Department of Horticultural Sciences, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran.
Department of Plant Biotechnology, Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran.
Sci Rep. 2022 Jul 27;12(1):12827. doi: 10.1038/s41598-022-16887-9.
Milk thistle is an oil and medicinal crop known as an alternative oil crop with a high level of unsaturated fatty acids, which makes it a favorable edible oil for use in food production. To evaluate the importance of Milk thistle lipids in drought tolerance, an experiment was performed in field conditions under three different water deficit levels (Field capacity (FC), 70% FC and 40% FC). After harvesting seeds of the plant, their oily and methanolic extracts were isolated, and subsequently, types and amounts of lipids were measured using GC-MS. Genes and enzymes engaged in biosynthesizing of these lipids were identified and their expression in Arabidopsis was investigated under similar conditions. The results showed that content of almost all measured lipids of milk thistle decreased under severe drought stress, but genes (belonged to Arabidopsis), which were involved in their biosynthetic pathway showed different expression patterns. Genes biosynthesizing lipids, which had significant amounts were selected and their gene and metabolic network were established. Two networks were correlated, and for each pathway, their lipids and respective biosynthesizing genes were grouped together. Four up-regulated genes including PXG3, LOX2, CYP710A1, PAL and 4 down-regulated genes including FATA2, CYP86A1, LACS3, PLA2-ALPHA were selected. The expression of these eight genes in milk thistle was similar to Arabidopsis under drought stress. Thus, PXG3, PAL, LOX2 and CYP86A1 genes that increased expression were selected for protein analysis. Due to the lack of protein structure of these genes in the milk thistle, modeling homology was performed for them. The results of molecular docking showed that the four proteins CYP86A1, LOX2, PAL and PXG3 bind to ligands HEM, 11O, ACT and LIG, respectively. HEM ligand was involved in production of secondary metabolites and dehydration tolerance, and HEM binding site remained conserved in various plants. CA ligands were involved in synthesis of cuticles and waxes. Overall, this study confirmed the importance of lipids in drought stress tolerance in milk thistle.
水飞蓟是一种油用和药用作物，被称为高不饱和脂肪酸的替代油作物，是食品生产中一种受欢迎的食用油。为了评估水飞蓟脂类物质在耐旱性中的重要性，在田间条件下进行了一项实验，在三种不同的水分亏缺水平（田间持水量（FC）、70%FC 和 40%FC）下进行。在收获植物种子后，分离其油性和甲醇提取物，然后使用 GC-MS 测量脂质的类型和数量。鉴定参与这些脂质生物合成的基因和酶，并在类似条件下在拟南芥中研究它们的表达。结果表明，在严重干旱胁迫下，水飞蓟几乎所有测量脂质的含量都降低，但参与其生物合成途径的基因（属于拟南芥）表现出不同的表达模式。生物合成脂质的基因（含量较大）被选择，并建立了它们的基因和代谢网络。两个网络相关，对于每个途径，将它们的脂质和各自的生物合成基因分组在一起。选择了四个上调基因，包括 PXG3、LOX2、CYP710A1 和 PAL，以及四个下调基因，包括 FATA2、CYP86A1、LACS3 和 PLA2-ALPHA。在干旱胁迫下，这些基因在水飞蓟中的表达与拟南芥相似。因此，选择了表达增加的四个基因 PXG3、PAL、LOX2 和 CYP86A1 进行蛋白分析。由于水飞蓟中这些基因缺乏蛋白质结构，因此对它们进行了同源建模。分子对接的结果表明，四种蛋白质 CYP86A1、LOX2、PAL 和 PXG3 分别与配体 HEM、11O、ACT 和 LIG 结合。HEM 配体参与次生代谢产物的产生和耐旱性，并且 HEM 结合位点在各种植物中保持保守。CA 配体参与角质层和蜡质的合成。总的来说，这项研究证实了脂质在水飞蓟耐旱性中的重要性。
