Characterization of Indian waxy and non-waxy maize germplasm for genetic differentiation through SNP genotyping.

Abstract

Waxy maize characterized by high amylopectin content resulting from a recessive wx1 gene, is important for both dietary and industrial applications, yet it suffers from low yields and limited breeding options. This study aims to develop a thorough understanding of the underlying genetics for successful hybridization experiments in waxy maize and the identification of potential cross combinations to derive high-yielding waxy maize hybrids in India. Here, we evaluated the kernel starch composition, yield-related traits, molecular diversity, kinship, LD, population structure, and selection signatures in a panel of 11 waxy and 37 non-waxy maize genotypes. The starch content in the panel ranged from 57.85 to 66.96%, while the amylopectin ranged from 70.65% to 96.32%. A significant positive correlation between kernel starch and amylopectin (0.39**) was identified suggesting the potential for simultaneous improvement of both these traits. The 48 maize lines were genotyped with 24,477 highly polymorphic single nucleotide polymorphisms (SNPs). Seventy-eight per cent of the pair-wise relative kinship values were less than or equal to 0, indicating minimal redundancy in the genomic composition of the inbred lines. The range of genetic distance among the pairs of waxy lines was 0.190 to 0.231 as compared to 0.076-0.264 in the non-waxy genotypes suggesting a greater genetic variation among the non-waxy genotypes. The mean LD value across the genome was 0.44. Two to four groups were identified using the model-based population structure, phylogenetic analysis and principal component analysis with no clear pattern of clustering based on the type of corn. Pairwise comparisons using the SNP dataset between waxy and non-waxy maize detected 27 loci under positive selection. The information generated in this study will be useful in the diversification of Indian waxy maize lines and the development of superior waxy maize hybrids.