Furutani Ikuyo, Sukegawa Shin, Kyozuka Junko
Graduate School of Agriculture and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo 113-0032, Japan.
Plant J. 2006 May;46(3):503-11. doi: 10.1111/j.1365-313X.2006.02703.x.
The basic structure of a rice inflorescence (the panicle) is determined by the pattern of branch formation, which is established at the early stages of panicle development. In this study we conducted global transcriptome profiling of the early stages of rice panicle development from phase transition to floral organ differentiation. To generate a meristem-specific gene-expression profile, shoot apical meristems (SAMs) and subsequently formed, very young panicles were collected manually and used for cDNA microarray analysis. We identified 357 out of 22,000 genes that are expressed differentially in the early stages of panicle development, and the 357 genes were classified into seven groups based on their temporal expression patterns. The most noticeable feature is that a fairly small number of genes, which are extensively enriched in transcription factors, are upregulated in the SAM immediately after phase transition. In situ hybridization analysis showed that each gene analysed exhibits a unique and interesting localization of mRNA. Remarkably, one of the transcription factors was proven to be a close downstream component of the pathway in which LAX, a major regulator of panicle branching, acts. These results suggest that our strategy--careful collection of meristems, global transcriptome analysis and subsequent in situ hybridization analysis--is useful not only to obtain a genome-wide view of gene expression, but also to reveal genetic networks controlling rice panicle development.
水稻花序（圆锥花序）的基本结构由分枝形成模式决定，这种模式在圆锥花序发育的早期阶段就已确立。在本研究中，我们对水稻圆锥花序从相变到花器官分化的早期阶段进行了全转录组分析。为了生成分生组织特异性基因表达谱，手动收集了茎尖分生组织（SAMs）以及随后形成的非常幼嫩的圆锥花序，并用于cDNA微阵列分析。我们在22000个基因中鉴定出357个在圆锥花序发育早期差异表达的基因，这357个基因根据其时间表达模式被分为七组。最显著的特征是，相当少数的基因，这些基因在转录因子中大量富集，在相变后立即在SAM中上调。原位杂交分析表明，所分析的每个基因都表现出独特且有趣的mRNA定位。值得注意的是，其中一个转录因子被证明是圆锥花序分枝主要调节因子LAX所作用的途径中的一个紧密下游成分。这些结果表明，我们的策略——仔细收集分生组织、全转录组分析以及随后的原位杂交分析——不仅有助于获得全基因组范围的基因表达视图，还能揭示控制水稻圆锥花序发育的遗传网络。
