胡杨PePEX11基因参与调节盐胁迫下拟南芥的抗氧化能力

目的长期非生物逆境胁迫下，植物会产生过量活性氧并造成氧化损伤，过氧化物酶体能够通过清除活性氧来调节氧化还原平衡。PEX基因参与过氧化物酶体的生物发生和增殖，PEX11基因的过表达可促进过氧化物酶体增殖，对植物的抗氧化能力的提升具有重要意义。胡杨是研究木本植物中抗逆机制优良材料，本文旨在探究胡杨PEX11基因对非生物胁迫的响应。方法本研究首先以胡杨叶片cDNA为模板克隆获得PEX11基因，命名为PePEX11，并对PePEX11蛋白进行生物信息学分析，其次采用实时荧光定量PCR分析PePEX11在胡杨中的表达模式，同时构建植物表达pCAMBIA1301-35S::PePEX11转化拟南芥，最后检测盐胁迫条件下转PePEX11拟南芥的抗氧化能力。结果PePEX11基因cDNA全长543 bp，编码180个氨基酸，PePEX11蛋白具有多个跨膜结构域，在膜上发挥作用。实时荧光定量PCR分析表明，该基因在胡杨体的成熟叶中表达量最高，幼叶次之，茎中最少；胡杨PePEX11基因受盐胁迫上调表达。功能分析显示，在含有100 mmol/L NaCl的培养基上，转PePEX11基因拟南芥株系的根长均显著长于野生型；对盆土中的移栽后12 d的幼苗150 mmol/L NaCl盐处理2周，转基因株系表现为营养生长良好，耐盐性较强。超表达PePEX11基因能显著提高(P＜0.05)拟南芥多种抗氧化酶的活性。DAB组织染色结果表明，转基因株系叶片中H₂O₂的含量明显少于野生型。结论本研究从胡杨中克隆PePEX11基因，并证明PePEX11能够提高拟南芥在盐胁迫下的抗氧化能力，提升耐盐能力。 

PePEX11 functions in regulating antioxidant capacity of Arabidopsis thaliana under salt stress

ObjectivePlants produce excessive reactive oxygen species(ROS)and have to suffer serious oxidative damage when exposed to long-term abiotic stress. Peroxisomes can remove ROS and regulate the re-dox balance of cells. The PEX gene is involved in the biogenesis and proliferation of peroxisomes. Overexpressing PEX11 lines improve the proliferation of peroxisomes, which is important for the promotion of antioxidant capacity in plants.Populus euphratica is an optimal material for studying stress resistance mechanism in woody plants.Here we are going to explore the function of PEX11 in P.euphratica response to abiotic stress.MethodIn this study we isolated PEX11 gene from cDNA of P.euphratica leaves and named it as PePEX11, and bioinformatics tools were used to analyze PePEX11 protein, then qRT-PCR was used to analyze the expression pattern of PePEX11 in P.euphratica.Meanwhile, plant expression vector pCAMBIA1301-35S::PePEX11 was constructed, and Arabidopsis thaliana was transformed for detecting antioxidant capacity under salt stress.ResultThe results showed that PePEX11 had 543 bp in length and encoding 180 amino acids. PePEX11 protein had multiple transmembrane domains and may function at the membrane.qRT-PCR analysis showed that PePEX11 gene highly expressed in mature leaves, following by young leaves, and had least expression in stems. The expression level of PePEX11 gene was also up-regulated by salt stress. Function analysis of PePEX11 overexpression lines in Arabidopsis thaliana showed that the root of oxPePEX11 was significantly longer than that of the wild type when treated with 150 mmol/L NaCl in the medium.After two weeks of salt treatment in soil, PePEX11 overexpression lines had better vegetative growth, showing better salt tolerance phenotype. Overexpression of PePEX11 significantly(P < 0.05)increased the activities of several antioxidant enzymes in A. thaliana. In addition, DAB staining assay displayed that the content of H₂O₂ in leaves of oxPePEX11 was lower than wild type.ConclusionIn summary, we cloned PePEX11 from P. euphratica and proved that PePEX11 improved the antioxidant capacity under salt stress and confers salt tolerance in A. thaliana.