Effects of Paclobutrazol on the Expression of Genes Involved in Female Flower Formation in Jatropha curcas L. flower buds.

Abstract

Jatropha curcas L. (Jatropha) is a potential plant whose seeds could be used for biofuel production from their seeds. However, Jatropha plants have less number of female flowers than number of male flowers which affects to lower seed yield. The application of plant growth retardant such as Paclobutrazol (PCB) can be used for increasing plant production in many plant species. This study was aimed to find out the potential genes controlling female flower formation in Jatropha by investigating the expression pattern of floral organ identity genes (ABCE model) and sex determination genes in Jatropha flower buds after PCB treatment. It was found that PCB was significantly increased the number of female flowers (p≤0.05) but, the number of male flowers was not different from that of the control group. As a result, the ratio of female to male flowers in PCB treatment was significantly (p≤0.05) higher than the control group. The effect of PCB on ABCE model genes and sex determination genes in Jatropha flower buds at 0, 4, and 24 hours after PCB treatment showed that ABCE model genes were significantly up-regulated at 4h (p≤0.05) and significantly down-regulated at 24h (p≤0.05). However, the expression pattern of genes in ABCE model were not different. We, therefore, hypothesized that genes involved in ABCE model could not be used to explain the mechanisms sexual determination of Jatropha flowers. The statistical analysis of the expression of TASSELSEED2 (JcTS2) genes to the number of male and female flowers showed that JcTS2 genes was negatively associated (r=-0.999; p≤0.05) with the number of female flowers. Therefore, JcTS2 might be a potential gene that controls female flower formation in Jatropha and might be used as a database for further improving Jatropha and other plants’ seed yield.