wx^a1 and Wx^a2. The Wx^b, Wxⁱⁿ and wx allele  joined the japonica lineage whereas allele Wx^op, Wx_a¹and Wx_a² were linked to indica lineage. These results strongly suggest that allelic diversification occurred after divergence of the two main varietal groups (indica and japonica) and molecular evidence supporting the single evolutionary origin of domesticated rice.

Biography:

Gayle Alisha Kharshiing, a native to the north-eastern region of India is a region that is recognised as one of the biodiversity hotspot regions of the world. The potential of uncovering enormous amount information this region holds drove her into a career in research. She successfully completed her graduation and a master’s degree program the field of Biotechnology during which she was trained in techniques such as High throughout sequencing, NGS, Real-time PCR etc. and acquired two publications. She is currently in her final year of Ph.D under the guidance of Prof. Nikhil K. Chrungoo, under the Dept. of Botany