Abstract：
Phosphoenolpyruvate carboxylase (PEPC) plays a crucial role in the initial carbon fixation process in C4 plants. However, its nonphotosynthetic functions in Haloxylon ammodendron, a C4 perennial xerohalophytic shrub, are still poorly understood. Previous studies have reported the involvement of PEPC in plant responses to abiotic stresses such as drought and salt stress. However, the underlying mechanism of PEPC tolerance to drought stress has not been determined. In this study, we cloned the C4-type PEPC gene HaPEPC1 from H. ammodendron and investigated its biological function by generating transgenic Arabidopsis plants with ectopic expression of HaPEPC1. Our results showed that, compared with WT (wild-type) plants, ectopic expression of HaPEPC1 plants exhibited significantly greater germination rates and chlorophyll contents. Furthermore, under drought stress, the transgenic plants presented increased root length, fresh weight, photosynthetic capacity, and antioxidant enzyme activities, particularly ascorbate peroxidase and peroxidase. Additionally, the transgenic plants exhibited reduced levels of malondialdehyde, H2O2 (hydrogen peroxide), and O2- (superoxide radical). Transcriptome analysis indicated that ectopic expression of HaPEPC1 primarily regulated the expression of genes associated with the stress defence response, glutathione metabolism, and abscisic acid (ABA) synthesis and signalling pathways in response to drought stress. Taken together, these findings suggest that the ectopic expression of HaPEPC1 enhances the reduction of H2O2 and O2- in transgenic plants, thereby improving reactive oxygen species (ROS) scavenging capacity and enhancing drought tolerance. Therefore, the HaPEPC1 gene holds promise as a candidate gene for crop selection aimed at enhancing drought tolerance.
摘要：
磷酸烯醇丙酮酸羧化酶（PEPC）在C4植物的初始碳固定过程中起着至关重要的作用。然而,它在梭梭中的非光合功能，一种C4多年生干盐生灌木，仍然知之甚少。先前的研究报道了PEPC参与植物对非生物胁迫如干旱和盐胁迫的反应。然而,PEPC对干旱胁迫的耐受机制尚未确定。在这项研究中,我们从H.ammodendron中克隆了C4型PEPC基因HaPEPC1，并通过产生具有HaPEPC1异位表达的转基因拟南芥植物来研究其生物学功能。我们的研究结果表明,与WT（野生型）植物相比，HaPEPC1植物的异位表达显示出显着更高的发芽率和叶绿素含量。此外，在干旱胁迫下，转基因植物呈现增加的根长度，鲜重,光合能力，和抗氧化酶活性，特别是抗坏血酸过氧化物酶和过氧化物酶。此外,转基因植物的丙二醛水平降低，H2O2（过氧化氢），和O2-(超氧自由基)。转录组分析表明，HaPEPC1的异位表达主要调节与应激防御反应相关的基因的表达，谷胱甘肽代谢，以及响应干旱胁迫的脱落酸（ABA）合成和信号通路。一起来看,这些发现表明HaPEPC1的异位表达增强了转基因植物中H2O2和O2的减少，从而提高活性氧（ROS）清除能力，增强耐旱性。因此,HaPEPC1基因有望成为旨在增强耐旱性的作物选择的候选基因。
