Sdt97: A Point Mutation in the 5' Untranslated Region Confers Semidwarfism in Rice.

Sdt97: A Point Mutation in the 5' Untranslated Region Confers Semidwarfism in Rice.

Semidwarfism is an important agronomic trait in rice breeding programs. The semidwarf mutant gene Sdt97 was previously described. However, the molecular mechanism underlying the mutant is yet to be elucidated. In this study, we identified the mutant gene by a map-based cloning method. Using a residual heterozygous line (RHL) population, Sdt97 was mapped to the long arm of chromosome 6 in the interval of nearly 60 kb between STS marker N6 and SNP marker N16 within the PAC clone P0453H04. Sequencing of the candidate genes in the target region revealed that a base transversion from G to C occurred in the 5′ untranslated region of Sdt97. qRT-PCR results confirmed that the transversion induced an obvious change in the expression pattern of Sdt97 at different growth and developmental stages. Plants transgenic for Sdt97 resulted in the restoration of semidwarfism of the mutant phenotype, or displayed a greater dwarf phenotype than the mutant. Our results indicate that a point mutation in the 5′ untranslated region of Sdt97 confers semidwarfism in rice. Functional analysis of Sdt97 will open a new field of study for rice semidwarfism, and also expand our knowledge of the molecular mechanism of semidwarfism in rice.

半矮化是水稻育种计划中的一个重要农艺性状。半矮化突变基因Sdt97此前已有描述。然而，该突变的分子机制尚未阐明。在本研究中，我们通过基于图谱的克隆方法鉴定了该突变基因。利用剩余杂合系（RHL）群体，将Sdt97定位到第6号染色体长臂上，位于PAC克隆P0453H04内STS标记N6和SNP标记N16之间近60kb的区间。对目标区域内候选基因的测序显示，Sdt97的5′非翻译区发生了从G到C的碱基颠换。实时定量PCR（qRT - PCR）结果证实，这种颠换导致Sdt97在不同生长发育阶段的表达模式发生明显变化。转Sdt97基因的植株使突变体表型的半矮化得以恢复，或者表现出比突变体更矮的表型。我们的研究结果表明，Sdt97的5′非翻译区的一个点突变赋予了水稻半矮化特性。Sdt97的功能分析将为水稻半矮化研究开辟一个新领域，同时也将拓展我们对水稻半矮化分子机制的认识。