Department of Plant Science, McGill University , Macdonald Campus, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada.
J Agric Food Chem. 2012 Dec 26;60(51):12421-7. doi: 10.1021/jf3036319. Epub 2012 Dec 12.
Isoflavones have been reported to have putative health-beneficial properties, which has led to increased interest and demand for soybeans and soy-based products. This study was conducted to determine the effects of high-temperature stress on isoflavone concentration and expression of four key genes involved in isoflavone synthesis (i.e., CHS7, CHS8, IFS1, and IFS2) in both soybean pods and seeds during their late reproductive stage (i.e., R5-R8). Isoflavone concentrations were quantified using high-performance liquid chromatography (HPLC), and gene expression was studied using quantitative real-time (qRT)-PCR. High-temperature stress [33/25 °C (day/night temperatures)] imposed at the late reproductive stage (R5-R8) reduced total isoflavone concentration by 46-86 and 20-73% in seeds and pods, respectively, the reduction depending on the stage of maturity. At stage R5, the reduction in total isoflavone concentration was greater in seeds than in pods, whereas at subsequent stages, the reverse was observed. High-temperature stress had a large impact on the expression of CHS7, CHS8, IFS1, and IFS2 in both seeds and pods. In seeds, temperature stress reduced the expression of one gene at the R5 stage (CHS8), two genes at the R6 stage (CHS7 and IFS1), and all four genes at the R7 stage, the reduction ranging between 35 and 97%. In pods, high-temperature stress affected the expression of two genes at the R6 stage (CHS7 and IFS2) and all four genes at the R7 stage. Unlike in seeds, at the R6 stage, high temperature increased the expression of CHS7 and IFS2 by 72 and 736%, respectively, whereas at R7 stage the expression of all genes was reduced by an average of 97%. The present study reveals that high-temperature stress initiated at the R5 stage and maintained until maturation (i.e., R8 stage) has a rapid and sustained negative effect on isoflavone concentration in both seeds and pods. High temperature also affects gene expression; however, there was no clear correlation between isoflavone concentration and gene expression.
异黄酮具有潜在的健康益处，这导致了人们对大豆和大豆制品的兴趣和需求增加。本研究旨在确定高温胁迫对大豆荚果和种子在生殖后期（即 R5-R8）中异黄酮浓度以及参与异黄酮合成的四个关键基因（CHS7、CHS8、IFS1 和 IFS2）表达的影响。使用高效液相色谱法（HPLC）定量异黄酮浓度，并用实时定量（qRT）-PCR 研究基因表达。在生殖后期（R5-R8）施加高温胁迫[33/25°C（白天/夜间温度）]，分别使种子和荚果中的总异黄酮浓度降低 46-86%和 20-73%，具体降低程度取决于成熟度。在 R5 期，种子中总异黄酮浓度的降低大于荚果，而在随后的阶段则相反。高温胁迫对种子和荚果中 CHS7、CHS8、IFS1 和 IFS2 的表达有很大影响。在种子中，温度胁迫在 R5 期降低了一个基因（CHS8）的表达，在 R6 期降低了两个基因（CHS7 和 IFS1）的表达，在 R7 期降低了所有四个基因的表达，降低幅度在 35-97%之间。在荚果中，高温胁迫在 R6 期影响了两个基因（CHS7 和 IFS2）的表达，在 R7 期影响了所有四个基因的表达。与种子不同的是，在 R6 期，高温分别使 CHS7 和 IFS2 的表达增加了 72%和 736%，而在 R7 期，所有基因的表达平均降低了 97%。本研究表明，从 R5 期开始并持续到成熟（即 R8 期）的高温胁迫对种子和荚果中的异黄酮浓度有快速和持续的负面影响。高温还会影响基因表达；然而，异黄酮浓度与基因表达之间没有明显的相关性。
