Quantitative Trait Loci Mapping for Seed Calcium Content of Soybean

Abstract

ABSTRACTCalcium content is one of the determining characteristics of seed texture affecting soyfood quality. Seed with higher calcium content tends to have harder texture, which is not desirable for certain soyfood such as natto. Molecular markers and quantitative trait loci (QTL) for seed calcium will facilitate the development of elite cultivars with desired calcium content through marker assisted selection (MAS). The objectives of this study were to (i) identify new QTL and associated markers and (ii) confirm previously reported QTL for calcium content. A high calcium parent, PI 407818 B, was crossed with two low calcium parents, KS4303sp and PI 408052 C, creating two mapping populations with 120 and 124 progeny each. Mapping populations were screened with simple sequence repeat (SSR) markers and tested for calcium content. The F2:4 and F2:5 lines from the two populations were grown in a randomized complete block design (RCBD) with two replications, at two Arkansas locations in 2 yr. Composite interval mapping (CIM) for SSR markers revealed a novel QTL Ca5 for seed calcium content that is located approximately at 13cM and linked to Sat_290 and Satt115 on chromosome 18 with a logarithm of the odds (LOD) score of 2.7. Single marker analysis revealed 13 markers for seed calcium content that are stable across environments on chromosomes 1, 2, 5, 7, 8, 18, and 20. Previously reported markers linked to QTL Ca1 (chr. 8), Ca3, and Ca4 (chr. 7) were confirmed in both populations, while Ca2 (chr. 20) was confirmed only in the population derived from KS4303sp × PI 407818 B. These confirmed and newly identified QTL with associated markers offer a potential tool for MAS for calcium content.