The sense and antisense expression of gibberellin 20-oxidase gene (rga5) in rice and its effects on GA1 level and agronomic traits

Abstract

A gibberellin 20-oxidase generga5 was isolated by PCR from genomic DNA of rice (Oryza sativa ssp indica) cultivars ‘Aizizhan’ and ‘Nante’. Compared with the reported OsGA20ox, therga5 was partial-frame-shifted with 11 different amino acids. Then therga5 with CaMV 35S promotor and NOS terminator was inserted into the polylinker 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 overexpression and antisense-expression ofrga5 have remarkable effects on the biological characters of rice. The sense transgenic 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 therga5 has been integrated into the transgenic rice genome and the transcription ofrga5 was identified by Northern blot hybridization. In the sense transgenic plants the GA1 content increased of about 50%, however, the antisense transgenic rice decreased of 90% approximately compared with control plant ‘Zhonghua 8’. These results demonstrated that therga5 is a functional gene encoding gibberellin 20-oxidase in rice. Over-expressingrga5 significantly increases the endogenous GA1 level and plant height of rice, whereas the expression of antisenserga5 decreases the GA1 level and plant height of rice dramatically.