Department of Plant Molecular Physiology, Centre of Biotechnology of Borj Cedria, Science and Technology Park, P.O. Box. 901, 2050, Hammam-Lif, Tunisia.
Protoplasma. 2022 Sep;259(5):1189-1203. doi: 10.1007/s00709-021-01733-y. Epub 2022 Jan 4.
Chitinases are pathogenesis-related proteins, which play an important role in plant growth regulation, defense mechanism, and stress tolerance. Embryogenic cultures from Vitis vinifera cv. Tempranillo exposed to in vitro stress exhibited the expression of an extracellular class IV endochitinase VvChit-IV. Phylogenetic and conserved motif analyses provided insights into the evolutionary relationships of chitinases. A computation-based investigation showed conserved domains and illustrated a chitin-binding site for chitin cleavage with a catalytic domain of glycoside hydrolase. Interestingly, gene expression pattern showed a differential expression of VvChit-IV associated with embryonic stress response to in vitro conditions. In response to in vitro stress, transcript level of VvChit-IV increased in embryogenic calli and cell suspensions and peaked at 1.5 and 3 folds, respectively, when compared to an internal reference gene. Evidence of tissue culture stress-induced endochitinase was reported here for the first time indicating that in vitro stress could mitigate elicitor application to induce chitinase expression and can stimulate an immune response against abiotic constraints. Data showed that up-regulation of VvChit-IV was associated with a substantial increase of HO and proline without significant change in malondialdehyde content suggesting that the HO signaling network might trigger a priming effect to boost the defense response against environmental stress. Endochitinase activation in plant stress mitigation was thus highlighted to improve tolerance through attenuation of oxidative stress. This study revealed that the grapevine endochitinase is promising for enhancing coping-oriented adaptation and abiotic stress tolerance, which gives new insights into its feasibility for use in cross-tolerance and crop improvement.
几丁质酶是与发病机制相关的蛋白质，在植物生长调控、防御机制和应激耐受中发挥重要作用。在体外胁迫下，葡萄品种 Tempranillo 的胚性培养物表现出细胞外 IV 类内切几丁质酶 VvChit-IV 的表达。系统发育和保守基序分析为几丁质酶的进化关系提供了深入了解。基于计算的研究表明了保守结构域，并说明了与几丁质裂解相关的几丁质结合位点，具有糖苷水解酶的催化结构域。有趣的是，基因表达模式显示出 VvChit-IV 的差异表达与胚胎对体外条件的应激反应有关。在体外胁迫下，与内部参考基因相比，胚性愈伤组织和细胞悬浮液中的 VvChit-IV 转录本水平分别增加了 1.5 倍和 3 倍。这里首次报道了组织培养应激诱导内切几丁质酶的证据，表明体外胁迫可以减轻诱导几丁质酶表达的激发子应用，并可以刺激对非生物胁迫的免疫反应。研究表明，VvChit-IV 的上调与 HO 和脯氨酸的大量增加有关，而丙二醛含量没有显著变化，这表明 HO 信号网络可能引发启动效应，以增强对环境胁迫的防御反应。因此，植物应激缓解中的内切几丁质酶的激活被强调为通过减轻氧化应激来提高耐受性。本研究表明，葡萄内切几丁质酶有望增强应对导向的适应和非生物胁迫耐受性，为其在交叉耐受和作物改良中的可行性提供了新的见解。
