School of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
Plant Physiol. 2010 Sep;154(1):149-62. doi: 10.1104/pp.110.158865. Epub 2010 Jul 7.
Synthesis of lipidic components in anthers, including of the pollen exine, is essential for plant male reproductive development. Plant lipid transfer proteins (LTPs) are small, abundant lipid-binding proteins that have the ability to exchange lipids between membranes in vitro. However, their biological role in male reproductive development remains less understood. Here, we report the crucial role of OsC6 in regulating postmeiotic anther development in rice (Oryza sativa). Found in monocots, OsC6 belongs to a distinct clade from previously identified LTP1 and LTP2 family members found in both dicots and monocots. OsC6 expression is mainly detectable in tapetal cells and weakly in microspores from stage 9 to stage 11 of anther development. Immunological assays indicated that OsC6 is widely distributed in anther tissues such as the tapetal cytoplasm, the extracellular space between the tapetum and middle layer, and the anther locule and anther cuticle. Biochemical assays indicated that recombinant OsC6 has lipid binding activity. Moreover, plants in which OsC6 was silenced had defective development of orbicules (i.e. Ubisch bodies) and pollen exine and had reduced pollen fertility. Furthermore, additional evidence is provided that the expression of OsC6 is positively regulated by a basic helix-loop-helix transcription factor, Tapetum Degeneration Retardation (TDR). Extra granule-like structures were observed on the inner surface of the tdr tapetal layer when the expression of OsC6 was driven by the TDR promoter compared with the tdr mutant. These data suggest that OsC6 plays a crucial role in the development of lipidic orbicules and pollen exine during anther development in rice.
花药中脂质成分的合成，包括花粉外壁，对植物雄性生殖发育至关重要。植物脂质转移蛋白（LTP）是一种小而丰富的脂质结合蛋白，能够在体外将脂质在膜之间交换。然而，它们在雄性生殖发育中的生物学作用仍知之甚少。在这里，我们报告了 OsC6 在调控水稻（Oryza sativa）减数分裂后花药发育中的关键作用。OsC6 存在于单子叶植物中，属于与先前在双子叶植物和单子叶植物中发现的 LTP1 和 LTP2 家族成员不同的独特分支。OsC6 的表达主要可检测到在绒毡层细胞中，在花药发育的 9 到 11 期的小孢子中表达较弱。免疫测定表明，OsC6 在花药组织中广泛分布，如绒毡层细胞质、绒毡层和中层之间的细胞外空间以及花药腔和花药表皮。生化测定表明，重组 OsC6 具有脂质结合活性。此外，沉默 OsC6 的植物具有 orbicules（即 Ubisch 体）和花粉外壁发育缺陷，花粉育性降低。此外，还提供了额外的证据表明，OsC6 的表达受到碱性螺旋-环-螺旋转录因子 Tapetum Degeneration Retardation（TDR）的正向调控。与 tdr 突变体相比，当 OsC6 的表达由 TDR 启动子驱动时，在 tdr 绒毡层的内表面观察到额外的颗粒状结构。这些数据表明，OsC6 在水稻花药发育过程中脂质 orbicules 和花粉外壁的发育中起关键作用。
