Identification of Genomic Regions for Fodder Quality Traits in Sorghum Recombinant Inbred Lines _RIL_ Population Under Different Water Regimes

Abstract

Digestibility and lignin content are very important in determining feed quality and plant fitness, with higher lignin content reducing digestibility and vice versa. A 5% variation in fodder digestibility between poor and premium fodder is reported to result in a 20% price variation. Sorghum is gaining importance as a food, feed, and fuel crop. Therefore, two sorghum populations, a recombinant inbred line (RIL) population (n=320) and reference set (n=130) were evaluated under drought for fodder qualities. In this study, irrigation was withheld at the booting stage for the stress plots whereas the control plots were fully irrigated, all other crop management practices were performed equally. The dry weight (DW) was recorded at maturity, and the fodder was subjected to near infrared spectroscopy (NIRS) scanning to record nitrogen content on a dry matter basis (NDM); neutral and acid detergent fibre (NDF and ADF); acid detergent lignin (ADL); metabolizable energy (ME) and; in vitro organic matter digestibility (IVOMD). Significant genotypic variation and genotype by treatment variation were recorded for the reference set in 2016 only. Pearson s correlation was pooled across years and treatments for both populations and DW and IVOMD showed negative correlations with NDF and ADL, while positive correlations were observed between DW, ME and IVOMD in the RIL population. However, in the reference set there was no strong positive or negative correlation between DW, ME and IVOMD. Genotyping by sequencing (GBS) analysis was used to perform quantitative trait loci (QTL) estimation for the RIL population while a genome wide association study (GWAS) was performed for the reference set. A total of 98 and 47 associated genes were extracted from Phytozome v12.1.6 for the RIL and reference populations respectively. Several genes belong to pathways that may help explain a causal functionality with the associated traits.