Department of Environmental Stress Biology, Institute of Plant Genetics, Polish Academy of Sciences, Strzeszyńska 34, Poznań 60-479, Poland.
Department of Molecular Physiology, Max-Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, Potsdam-Golm 14476, Germany.
Plant Cell Physiol. 2022 Mar 11;63(3):353-368. doi: 10.1093/pcp/pcac003.
Triacylglycerol is a key lipid compound involved in maintaining homeostasis of both membrane lipids and free fatty acids (FFA) in plant cells under adverse environmental conditions. However, its role in the process of lipid remodeling has not been fully recognized, especially in monocots, including grass species. For our study, two closely related introgression forms of Lolium multiflorum (Italian ryegrass) and Festuca arundinacea (tall fescue), distinct in their level of drought tolerance, were selected as plant models to study rearrangements in plant lipidome under water deficit and further re-watering. The low drought tolerant (LDT) form revealed an elevated level of cellular membrane damage accompanied by an increased content of polyunsaturated FFA and triacylglycerol under water deficit, compared with the high drought tolerant (HDT) form. However, the LDT introgression form demonstrated also the ability to regenerate its membranes after stress cessation. The obtained results clearly indicated that accumulation of triacylglycerol under advanced drought in the LDT form could serve as a cellular protective mechanism against overaccumulation of toxic polyunsaturated FFA and other lipid intermediates. Furthermore, accumulation of triacylglycerol under drought conditions could serve also as storage of substrates required for further regeneration of membranes after stress cessation. The rearrangements in triacylglycerol metabolism were supported by the upregulation of several genes, involved in a biosynthesis of triacylglycerol. With respect to this process, diacylglycerol O-acyltransferase DGAT2 seems to play the most important role in the analyzed grasses.
三酰基甘油是一种关键的脂质化合物，在植物细胞中，它在逆境条件下参与膜脂和游离脂肪酸（FFA）的动态平衡。然而，它在脂质重塑过程中的作用尚未得到充分认识，特别是在单子叶植物中，包括草类。在我们的研究中，选择了两种密切相关的多花黑麦草（意大利黑麦草）和高羊茅（高羊茅）的导入系形式作为植物模型，研究在水分亏缺和进一步复水条件下植物脂类组的重排。与高耐旱（HDT）形式相比，低耐旱（LDT）形式在水分亏缺下表现出更高水平的细胞膜损伤，同时多不饱和 FFA 和三酰基甘油含量增加。然而，LDT 导入系在胁迫停止后也表现出了再生其膜的能力。研究结果清楚地表明，在 LDT 形式的晚期干旱下三酰基甘油的积累可以作为一种细胞保护机制，防止有毒多不饱和 FFA 和其他脂质中间产物的过度积累。此外，在干旱条件下三酰基甘油的积累也可以作为胁迫停止后进一步再生膜所需的底物的储存。三酰基甘油代谢的重排得到了几个参与三酰基甘油生物合成的基因上调的支持。就这个过程而言，二酰基甘油 O-酰基转移酶 DGAT2 似乎在分析的草类中起着最重要的作用。
