山茶CjSAD1的克隆及其在耐寒中的作用

Cloning of Camellia japonica CjSAD1 and its role in cold tolerance

硬脂酰-ACP脱氢酶(stearoyl-ACP desaturase, SAD)是植物体内重要的脂肪酸去饱和酶之一。qRTPCR表达分析发现,山茶硬脂酰-ACP脱氢酶基因CjSAD1被低温迅速诱导表达。从山茶品种‘绛雪’中克隆了CjSAD1,该基因CDS长789 bp,编码263个氨基酸,具有2个典型的铁离子结合位点,属于类铁蛋白超家族成员。进化分析表明, CjSAD1蛋白与茶树、油橄榄等物种的同源蛋白亲缘关系较近。构建CjSAD1植物超量表达载体并转化拟南芥,转基因后代叶片不饱和脂肪酸组分发生改变, C18:1脂肪酸含量显著增加。对转基因植株进行-3℃低温胁迫处理,转基因植株胁迫后存活率显著高于野生型对照,且丙二醛和相对电导率的增加量明显低于野生型对照。上述结果表明山茶CjSDA1能够增强植物对低温的抗性,该研究为通过基因工程方法提高植物耐寒性提供了潜在的基因资源。

Stearoyl-ACP desaturase(SAD) is one of the most important fatty acid desaturase enzymes in plants. qRT-PCR analysis showed that a stearoyl-ACP desaturase gene CjSAD1 was rapidly induced by low temperature in Camellia japonica. CjSAD1 was then cloned from C. japonica cultivar ’Jiang Xue’. The CDS of CjSAD1 is 789 bp and encodes 263 amino acids. It has two typical ion binding sites and belongs to the ferritin-like superfamily. The phylogenetic analysis showed that CjSAD1 protein was closely related to homologous proteins in tea plant and Olea europaea. CjSAD1-overexpressing Arabidopsis plants showed a significantly increased content of fatty acid C18:1 in leaves. Furthermore, Cj SAD1-overexpressing lines showed a significantly higher survival rate than that of wild type(WT) under-3℃ cold stress. The increment of malondialdehyde and relative electrolyte leakage of CjSAD1-overexpressing lines under cold stress were lower than that of WT. These results indicated that CjSAD1 was able to enhance plant cold tolerance, and this gene would be of great significance to enhance plant cold tolerance by means of genetic engineering.