# QTL/Segment Mapping and Candidate Gene Analysis for Oil Content Using a Wild Soybean Chromosome Segment Substitution Line Population

## TL;DR

This study identifies genetic regions and candidate genes affecting oil content in soybeans using wild and cultivated soybean lines.

## Contribution

The study discovers a novel candidate gene for oil content and validates a known gene using a chromosome substitution population.

## Key findings

- Two major QTL/segments (qOC14 and qOC20) explain 39.46% of oil content variation in soybeans.
- A novel candidate gene, Glyma.14G179800, and a known gene, Glyma.20G085100 (POWR1), are linked to oil content regulation.
- Wild alleles at these QTLs reduce oil content, consistent with wild soybeans having lower oil.

## Abstract

Annual wild soybean, the ancestor of cultivated soybean, underwent a significant increase in seed oil content during domestication. To elucidate the genetic basis of this change, a chromosome segment substitution line population (177 lines) constructed with cultivated soybean NN1138-2 as recipient and wild soybean N24852 as donor was used in this study. Phenotypic evaluation across three distinct environments led to the identification of two major QTL/segments, qOC14 on chromosome 14 and qOC20 on chromosome 20, which collectively explained 39.46% of the phenotypic variation, with individual contributions of 17.87% and 21.59%, respectively. Both wild alleles exhibited negative additive effects, with values of −0.35% and −0.42%, respectively, consistent with the inherently low oil content of wild soybeans. Leveraging transcriptome and genome data from the two parents, two candidate genes were predicted. Notably, Glyma.14G179800 is a novel candidate gene encoding a PHD-type zinc finger domain-containing protein, and the hap-A haplotype exhibits a positive effect on oil content. In contrast, Glyma.20G085100 is a reported POWR1 gene, known to regulate protein and oil content. Our findings not only validate the role of known gene but, more importantly, unveil a new candidate gene, offering valuable genetic resources and theoretical targets for molecular breeding of high-oil soybean.