桑树渗调蛋白基因的克隆及表达和功能分析

Cloning,Expression and Function Analysis of Mulberry Osmotin Gene

逆境胁迫是影响桑树生长发育的重要因素,渗调蛋白(osmotin,OSM)在植物响应逆境胁迫过程中具有重要的调节作用,鉴定桑树渗调蛋白基因,研究其功能和作用机制可以为桑树抗性育种提供基因资源,对促进桑树功能基因组研究具有重要意义。以生长45 d的丰驰桑幼苗为材料,克隆了桑树渗调蛋白基因MaOsm,并采用qRT-PCR方法分析该基因的组织表达模式和在非生物胁迫(干旱、盐、脱落酸和冷胁迫)下的诱导表达模式。结果显示,MaOsm基因在根、花、叶、芽中均有表达,其中在根和花中的表达水平较高;干旱、盐、脱落酸和冷胁迫均可诱导其表达,且在干旱胁迫下MaOsm基因表达显著上调。将MaOsm基因转入拟南芥中超表达发现,干旱胁迫后转基因植株的生长状态显著优于野生型;与野生型相比,转基因拟南芥植株叶片中脯氨酸含量显著升高,丙二醛含量降低,叶绿素含量降低幅度较小。研究结果表明,桑树渗调蛋白可能通过上调渗透调节物质的含量降低干旱胁迫对细胞膜的伤害,从而提高了桑树对干旱胁迫的耐受性,在桑树应答干旱胁迫中起重要作用。

Adversity stress is an important factor affecting the development of mulberry tree. Osmotins(OSMs)play critical roles in regulating plant resistance to adverse stress. It is of great significance to identify OSM genes from mulberry tree and study on its functional mechanism,which could provide gene resource for breeding mulberry tree resistant to adverse stress,and promote the research on mulberry functional genomics. In this study,mulberry OSM gene MaOsm was cloned from 45-day seedlings of mulberry Fengchi,and tissue expression pattern and stress-induced expression profile under abiotic stresses(drought,salt,abscisic acid and cold)were analyzed by qRT-PCR. The results showed that MaOsm was expressed in root,flower,leaf and bud,and the highest expression level was found in root and flower. Expression of MaOsm could all be induced under the stress of drought,salt,abscisic acid and cold,and the most significant up-regulation of MaOsm was found under drought stress. Compared with wild-type Arabidopsis thaliana,overexpression of MaOsm in A. thaliana significantly enhanced the growth of transgenic A. thaliana under drought stress. Besides,proline content in leaf of transgenic A. thaliana increased significantly,while malondialdehyde content decreased,and chlorophyll content decreased insignificantly. All above results indicate that MaOsm protects plant cells from drought stress by up-regulating the content of osmotic substances,and thereby increases drought tolerance of mulberry. In summary,MaOsm plays an important role in mulberry response to drought stress.