[show abstract][hide abstract] ABSTRACT: The rice height has been proposed to involve gibberellin biosynthesis. In order to regulate rice height, we suppressed expression
of OsGA20ox2 by the double-stranded RNA interference (RNAi) method. For this purpose, we constructed two different RNAi vectors, pCH1CK
and pCH12CK, then performed Agrobacterium-mediated transformation of rice varieties QX1 and Zhongzuo0201. The RNAi transgenic lines derived from pCH1CK and pCH12CK
demonstrated a clear reduction in height compared with the control plants (P < 0.01). The height of dwarf lines from pCH1CK and pCH12CK were about 75–84% and 54–74% of that of the control plants, respectively.
Transcripts for semi-dwarf lines from pCH1CK and pCH12CK were also reduced in comparison with the control plants. Analyses
of seeds per panicle, 1,000-grain weight, and seed yield per plant suggested that the RNAi semi-dwarf lines showed stable
grain yield compared with the wild-type plants. We further showed that the RNAi semi-dwarf lines could be restored to normal
plant height by applying exogenous GA3. The results also indicate that different fragment of the same RNAi target can be practically applied to produce different
extent semi-dwarf of rice plants.
–Rice (Oryza sativa L.)–RNAi–Semi-dwarfism
[show abstract][hide abstract] ABSTRACT: GA 20-oxidase (GA20ox) is a regulatory enzyme for the syntheses of biologically active GAs in plants. The loss-of-function
mutations in OsGA20ox2 of rice (Oryza sativa L.) generate the well-known Green Revolution gene sd-1, which cause the semi-dwarfism phenotype. In our present investigation, semi-dwarf plants were generated from a taller rice
variety QX1 by RNAi suppression on the expression of OsGA20ox2. The 531bp-fragment of OsGA20ox2 was amplified by PCR from genomic DNA of QX1 and used to construct the hairpin RNAi vector pCQK2. The wild type QX1 was transformed
with pCQK2 by Agrobacterium-mediated transformation and some independent transgenic RNAi lines exhibited semi-dwarfism. RT-PCR and Northern blot analyses
showed that the expression of OsGA20ox2 was specifically suppressed in the RNAi semi-dwarf lines. Endogenous GA assays revealed that the contents of the GA20ox2-catalyzed
products GA19, GA20 and the down-stream biologically active GA1 were drastically reduced in the RNAi semi-dwarf lines. We further showed that the RNAi semi-dwarf lines could be restored
to normal plant height by applying exogenous GA3. The results indicated that the semi-dwarfism of the RNAi semi-dwarf lines was associated with the decreased expression of
OsGA20ox2 gene and the reduced content of endogenous biologically active GA1. Analyses of panicle length, seeds per panicle and 1000-grain weight suggested that the RNAi semi-dwarf lines showed stable
grain yield compared with the wild type plants. It is demonstrated that the RNAi approach could be useful for plant breeding
purposes in the future.