同源异型域（Homeobox，HB）转录因子对于植物的生长发育具有重要的调控作用，主要涉及细胞分化、形态建成、内外环境信号应答等多个方面。为了研究该转录因子家族成员在水稻中的功能，构建了该家族成员OsHox9基因的RNAi表达载体，利用反向遗传方法分析该基因的功能。与野生型对照植株相比，RNAi转基因植株株高变矮，分蘖数减少。实时PCR表达分析表明OsHox9基因在有表型转基因植株中的表达下调，但在没有表型转基因植株中OsHox9表达量与野生型植株差异不显著，说明RNAi载体起到了干涉作用，转基因植株的表型是由RNAi造成的。组织特异性表达分析表明OsHox9在水稻的根、茎、叶、茎顶端分生组织及不同时期的幼穗中均有表达，但在茎顶端分生组织及幼穗中表达量较高。为了查明OsHox9的亚细胞定位，构建了OsHox9与绿色荧光蛋白GFP的融合载体并导入烟草叶片中进行瞬时表达，结果表明OsHox9定位于细胞膜上，在细胞膜上起作用。
The homeobox transcription factors play important roles in the growth and development of the plants, involved in regulation of cell differentiation, the architecture of morphogenesis and response to environmental signals in plants. To study the function of these transcription factors in rice, we constructed RNAi vectors of OsHox9 and analyzed the function of OsHox9 by the reverse genetics method. The results showed that the height and tiller number of RNAi transgenic plants were decreased in comparison with wild type plants. Realtime PCR analysis showed that OsHox9 expression level was downregulated in transgenic plants with phenotype. However, the expression level of OsHox9 in transgenic plants without phenotype was similar to wild type plants, suggesting that the phenotypes of transgenic plants were caused by RNAi effects. In addition, we also analyzed the expression pattern of OsHox9 in different organs of rice. The results showed that OsHox9 was expressed in different organs, especially displayed high expression level in stem apical meristems and young panicles. To investigate the subcellular localization of OsHox9, we constructed the fused vector 35S::OsHox9GFP to introduce into leaves of tobacco. The transient expression result showed OsHox9 was localized on the cell membrane.
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