The Plant Cell:發現植物花葯質體中脂肪酸代謝新途徑

上海交大張大兵教授研究團隊和美國、德國等科研小組合作，經過近7年的研究，克隆並鑑定了一個參與單子葉植物水稻花葯及花粉外壁發育的脂肪醯基載體蛋白還原酶（Fatty Acyl Carrier Protein Reductase ），DPW（Defective Pollen Wall），並提出了花葯表皮和花粉外壁發育新途徑（如下圖所示）。該研究成果發表在《植物細胞》（The Plant Cell，June 24, 2011）。

DPW參與的花粉外壁和花葯表皮層合成分子機制的示意圖

脂肪醇是一類廣泛地存在於植物、動物、藻類等生物體中的脂類分子，以游離態或者與其它分子結合態形式作為植物和昆蟲表皮、動物皮膚等組織結構的重要細胞組分。 長期以來，人們對於脂肪醇合成的生化分子機制了解甚少。花葯表皮和花粉外壁是植物雄性生殖細胞的重要的保護結構，該結構可保護花粉免受外界環境和病菌等侵害，花粉外壁物質在花粉和柱頭的相互識別過程中發揮重要的作用。

該研究揭示，DPW蛋白定位於質體中，重組蛋白可以脂肪醯基載體蛋白為底物，將C16脂肪酸還原為其相應的脂肪醇，從而參與花葯及花粉外壁的合成，並且通過遺傳互補等實驗證明DPW在雙子葉植物擬南芥中具有保守的生物學功能。這項研究證明了植物質體除了具有合成脂肪酸能力，還具備將脂肪酸轉化為脂肪醇的功能。另外，此前有報導認為動物和植物中的Fatty acid reductase (FAR)的底物是fatty-acyl CoAs, 該研究則證明了DPW（FAR類似蛋白）的最適底物為fatty acyl-ACP。（生物谷Bioon.com）

生物谷推薦原文出處：

The Plant Cell   doi: 10.1105/tpc.111.087528

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

Jing Shi, Hexin Tan, Xiao-Hong Yu, Yuanyun Liu, Wanqi Liang, Kosala Ranathunge, Rochus Benni Frank, Lukas Schreiber, Yujiong Wang, Guoying Kai, John Shanklin, Hong Ma, and Dabing Zhang

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.