Plant J. 2012 Dec;72(6):869-81. doi: 10.1111/j.1365-313X.2012.05123.x.
Phyllotaxy is defined as the spatial arrangement of leaves on the stem. The mechanism responsible for this extremely regular pattern is one of the most fascinating enigmas in plant biology. In this study, we identified a gene regulating the phyllotactic pattern in rice. Loss-of-function mutants of the DECUSSATE (DEC) gene displayed a phyllotactic conversion from normal distichous pattern to decussate. The dec mutants had an enlarged shoot apical meristem with enhanced cell division activity. In contrast to the shoot apical meristem, the size of the root apical meristem in the dec mutants was reduced, and cell division activity was suppressed. These phenotypes indicate that DEC has opposite functions in the shoot apical meristem and root apical meristem. Map-based cloning revealed that DEC encodes a plant-specific protein containing a glutamine-rich region and a conserved motif. Although its molecular function is unclear, the conserved domain is shared with fungi and animals. Expression analysis showed that several type A response regulator genes that act in the cytokinin signaling pathway were down-regulated in the dec mutant. In addition, dec seedlings showed a reduced responsiveness to exogenous cytokinin. Our results suggest that DEC controls the phyllotactic pattern by affecting cytokinin signaling in rice.
叶序是指叶子在茎上的空间排列方式。负责这种极其规则模式的机制是植物生物学中最迷人的谜团之一。在这项研究中，我们鉴定了一个调控水稻叶序模式的基因。DECUSSATE (DEC) 基因的功能丧失突变体表现出叶序从正常的二列性到十字形的转换。dec 突变体具有增大的茎尖分生组织，细胞分裂活性增强。与茎尖分生组织相反，dec 突变体的根尖分生组织减小，细胞分裂活性受到抑制。这些表型表明 DEC 在茎尖分生组织和根尖分生组织中具有相反的功能。基于图谱的克隆表明 DEC 编码一种植物特异性蛋白，含有富含谷氨酰胺的区域和一个保守基序。尽管其分子功能尚不清楚，但保守结构域与真菌和动物共享。表达分析表明，在 dec 突变体中，几种在细胞分裂素信号通路中起作用的 A 型应答调节基因下调。此外，dec 幼苗对外源细胞分裂素的反应性降低。我们的结果表明，DEC 通过影响水稻中的细胞分裂素信号来控制叶序模式。
