The sense and antisense expression of gibberellin 20-oxidase gene (rga5) in rice and its effects on GA_1 level and agronomic traits

摘要

A gibberellin 20-oxidase gene rga5 was isolated by PCR from genomic DNA of rice (Oryza sativa ssp indica) cultivars 慉izizhan?and 慛ante? Compared with the re-ported OsGA20ox, the rga5 was partial-frame-shifted with 11 different amino acids. Then the rga5 with CaMV 35S promotor and NOS terminator was inserted into the poly-linker site of pCambia1301 to construct sense and antisense gene expressing vectors pSrga5 and pArga5. The transgenic plants were obtained by biolistic bombardment with pSrga5 or pArga5. The transgenic rice plants showed that the over- expression and antisense-expression of rga5 have remarkable effects on the biological characters of rice. The sense trans-genic plants showed heightening with longer spike, more seed-bearing and unaffected flowering, whereas antisense transgenic plants showed dwarfing, early-flowering with slender stem, dark leaf color, shorter leaf and shorter spike. The PCR amplification and Southern blot hybridization showed that the rga5 has been integrated into the transgenic rice genome and the transcription of rga5 was identified by Northern blot hybridization. In the sense transgenic plants the GA1 content increased of about 50%, however, the an-tisense transgenic rice decreased of 90% approximately compared with control plant Zhonghua 8? These results demonstrated that the rga5 is a functional gene encoding gibberellin 20-oxidase in rice. Over-expressing rga5 signifi-cantly increases the endogenous GA1 level and plant height of rice, whereas the expression of antisense rga5 decreases the GA1 level and plant height of rice dramatically.