ABSTRACT
Soybean isoflavones play diverse roles in human health, including cancers, osteoporosis, heart disease, menopausal symptoms and pabulums. The objective of this study was to identify the quantitative trait loci (QTL) associated with the isoflavones daidzein (DC), genistein (GeC), glycitein (GlC) and total isoflavone contents (TIC) in soybean seeds. A population of 184 F2:10 recombinant inbred lines derived from a 'Xiaoheidou' x 'GR8836' cross was planted in pot and field conditions to evaluate soybean isoflavones. Twenty-one QTL were detected by composite interval mapping. Several QTL were associated with the traits for DC, GeC, GlC and TIC only. QDGeGlTIC4_1 and QDGlTIC12_1 are reported first in this study and were associated with the DC, GeC, GlC and TIC traits simultaneously. The QTL identified have potential value for marker-assisted selection to develop soybean varieties with desirable isoflavone content.
Subject(s)
Genes, Plant , Glycine max/genetics , Isoflavones/biosynthesis , Seeds/genetics , Chromosome Mapping , Genetic Association Studies , Genetic Linkage , Genetic Markers , Genetic Variation , Hybridization, Genetic , Isoflavones/genetics , Phenotype , Quantitative Trait Loci , Seeds/metabolism , Glycine max/metabolismABSTRACT
MYB transcription factors play important roles in the regulation of plant growth, developmental metabolism and stress responses. In this study, a new MYB transcription factor gene, GmMYBJ1, was isolated from soybean [Glycine max (L.)]. The GmMYBJ1 cDNA is 1296bp in length with an open reading frame (ORF) of 816 bp encoding for 271 amino acids. The amino acid sequence displays similarities to the typical R2R3 MYB proteins reported in other plants. Transient expression analysis using the GmMYBJ1-GFP fusion gene in onion epidermal cells revealed that the GmMYBJ1 protein is targeted to the nucleus. Quantitative RT-PCR analysis demonstrated that GmMYBJ1 expression was induced by abiotic stresses, such as drought, cold, salt and exogenous abscisic acid (ABA). Compared to wild-type (WT) plants, transgenic Arabidopsis overexpressing GmMYBJ1 exhibited an enhanced tolerance to drought and cold stresses. These results indicate that GmMYBJ1 has the potential to be utilized in transgenic breeding lines to improve abiotic stress tolerance.
Subject(s)
Arabidopsis/metabolism , Cold Temperature , Dehydration , Glycine max/metabolism , Plant Proteins/metabolism , Stress, Physiological , Transcription Factors/metabolism , Active Transport, Cell Nucleus , Amino Acid Sequence , Arabidopsis/genetics , Arabidopsis/physiology , Cell Nucleus/metabolism , Molecular Sequence Data , Plant Proteins/chemistry , Plant Proteins/genetics , Glycine max/genetics , Glycine max/physiology , Transcription Factors/chemistry , Transcription Factors/genetics , TransgenesABSTRACT
Isoflavones play diverse roles in plant-microbe interactions and are potentially important for human nutrition and health. To study the regulation of isoflavonoid synthesis in soybean, the R2R3-MYB transcription factor GmMYB12B2 was isolated and characterized. Yeast expression experiments demonstrated that GmMYB12B2 showed transcriptional activity. GmMYB12B2 was localized in the nucleus when it was transiently expressed in onion epidermal cells. Real-time quantitative PCR analysis revealed that GmMYB12B2 transcription was increased in roots and mature seeds compared with other organs. The gene expression level in immature embryos was consistent with the accumulation of isoflavones. CHS8 is a key enzyme in plant flavonoid biosynthesis. Transient expression experiments in soybean calli demonstrated that CHS8 was regulated by GmMYB12B2 and produced more fluorescence. The expression levels of some key enzymes in flavonoid biosynthesis were examined in transgenic Arabidopsis lines. The results showed that the expression levels of PAL1, CHS and FLS in transgenic plants were significantly higher than those in wild type plants. However, the expression level of DFR was lower, and the expression levels of CHI, F3H and F3'H were the same in all lines. GmMYB12B2 expression caused a constitutive increase in the accumulation of flavonoids in transgenic Arabidopsis lines compared with wild type plants.
