Key Laboratory of Horticultural Plant Biology of Ministry of Education, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China.
State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Agriculture, Guangxi University, Nanning 530004, China.
Molecules. 2021 Sep 13;26(18):5546. doi: 10.3390/molecules26185546.
Flavonoids are key secondary metabolites that are biologically active and perform diverse functions in plants such as stress defense against abiotic and biotic stress. In addition to its importance, no comprehensive information has been available about the secondary metabolic response of tree, especially the genes that encode key enzymes involved in flavonoid biosynthesis under drought stress. In this study, the quantitative real-time polymerase chain reaction (qRT-PCR) analysis revealed that the expression of flavonoid biosynthesis genes (, , , , , , and ) gradually increased in the leaves of hybrid poplar (. × . ), corresponding to the drought stress duration. In addition, the activity and capacity of antioxidants have also increased, which is positively correlated with the increment of phenolic, flavonoid, anthocyanin, and carotenoid compounds under drought stress. As the drought stress prolonged, the level of reactive oxygen species such as hydrogen peroxide (HO) and singlet oxygen (O) too increased. The concentration of phytohormone salicylic acid (SA) also increased significantly in the stressed poplar leaves. Our research concluded that drought stress significantly induced the expression of flavonoid biosynthesis genes in hybrid poplar plants and enhanced the accumulation of phenolic and flavonoid compounds with resilient antioxidant activity.
类黄酮是生物活性的主要次生代谢物，在植物中具有多种功能，如抵御生物和非生物胁迫的应激防御。除了其重要性之外，关于树木的次生代谢反应，特别是在干旱胁迫下编码参与类黄酮生物合成的关键酶的基因，还没有全面的信息。在这项研究中，定量实时聚合酶链反应（qRT-PCR）分析显示，杂种杨树（. ×. ）叶片中类黄酮生物合成基因（ 、 、 、 、 、 、 ）的表达随着干旱胁迫时间的延长而逐渐增加。此外，抗氧化剂的活性和能力也有所增加，这与干旱胁迫下酚类、类黄酮、花青素和类胡萝卜素化合物的增量呈正相关。随着干旱胁迫时间的延长，过氧化氢（HO）和单线态氧（O）等活性氧的水平也升高。在受胁迫的杨树叶片中，植物激素水杨酸（SA）的浓度也显著增加。我们的研究得出结论，干旱胁迫显著诱导了杂种杨树植物中类黄酮生物合成基因的表达，并增强了具有弹性抗氧化活性的酚类和类黄酮化合物的积累。
