砂藓RcPLD基因的抗旱功能分析

砂藓(Racomitrium canescens)是一种具有极强耐脱水性的苔藓植物,编码磷脂酶D的基因RcPLD能够在砂藓的脱水和复水过程中产生显著的表达响应,它可能参与了砂藓的强耐脱水性功能。该研究使用已克隆的RcPLD编码序列构建拟南芥(Arabidopsis thaliana)过量表达转基因株系rcpld-oe,初步考察过表达株系的干旱胁迫耐受能力及其相关的生理生化指标,分析RcPLD增强拟南芥抗旱性的机制。结果表明:(1)利用已克隆的RcPLD编码序列构建了植物中的过表达载体,成功构建了RcPLD的过表达转基因拟南芥株系rcpld-oe,并获得了多个T_3代rcpld-oe纯合体株系。(2)在正常生长条件下,rcpld-oe株系T_3代纯合体植株比野生型拟南芥植株体积小,但营养生长期较长,抽薹较晚,莲座叶衰老速率较慢;在干旱处理条件下,rcpld-oe株系表现出比野生型拟南芥更强的干旱耐受能力。(3)在干旱胁迫处理过程中,rcpld-oe株系莲座叶的水分散失速率降低,可能在一定程度上降低了干旱对膜完整性的损伤和光合作用的抑制,但其渗透调节物质含量的变化相对较小。研究发现,在干旱胁迫条件下,rcpld-oe植株莲座叶的水分散失速率和光合作用抑制程度显著降低,从而表现出明显强于野生型的干旱耐受能力,这为后续RcPLD功能的深入研究和更多砂藓抗旱功能基因的挖掘奠定了基础。

Analysis of Drought resistance Function of RcPLD Gene from Racomitrium canescens

Racomitrium canescens is a bryophyte with extremely strong desiccation tolerance. The gene RcPLD from R. canescens was annotated coding a phospholipase D protein performed significant expression responses in the desiccation and rehydration processes, and supposed maybe participated in the strong desiccation tolerance function of R. canescens. In this study, the cloned coding sequence of RcPLD was used for constructing the overexpression transgenic Arabidopsis thaliana lines rcpld oe, the mechanism of the drought resistance in A. thaliana enhanced by RcPLD was preliminary analyzed by determining the drought stress tolerance and related physiological and biochemical indexes. The results showed: (1) the cloned coding sequence of RcPLD was used for constructing plant overexpression vector, the RcPLD overexpression transgenic A. thaliana lines, rcpld oe, were successfully constructed, and many T₃ generation homozygote rcpld oe lines were obtained. (2) Under normal condition, T₃ generation homozygote rcpld oe lines performed smaller size, longer vegetative period, delayed bolting, and slower aging of rosette leaves comparing with wild type plants; under the condition of drought treatments, rcpld oe plants performed significantly better drought tolerance than the wild type A. thaliana. (3) In the process of drought treatments, it was found the water loss rate was lowered in rcpld oe plants, damage on membrane integrity and inhibition of photosynthesis maybe decreased to a certain extent, but little was affected on the content of osmotic regulation substance. According to the research, under the condition of drought stress, water loss and photosynthesis inhibition in the rosette leaves of rcpld oe plants were decreased, then performed the drought tolerance which was stronger than the wild type A. thaliana. This laid research foundations for further researching more functions of RcPLD and discovering more drought resistance function related genes in R. canescens.