Functional analysis of rice GA 2-oxidase 4、7 and 8

• Main Authors: Ting-Jen Hu, 胡庭臻
• Other Authors: Liang-Jwu Chen
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/qn4uz7

碩士 === 國立中興大學 === 分子生物學研究所 === 101 === Abstract GA 2-oxidases (GA2oxs) is a class of 2-oxoglutarate-dependent dioxygenases (2-ODDs), could deactivate bioactive and precursor form of Gibberellins (GAs) by 2β-hydroxylation. According to previous studies, 10 putative GA 2-oxidases are identified in rice genome; however, OsGA2ox4, OsGA2ox7 and GA2ox8 have not studied yet. In order to confirm whether the OsGA2ox4, OsGA2ox7 and GA2ox8 protein possessed the enzyme function of GA 2-oxidase, two approaches were used in this study. One approach was overexpressing the OsGA2ox4, OsGA2ox7 and GA2ox8 genes ecotopically in TNG67. The second approach was utilizing the T-DNA mutant OsGA2ox4ACT (M97597), OsGA2ox7ACT (M85372) and OsGA2ox8ACT (M61685) with the expectation of the target gene actived. The phenotype of GA deficiency in rice is dwarfism. Therefore, the plant height of transgenic plants differed to TNG67 suggest that whether OsGA2ox4, OsGA2ox7 and GA2ox8 protein possessed the enzyme function of GA 2-oxidase. The target gene were overexpressed in transgenic construct ubi:GA2ox4 and ubi:GA2ox7 but not in ubi:GA2ox8. The averge plant height of ubi:GA2ox4 was 5.4 cm, the plant height of ubi:GA2ox7 was 66 cm. The expression level of OsGA2ox4 was clearly associated to its plant height in ubi:OsGA2ox4. As for the ubi:OsGA2ox8 transgenic plant, the OsGA2ox8 gene was not overexpressed by ubiquitin promoter and the plant height was similar to TNG67. Therefore, the activity of OsGA2ox8 could not be identified in this approach. In the second approach, among three T-DNA mutants, OsGA2ox4Act (M97597) and OsGA2ox7Act (M85372) T-DNA mutant showed the same plant height as that of TNG67, but OsGA2ox8Act (M61685) showed semi-dwarf indicated OsGA2ox8 possessed the function of GA 2-oxidase. Taking together the result from transgenic and T-DNA mutant approach, I conclude that OsGA2ox4, OsGA2ox7 and OsGA2ox8 possessed enzyme function of GA 2-oxidase.