Intricate environment-modulated genetic networks control isoflavone accumulation in soybean seeds

Abstract

BackgroundSoybean (Glycine max [L] Merr.) seed isoflavones have long been considered a desirable trait to target in selection programs for their contribution to human health and plant defense systems. However, attempts to modify seed isoflavone contents have not always produced the expected results because their genetic basis is polygenic and complex. Undoubtedly, the extreme variability that seed isoflavones display over environments has obscured our understanding of the genetics involved.ResultsIn this study, a mapping population of RILs with three replicates was analyzed in four different environments (two locations over two years). We found a total of thirty-five main-effect genomic regions and many epistatic interactions controlling genistein, daidzein, glycitein and total isoflavone accumulation in seeds. The use of distinct environments permitted detection of a great number of environment-modulated and minor-effect QTL. Our findings suggest that isoflavone seed concentration is controlled by a complex network of multiple minor-effect loci interconnected by a dense epistatic map of interactions. The magnitude and significance of the effects of many of the nodes and connections in the network varied depending on the environmental conditions. In an attempt to unravel the genetic architecture underlying the traits studied, we searched on a genome-wide scale for genomic regions homologous to the most important identified isoflavone biosynthetic genes. We identified putative candidate genes for several of the main-effect and epistatic QTL and for QTL reported by other groups.ConclusionsTo better understand the underlying genetics of isoflavone accumulation, we performed a large scale analysis to identify genomic regions associated with isoflavone concentrations. We not only identified a number of such regions, but also found that they can interact with one another and with the environment to form a complex adaptable network controlling seed isoflavone levels. We also found putative candidate genes in several regions and overall we advanced the knowledge of the genetics underlying isoflavone synthesis.

Isoflavone concentration of soybean meal from various origins and transfer of isoflavones into milk of dairy cows

“…are the richest source of isoflavones (Cederroth and Nef 2009;Hollman 2001) ranging from 1.2 to 4.2 mg/kg dry matter (DM; Kurzer and Xu 1997). Isoflavone concentrations were found to vary within cultivars (Eldridge and Kwolek 1983;Hoeck et al 2000;Wang et al 2000), and their contents were fluctuating even though identical varieties were grown at different locations (Carrao-Panizzi et al 1999;Charron et al 2005;Yin and Vyn 2005) under differing climatic (Tsukamoto et al 1995) and plant stress conditions (Caldwell et al 2005;Gutierrez-Gonzalez et al 2009, 2010.…”

Additional Quantitative Trait Loci and Candidate Genes for Seed Isoflavone Content in Soybean

“…Another high density genetic linkage maps was constructed using the 1,536 Universal Soy Linkage Panel 1.0 SNP markers in the 'PI 438489B' by 'Hamilton' populations and 31 linkage groups were obtained and used in this study . Up to date several isoflavones QTL were identified from the linkage map constructed by different markers (Kassem et al, 2004;Gutierrez-Gonzalez et al, 2009;Zeng et al, 2009;Gutierrez-Gonzalez et al, 2010). SNP markers allow the anchoring of genetic maps and QTL on the soybean genome sequence so identifying large genomic regions each containing several hundred genes.…”

Differential regulation of defense-related proteins in soybean during compatible and incompatible interactions between Phytophthora sojae and soybean by comparative proteomic analysis

“…Plant defense metabolites arise from the main secondary metabolic routes; i.e., the phenylpropanoid, isoprenoid, and alkaloid pathways (Gutierrez-Gonzalez et al 2010). In this study, 15 proteins (spots 47-60) were identified as being involved in the phenylpropanoid pathway (Fig.…”