Integrated -omics and functional study of the cell wall folding mechanism in resurrection plants

缺水是对作物产量产生负面影响的最严重的胁迫因素之一，预计未来几十年干旱时期的发生将会增加。为了能够将这些知识转移到旨在提高作物抗旱性的生物技术计划中，了解抗旱机制是至关重要的。细胞壁和质膜受到水分损失和随后的膨压损失的物理影响，这些结构的破坏会导致渗漏，最终导致细胞死亡。在这种背景下，复活植物，即具有非凡的生存能力的植物，已经被研究，以破译它们能够承受极端干旱的机制。目前的项目假设，细胞壁蛋白质组及其多糖组成的变化使复活植物(即植物红景天)能够耐受因相对含水量损失95%以上而造成的机械张力，并允许在脱水/复水循环中折叠、展开。随后质膜的脂质成分和蛋白质组的变化允许在氧化应激和组织干燥的情况下保持其完整性。为了验证这一假说，重点将放在细胞壁和质膜的亚细胞特征上：蛋白质组将在水合、脱水和复水状态下进行分析。为了补充这些数据集，细胞壁的组成将通过成像、免疫学和化学分析来表征，质膜的脂组成将在相同的生理状态下进行测定。此外，还将利用前面步骤中描述的一些基因在烟草和遭受干旱的植物愈伤组织中的过表达来验证在细胞壁和质膜上获得的结果的功能。

Water shortage is one of the most dramatic stress factors negatively impacting crop yield, and the occurrence of drought periods is foreseen to increase in the next decades. It is of the utmost importance to understand the mechanisms involved in drought tolerance to be able to transfer this knowledge in biotechnological programs aimed at improving crop tolerance to drought. Cell walls and plasma membranes are physically affected upon water loss and the subsequently loss of turgor pressure, and breakage of these structures leads to leakages and ultimately cell death. In this context, resurrection plants, i.e. plants with remarkable ability to survive extreme desiccation, have been studied to decipher the mechanisms by which they are able to withstand extreme desiccation. The current project hypothesizes that changes in the cell wall proteome and its polysaccharide composition enable resurrection plants (i.e. Craterostigma plantagineum) to tolerate the mechanical tension (due to turgor loss) caused by a loss of more than 95% of their relative water content and allow folding, unfolding during dehydration/rehydration cycle. Subsequent changes in the lipid composition and the proteome of the plasma membranes are allowing the preservation of its integrity despite oxidative stress and tissue desiccation. In order to test this hypothesis, the focus will be put on subcellular characterization of the cell wall and the plasma membrane: the proteomes will be analysed during hydrated, dehydrated, rehydrated states. To complement these datasets, the composition of the cell wall will be characterized by imaging, immunological and chemical assays and the lipid composition of the plasma membrane will be determined in the same physiological states. A functional analysis will also be performed to validate the results obtained in cell wall and plasma membrane using overexpression of some genes described in previous steps in tobacco and C. plantagineum calli submitted to drought.