小桐子赤霉素合成酶JcGA3ox基因家族成员的克隆与功能分析

Cloning and Functional Analysis of the Members of Gibberellin Biosynthesis Enzyme JcGA3ox Gene Family in Jatropha curcas

赤霉素(gibberellins,GAs)是一类在植物生长和发育过程中起重要调控作用的植物激素。本研究克隆了木本油料能源植物小桐子(Jatropha curcas)赤霉素3-氧化酶(gibberellin 3-oxidase,JcGA3ox)基因家族全部3个成员,分别命名为JcGA3ox1、JcGA3ox2和JcGA3ox3。采用RT-qPCR技术检测JcGA3oxs在成年小桐子不同组织部位的表达量,发现JcGA3ox1的主要表达部位是成熟叶和幼果;JcGA3ox2的主要表达部位是成熟叶、雌花和雄花;JcGA3ox3主要表达部位是根、成熟叶和幼果。为了进一步探究JcGA3oxs在植物生长和发育过程中的作用,采用35S启动子分别构建了35S:JcGA3ox1、35S:JcGA3ox2和35S:JcGA3ox3超量表达载体,并转化拟南芥和小桐子。结果显示,35S:JcGA3oxs转基因拟南芥和小桐子植株的JcGA3oxs表达水平均显著高于野生型植株。与野生型拟南芥植株相比,转基因拟南芥植株GA_(1)和GA3含量均有减少,GA_(4)、GA_(24)和GA_(34)含量均有增加。但35S:JcGA3oxs转基因拟南芥和小桐子植株未出现开花时间、茎秆伸长或花器官发育异常等由内源赤霉素过量引起的典型表型变化。本研究结果表明在木本植物小桐子中GA3ox可能不是影响活性赤霉素含量及其生理功能的主要代谢酶。

Gibberellins(GAs)are a class of plant hormones that play an important regulatory role in plant growth and development.In this study,the three members of GA3-oxidase(JcGA3ox)gene family from Jatropha curcas were cloned and named as JcGA3oxl,JcGA3ox2,and JcGA3ox3.The expression pattern of JcGA3oxs in different organs of adult Jatropha plants was analyzed by real-time fluorescence quantitative PCR(RT-qPCR),and it was found that JcGA3ox1 was mainly expressed in mature leaves and young fruits;while JcGA3ox2 in mature leaves,female flowers and male flowers;and JcGA 3ox3 in roots,mature leaves and young fruits.In order to further explore the function of GA3oxs in the growth and development of plants,the 35S promoter was used to drive the expression of the three JcGA3oxs in Arabidopsis thaliana and Jatropha.The results showed that although the expression of JcGA3oxs in the transgenic Arabidopsis and Jatropha plants were at high levels,there were no typical phenotypic changes,such as flowering time,stem elongation,or abnormal development of floral organs among WT and transgenic plants.Compared with wild-type Arabidopsis plants,the contents of GA_(1)and GA_(3)in transgenic Arabidopsis plants were reduced,while the contents of GA_(4),GA_(24)and GA34 were increased.Thus,the JcGA3oxs seem not to be the key enzymes involved in active GA3ox formation and therefore affecting physiological function in Jatropha.