Pyridoxine is required for post-embryonic root development and tolerance to osmotic and oxidative stresses
Pyridoxine is required for post-embryonic root development and tolerance to osmotic and oxidative stresses
复制标题
DOI：
10.1111/j.1365-313x.2005.02538.x
复制
发表时间：
2005-11-01
期刊：
影响因子：
7.2
通讯作者：
Xiong, LM
中科院分区：
文献类型：
--
作者：
Chen, H;Xiong, LM
吡哆醇（维生素B-6）是所有细胞生物体中许多酶所需的辅因子。植物是动物维生素B-6的主要来源，但植物中维生素B-6的生物合成途径和功能尚不清楚。在这项研究中，拟南芥吡哆醇合酶基因PDX 1的特点和其在体内的功能进行了研究。PDX 1基因在所有植物部位中均表达，其表达水平不受非生物胁迫或植物激素脱落酸的显著调节。在根中，PDX 1在经历快速细胞分裂的根尖后面的限定区域中高度表达。PDX 1蛋白主要与质膜和内膜相关，这意味着维生素B-6可能参与膜功能。为了揭示PDX 1在体内的作用，分离拟南芥插入突变体。引人注目的是，pdx 1基因敲除突变体的根生长和早期幼苗发育受损。根发育不良是由于细胞分裂和伸长减少所致。补充生长介质与吡哆醇或野生型PDX 1基因重新引入突变体完全恢复突变体的生长，表明PDX 1是必需的吡哆醇在植物中的生物合成。除了发育缺陷外，pdx 1突变体对渗透胁迫和氧化胁迫高度敏感。这些突变体幼苗在紫外线处理后，膜脂过氧化作用增强。我们的研究确定了维生素B-6在植物发育和胁迫耐受性中的关键作用，并表明维生素B-6可能代表植物中一类新的抗氧化剂。
Pyridoxine (vitamin B-6) is a cofactor required by numerous enzymes in all cellular organisms. Plants are the major source of vitamin B-6 for animals, yet the biosynthesis pathway and the function of vitamin B-6 in plants are not well elucidated. In this study, an Arabidopsis pyridoxine synthase gene PDX1 was characterized and its in vivo functions were investigated. The PDX1 gene was expressed in all plant parts examined and its expression level was not significantly regulated by abiotic stress or the phytohormone abscisic acid. In roots, PDX1 was highly expressed in a defined region behind the root tips that undergoes rapid cell division. The PDX1 protein was mainly associated with the plasma membrane and endomembranes, implying a potential involvement of vitamin B-6 in membrane function. To reveal the in vivo role of PDX1, Arabidopsis insertional mutants were isolated. Strikingly, the pdx1 knockout mutants were impaired in root growth and early seedling development. The stunted roots resulted from both reduced cell division and elongation. Supplementation of the growth media with pyridoxine or reintroduction of the wild-type PDX1 gene into the mutants completely restored the mutant growth, demonstrating that PDX1 is required for pyridoxine biosynthesis in planta. In addition to the developmental defects, pdx1 mutants are hypersensitive to osmotic stress and oxidative stress. These mutant seedlings had increased peroxidation of membrane lipids following UV treatment. Our study establishes a critical role of vitamin B-6 in plant development and stress tolerance and suggests that vitamin B-6 may represent a new class of antioxidant in plants.