一种优良半矮秆水稻品种的分离与分子鉴定

Isolation and Molecular Characterization of Semi-dwarf Mutations in an Elite Rice Cultivar

株1S是中国南方稻区杂交水稻育种广泛应用的优良籼型温敏雄性核不育系.为了改良其农艺性状,我们采用体细胞无性系诱变方法筛选半矮秆突变体.本文报道了2个体细胞无性系突变体SV1S和SV14S的表型和初步分子鉴定结果.与亲本株1S相比,突变体的高度降低,基部节间长度缩短,节间壁显著增厚,但是上部的节间变化不明显.更重要的是,我们发现赤霉素生物合成途径中的关键酶基因GA20ox-2出现了约200bp的缺失突变,导致该基因在半矮秆突变体中的转录水平降低.研究结果表明,突变体SV1S和SV14S很可能是由于同一缺失突变导致赤霉素合成受阻,从而部分导致了半矮秆性状的出现.然而,2个突变体苗期的高度相同,以及糊粉层细胞!-淀粉酶活性和赤霉素敏感性降低等性状与以前报道的sd-1突变体有所不同.因此,我们推测在SV突变体中可能还存在第二个突变位点.该结果也进一步证实了体细胞无性系诱变在水稻育种中具有良好的应用前景.

Zhu1Sis an elite indicathermo-sensitive genic male-sterile breeding stock widely used in hybrid rice production in Southern China.To improve the key agronomic traits of this elite cultivar,somatic mutagenesis method was used to screen for semi-dwarf mutations.The phenotypic and preliminary molecu-lar characterization of two somatic mutants,named SV1Sand SV14S,was reported.Compared with the parent Zhu1S,these mutations have reduced plant statures,shortened and thickened the lower internodes significantly but the upper internodes slightly.Furthermore,we have found an approximate 200bp deletion in the GA20ox-2gene encoding the key GA metabolic enzyme and little transcription of this gene in both semi-dwarf mutant lines.These results have indicated that SV1Sand SV14S mutants are more likely impaired in gibberellin metabolism derived from the same mutation,which is partially responsible for their semi-dwarf phenotype.However,both mutants have similar height at the seedling stage and slightly reduce the GA sensitivity of amylase activity in aleurone cells,which is different from the previously reported sd-1mutants.Therefore,it is assumed that there is a second-site mutation in the SVmutants.Our results have further demonstrated the usefulness of somatic mutagenesis in the rice breeding program.