State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
Biotechnology Research Institute/National Key Facility for Gene Resources and Gene Improvement, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
New Phytol. 2012 Oct;196(2):402-413. doi: 10.1111/j.1469-8137.2012.04270.x. Epub 2012 Aug 22.
The formation of diverse, appropriately patterned cell types is critical in the development of all complex multicellular organisms. In flowering plants, anther patterning is a complex process essential for successful sexual reproduction. However, few genes regulating this process have been characterized to date. We report here that the gene MICROSPORELESS2 (MIL2) regulates early anther cell differentiation in rice (Oryza sativa). The anthers of mil2 mutants were characterized using molecular markers and cytological examination. The MIL2 gene was cloned and its expression pattern was analyzed through RNA in situ hybridization. The localization of the MIL2 protein was observed by immunostaining. MIL2 encodes the rice homolog of the Arabidopsis TAPETUM DETERMINANT1 (TPD1) protein. However, mil2 anthers display phenotypes different from those of tpd1 mutants, with only two layers of anther wall cells formed. MIL2 has an expression pattern distinct from that of TPD1. Its transcripts and proteins predominate in inner parietal cells, but show little accumulation in reproductive cells. Our results demonstrate that MIL2 is responsible for the differentiation of primary parietal cells into secondary parietal cells in rice anthers, and suggest that rice and Arabidopsis anthers might share similar regulators in anther patterning, but divergent mechanisms are employed in these processes.
细胞类型的多样化和适当的模式形成对于所有复杂的多细胞生物的发育至关重要。在有花植物中，花药模式的形成是成功有性繁殖的关键过程。然而，迄今为止，已鉴定出的调节该过程的基因很少。我们在这里报告，MICROSPORELESS2（MIL2）基因调节水稻（Oryza sativa）早期花药细胞的分化。通过分子标记和细胞学检查来鉴定 mil2 突变体的花药。克隆了 MIL2 基因，并通过 RNA 原位杂交分析其表达模式。通过免疫染色观察 MIL2 蛋白的定位。MIL2 编码拟南芥 TAPETUM DETERMINANT1（TPD1）蛋白的水稻同源物。然而，mil2 花药表现出与 tpd1 突变体不同的表型，仅形成两层花药壁细胞。MIL2 的表达模式与 TPD1 不同。其转录本和蛋白主要在内部周缘细胞中积累，但在生殖细胞中积累很少。我们的结果表明，MIL2 负责水稻花药中初级周缘细胞向次级周缘细胞的分化，并表明水稻和拟南芥花药可能在花药模式形成中具有相似的调节因子，但在这些过程中采用了不同的机制。
