Effect of PCB to Expression of Genes Involved in GA Biosynthesis During Jatropha Seedling

Abstract

The expression of Gibberellin (GA) biosynthetic genes is of particular importance in promoting plant growth and development. Gibberellin inhibitors such as Paclobutrazol (PCB), interrupts ent-kaurene oxidase (KO) enzyme activity in the GA biosynthetic pathway which reduces plant height. Nonetheless, GA inhibitors may benefit harvesting and seed yield improvement. The affect of PCB on the expressions of Jatropha GA biosynthesis genes using semi-quantitative PCR was previously reported. However, the technique showed some limitations which was not able to determine the precise level of gene expression. In this study, the effects of PCB on plant height and GA content in Jatropha seedling were investigated. Gene expression of ent-kaurene oxidase (JcKO), GA 20-oxidase1 (JcGA20ox1), GA 20-oxidase2 (JcGA20ox2) and GA 3-oxidase (JcGA3ox) were determined by qPCR. Appearantly, PCB significantly reduced the plant heights shown by shortened stem length. The GA contents were significantly lower compared to the control. The studies on the GA biosynthesis genes revealed the incline and decline of relative mRNA abundance of JcKO, JcGA20ox1 and JcGA20ox2 during 0, 3 day after treatment (DAT) and one week after treatments, respectively. The JcGA3ox transcripts were not detected at 3 and 7 DAT. Principle component analysis (PCA) also comfirmed the importance of JcGA20ox1 for plant height during seedling develoment. The comparisons of the phenotypes and transcriprion levels of the PCB treatments and those of control indicated that GA biosynthesis genes contributed to developmental processes with specific expression patterns during the plant growth.