表观遗传学

来自上海交通大学生命科学与技术学院的研究人员与美国、德国等科研小组展开合作在新研究中克隆并鉴定了一个参与单子叶植物水稻花药及花粉外壁发育的脂肪酰基载体蛋白还原酶（Fatty Acyl Carrier Protein Reductase ），DPW（Defective Pollen Wall），并提出了花药表皮和花粉外壁发育新途径。该研究成果发表在植物科学领域顶级期刊《植物细胞》（The Plant Cell）杂志上。

上海交通大学张大兵教授是这篇文章的通讯作者，其早年毕业于中国科学院上海植物生理生态所。

脂肪醇是一类广泛地存在于植物、动物、藻类等生物体中的脂类分子，以游离态或者与其它分子结合态形式作为植物和昆虫表皮、动物皮肤等组织结构的重要细胞组分。长期以来，人们对于脂肪醇合成的生化分子机制了解甚少。花药表皮和花粉外壁是植物雄性生殖细胞的重要的保护结构，该结构可保护花粉免受外界环境和病菌等侵害，花粉外壁物质在花粉和柱头的相互识别过程中发挥重要的作用。

新研究揭示，DPW蛋白定位于质体中，重组蛋白可以脂肪酰基载体蛋白为底物，将C16脂肪酸还原为其相应的脂肪醇，从而参与花药及花粉外壁的合成，并且通过遗传互补等实验证明DPW在双子叶植物拟南芥中具有保守的生物学功能。这项研究证明了植物质体除了具有合成脂肪酸能力，还具备将脂肪酸转化为脂肪醇的功能。另外，此前有报道认为动物和植物中的Fatty acid reductase (FAR)的底物是fatty-acyl CoAs, 该研究则证明了DPW（FAR类似蛋白）的最适底物为fatty acyl-ACP。

原文摘要：

Defective Pollen Wall Is Required for Anther and Microspore Development in Rice and Encodes a Fatty Acyl Carrier Protein Reductase

Abstract:

Aliphatic alcohols naturally exist in many organisms as important cellular components; however, their roles in extracellular polymer biosynthesis are poorly defined. We report here the isolation and characterization of a rice (Oryza sativa) male-sterile mutant, defective pollen wall (dpw), which displays defective anther development and degenerated pollen grains with an irregular exine. Chemical analysis revealed that dpw anthers had a dramatic reduction in cutin monomers and an altered composition of cuticular wax, as well as soluble fatty acids and alcohols. Using map-based cloning, we identified the DPW gene, which is expressed in both tapetal cells and microspores during anther development. Biochemical analysis of the recombinant DPW enzyme shows that it is a novel fatty acid reductase that produces 1-hexadecanol and exhibits >270-fold higher specificity for palmiltoyl-acyl carrier protein than for C16:0 CoA substrates. DPW was predominantly targeted to plastids mediated by its N-terminal transit peptide. Moreover, we demonstrate that the monocot DPW from rice complements the dicot Arabidopsis thaliana male sterile2 (ms2) mutant and is the probable ortholog of MS2. These data suggest that DPWs participate in a conserved step in primary fatty alcohol synthesis for anther cuticle and pollen sporopollenin biosynthesis in monocots and dicots.