Novel QTL and Meta-QTL Mapping for Major Quality Traits in Soybean.

Changkai Liu,Qiuying Zhang,Yansheng Li,Feifei Wang,Heng Chen,Xue Wang,Xiangwen Pan

doi:10.3389/fpls.2021.774270

Abstract

Isoflavone, protein, and oil are the most important quality traits in soybean. Since these phenotypes are typically quantitative traits, quantitative trait locus (QTL) mapping has been an efficient way to clarify their complex and unclear genetic background. However, the low-density genetic map and the absence of QTL integration limited the accurate and efficient QTL mapping in previous researches. This paper adopted a recombinant inbred lines (RIL) population derived from ‘Zhongdou27’and ‘Hefeng25’ and a high-density linkage map based on whole-genome resequencing to map novel QTL and used meta-analysis methods to integrate the stable and consentaneous QTL. The candidate genes were obtained from gene functional annotation and expression analysis based on the public database. A total of 41 QTL with a high logarithm of odd (LOD) scores were identified through composite interval mapping (CIM), including 38 novel QTL and 2 Stable QTL. A total of 660 candidate genes were predicted according to the results of the gene annotation and public transcriptome data. A total of 212 meta-QTL containing 122 stable and consentaneous QTL were mapped based on 1,034 QTL collected from previous studies. For the first time, 70 meta-QTL associated with isoflavones were mapped in this study. Meanwhile, 69 and 73 meta-QTL, respectively, related to oil and protein were obtained as well. The results promote the understanding of the biosynthesis and regulation of isoflavones, protein, and oil at molecular levels, and facilitate the construction of molecular modular for great quality traits in soybean.

Highlights

The aims of this research were: (1) to detect more stable quantitative trait locus (QTL) associated with isoflavone contents, protein, and oil based on a high-density genetic map; (2) to integrate the QTL obtained from the previous researches according to meta-analysis method; (3) to predict candidate genes which may influence the accumulation of these quality traits using gene functional annotation
This study showed that the meta-analysis method can map stable QTL, which can offset the limitation of traditional approaches of QTL mapping: most of QTL were environmental-dependent loci which might not be effective in the environmental conditions and difficult to utilize in breeding
Isoflavone, soy protein, and soybean oil are momentous quality traits in soybean breeding, for they play a crucial role in human health

Summary

Introduction

Merr.), a leguminous plant that originated from China, is one of the most important crops globally, for it is rich in isoflavones, protein, and oil (Figure 1). A kind of plant secondary metabolite, belongs to a group of 3-phenyl derivatives synthesized by cinnamyl-CoA. Soy isoflavone is generally classified into four main categories: aglycones (AGL), glycosides, acetylglycosides, and malonylglycosides (Sun et al, 2011; Ku et al, 2020). Each category can be further divided into three kinds as well. The AGL include daidzein (DAE), glycitein (GLE), and genistein (GEE). The glucosides (GLU) include daidzin (DA), glycitin (GL), and genistin (GE). The acetylglucosides include acetyldaidzin, acetylglycitin, and acetylgenistin, while the malonylglucosides include malonyldaidzin, malonylglycitin, and QTL for Major Quality Traits

Objectives

Methods

Results

Discussion

Conclusion