Engineering cytokinin-related genes to enhance cytokinin level and using RNA interference-based gene silencing of CASBENE SYNTHASE 1 for seed detoxification in Jatropha curcas L.

• Main Authors: Hang Lin, 林涵
• Other Authors: 葉開溫
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/26030320614148540826

碩士 === 國立臺灣大學 === 植物科學研究所 === 102 === Jatropha curcas L. is one of the best candidates for biodiesel production owing to high oil content of seeds. However, there are several disadvantages, such as low seed yields and phorbol esters toxicity of seed cake for feedstuff use. Previous studies indicated that cytokinin spraying was able to promote cell division, repressed apical dominance and led to increase seed yield of J. curcas. Our preliminary study revealed that exogenous application of 6-benzyladenine on inflorescence caused phenotypical changes of numerous flowers and higher seed yield. Previous studies have shown that ISOPENTENYLTRANSFERASE and CYTOKININ OXIDASE were two genes playing the major roles in controlling endogenous cytokinin level and seed yield in plants. In order to increase endogenous cytokinin level in J. curcas, we have constructed CKX5-RNAi and 35S::JcIPT1 vectors based on the spatial expression profile of JcIPTs and JcCKXs and transformed to J. curcas mediated by A. tumefaciens. Data revealed the JcIPT1 expression level in 35S::JcIPT1 transgenic line 15 is much higher than empty-vector transformed J. curcas. The 35S::JcIPT1 transgenic line 1 has higher cytokinin level than empty-vector transformed J. curcas. In parallel, the seed detoxification by engineering JcCAS1-RNAi is in progress. Casbene synthases (CASs) catalyze the first step of phorbol ester (PE) biosynthesis. PEs are the main toxic compounds in J. curcas. Our spatial expression profile of JcCAS1 indicated that JcCAS1 had higher expression level in roots and germination seeds but did not express in leaves. The expression level of JcCAS1 increased towards fruit maturity. Thus far two transgenic lines were obtained.