Dataset Information

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

ABSTRACT:

Background

Soybean (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.

Results

In 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.

Conclusions

To 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.

SUBMITTER: Gutierrez-Gonzalez JJ

PROVIDER: S-EPMC3224685 | biostudies-literature | 2010 Jun

REPOSITORIES: biostudies-literature

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Publications

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

Gutierrez-Gonzalez Juan J JJ Wu Xiaolei X Gillman Jason D JD Lee Jeong-Dong JD Zhong Rui R Yu Oliver O Shannon Grover G Ellersieck Mark M Nguyen Henry T HT Sleper David A DA

BMC plant biology 20100611

<h4>Background</h4>Soybean (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 invol ...[more]

PMID: 20540761

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Project description:Soybean (Glycine max (L.) Merr.) isoflavone is important for human health and plant defense system. To identify novel quantitative trait loci (QTL) and epistatic QTL underlying isoflavone content in soybean, F5:6, F5:7 and F5:8 populations of 130 recombinant inbred (RI) lines, derived from the cross of soybean cultivar 'Zhong Dou 27' (high isoflavone) and 'Jiu Nong 20' (low isoflavone), were analyzed with 95 new SSR markers. A new linkage map including 194 SSR markers and covering 2,312 cM with mean distance of about 12 cM between markers was constructed. Thirty four QTL for both individual and total seed isoflavone contents of soybean were identified. Six, seven, ten and eleven QTL were associated with daidzein (DZ), glycitein (GC), genistein (GT) and total isoflavone (TI), respectively. Of them 23 QTL were newly identified. The qTIF_1 between Satt423 and Satt569 shared the same marker Satt569 with qDZF_2, qGTF_1 and qTIF_2. The qGTD2_1 between Satt186 and Satt226 was detected in four environments and explained 3.41%-10.98% of the phenotypic variation. The qGTA2_1, overlapped with qGCA2_1 and detected in four environments, was close to the previously identified major QTL for GT, which were responsible for large a effects. QTL (qDZF_2, qGTF_1 and qTIF_2) between Satt144-Satt569 were either clustered or pleiotropic. The qGCM_1, qGTM_1 and qTIM_1 between Satt540-Sat_244 explained 2.02%-9.12% of the phenotypic variation over six environments. Moreover, the qGCE_1 overlapped with qGTE_1 and qTIE_1, the qTIH_2 overlapped with qGTH_1, qGCI_1 overlapped with qDZI_1, qTIL_1 overlapped with qGTL_1, and qTIO_1 overlapped with qGTO_1. In this study, some of unstable QTL were detected in different environments, which were due to weak expression of QTL, QTL by environment interaction in the opposite direction to a effects, and/or epistasis. The markers identified in multi-environments in this study could be applied in the selection of soybean cultivars for higher isoflavone content and in the map-based gene cloning.

Project description:BACKGROUND: Improvement of ?-tocopherol content is an important breeding aim to increase the nutritional value of crops. Several efforts have been conducted to improve the ?-tocopherol content in soybean [Glycine max (L.) Merr.] through transgenic technology by overexpressing genes related to ?-tocopherol biosynthesis or through changes to crop management practices. Varieties with high ?-tocopherol content have been identified in soybean germplasms. The heritability of this trait has been characterized in a cross between high ?-tocopherol variety Keszthelyi Aproszemu Sarga (KAS) and low ?-tocopherol variety Ichihime. In this study, the genetic mechanism of the high ?-tocopherol content trait of KAS was elucidated. RESULTS: Through QTL analysis and fine mapping in populations from a cross between KAS and a Japanese variety Ichihime, we identified ?-TMT3, which encodes ?-tocopherol methyltransferase, as a candidate gene responsible for high ?-tocopherol concentration in KAS. Several nucleotide polymorphisms including two nonsynonymous mutations were found in the coding region of ?-TMT3 between Ichihime and KAS, but none of which was responsible for the difference in ?-tocopherol concentration. Therefore, we focused on transcriptional regulation of ?-TMT3 in developing seeds and leaves. An F5 line that was heterozygous for the region containing ?-TMT3 was self-pollinated. From among the progeny, plants that were homozygous at the ?-TMT3 locus were chosen for further evaluation. The expression level of ?-TMT3 was higher both in developing seeds and leaves of plants homozygous for the ?-TMT3 allele from KAS. The higher expression level was closely correlated with high ?-tocopherol content in developing seeds. We generated transgenic Arabidopsis plants harboring GUS gene under the control of ?-TMT3 promoter from KAS or Ichihime. The GUS activity assay showed that the activity of ?-TMT3 promoter from KAS was higher than that of Ichihime. CONCLUSIONS: The genetic variation in ?-TMT3, which plays a major role in determining ?-tocopherol concentration, provides significant information about the regulation of tocopherol biosynthesis in soybean seeds. This knowledge will help breeding programs to develop new soybean varieties with high ?-tocopherol content.

Dataset Information

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

Background

Results

Conclusions

Publications

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

Similar Datasets

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