Al-Quraan Nisreen A, Samarah Nezar H, Tanash Ayah A
Department of Biotechnology and Genetic Engineering, Faculty of Science and Arts, Jordan University of Science and Technology, Irbid 22110, Jordan.
Department of Plant Production, Faculty of Agriculture, Jordan University of Science and Technology, Irbid 22110, Jordan.
Funct Plant Biol. 2024 Jan;51(1):NULL. doi: 10.1071/FP22177.
Activation of γ-aminobutyric acid (GABA) shunt pathway and upregulation of dehydrins are involved in metabolic homeostasis and protective mechanisms against drought stress. Seed germination percentage, seedling growth, levels of GABA, alanine, glutamate, malondialdehyde (MDA), and the expression of glutamate decarboxylase (GAD ) and dehydrin (dhn and wcor ) genes were examined in post-germination and seedlings of four durum wheat (Triticum durum L.) cultivars in response to water holding capacity levels (80%, 50%, and 20%). Data showed a significant decrease in seed germination percentage, seedling length, fresh and dry weight, and water content as water holding capacity level was decreased. Levels of GABA, alanine, glutamate, and MDA were significantly increased with a negative correlation in post-germination and seedling stages as water holding capacity level was decreased. Prolonged exposure to drought stress increased the GAD expression that activated GABA shunt pathway especially at seedlings growth stage to maintain carbon/nitrogen balance, amino acids and carbohydrates metabolism, and plant growth regulation under drought stress. The mRNA transcripts of dhn and wcor significantly increased as water availability decreased in all wheat cultivars during the post-germination stage presumably to enhance plant tolerance to drought stress by cell membrane protection, cryoprotection of enzymes, and prevention of reactive oxygen species (ROS) accumulation. This study showed that the four durum wheat cultivars responded differently to drought stress especially during the seedling growth stage which might be connected with ROS scavenging systems and the activation of antioxidant enzymes that were associated with activation of GABA shunt pathway and the production of GABA in durum seedlings.
γ-氨基丁酸（GABA）分流途径的激活和脱水素的上调参与了代谢稳态以及干旱胁迫的保护机制。研究了四个硬粒小麦（Triticum durum L.）品种在发芽后和幼苗期，对应持水量水平（80%、50%和20%）下的种子发芽率、幼苗生长、GABA、丙氨酸、谷氨酸、丙二醛（MDA）水平以及谷氨酸脱羧酶（GAD）和脱水素（dhn和wcor）基因的表达。数据表明，随着持水量水平降低，种子发芽率、幼苗长度、鲜重和干重以及含水量显著下降。随着持水量水平降低，发芽后和幼苗期GABA、丙氨酸、谷氨酸和MDA水平显著增加且呈负相关。长期干旱胁迫会增加GAD表达，激活GABA分流途径，尤其是在幼苗生长阶段，以维持干旱胁迫下的碳/氮平衡、氨基酸和碳水化合物代谢以及植物生长调节。在发芽后阶段，随着所有小麦品种水分可利用性降低，dhn和wcor的mRNA转录本显著增加，推测这是通过细胞膜保护、酶的低温保护以及防止活性氧（ROS）积累来增强植物对干旱胁迫的耐受性。本研究表明，四个硬粒小麦品种对干旱胁迫的反应不同，尤其是在幼苗生长阶段，这可能与ROS清除系统以及抗氧化酶的激活有关，而抗氧化酶的激活与GABA分流途径的激活以及硬粒小麦幼苗中GABA的产生有关。
