LAP5 and LAP6 Encode Anther-Specific Proteins with Similarity to Chalcone Synthase Essential for Pollen Exine Development in Arabidopsis
LAP5 and LAP6 Encode Anther-Specific Proteins with Similarity to Chalcone Synthase Essential for Pollen Exine Development in Arabidopsis
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DOI：
10.1104/pp.110.157446
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发表时间：
2010-07-01
期刊：
影响因子：
7.4
通讯作者：
Sumner, Lloyd W.
中科院分区：
文献类型：
--
作者：
Dobritsa, Anna A.;Lei, Zhentian;Sumner, Lloyd W.
陆地植物的花粉粒已经进化出非常坚固的外壁，称为外壁，其保护花粉并与雌性柱头细胞相互作用。外壁由孢粉素组成，虽然这种生物聚合物的组成和合成还不清楚，但脂肪酸和酚类物质都可能是组分。在这里，我们描述了拟南芥（拟南芥）少粘性花粉（LAP 5）和LAP 6的突变，影响外壁的发展。任何一个基因的突变都会导致花粉外壁结构异常，而双突变体的花粉缺乏外壁沉积，随后塌陷，导致雄性不育。LAP 5和LAP 6编码花药特异性蛋白，与类黄酮生物合成的关键酶查尔酮合成酶具有同源性。lap 5和lap 6突变减少了发育中花药中类黄酮前体和类黄酮的积累，表明在花粉素酚类成分的合成中发挥作用。我们在体外功能分析的LAP 5和LAP 6使用4-香豆酰辅酶A产生双noryangonin（一种常见的报告脱轨产品的查耳酮合酶），而类似的体外分析使用脂肪酰辅酶A作为底物产生中链烷基吡喃酮。因此，在体外试验表明，LAP 5和LAP 6是多功能酶，并可能发挥作用，在花粉外壁中发现的脂肪酸和酚类化合物的合成。最后，LAP 5和一个参与脂肪酸羟基化的花药基因（CYP 703 A2）之间的遗传相互作用表明，它们在外壁产生中协同作用。
Pollen grains of land plants have evolved remarkably strong outer walls referred to as exine that protect pollen and interact with female stigma cells. Exine is composed of sporopollenin, and while the composition and synthesis of this biopolymer are not well understood, both fatty acids and phenolics are likely components. Here, we describe mutations in the Arabidopsis (Arabidopsis thaliana) LESS ADHESIVE POLLEN (LAP5) and LAP6 that affect exine development. Mutation of either gene results in abnormal exine patterning, whereas pollen of double mutants lacked exine deposition and subsequently collapsed, causing male sterility. LAP5 and LAP6 encode anther-specific proteins with homology to chalcone synthase, a key flavonoid biosynthesis enzyme. lap5 and lap6 mutations reduced the accumulation of flavonoid precursors and flavonoids in developing anthers, suggesting a role in the synthesis of phenolic constituents of sporopollenin. Our in vitro functional analysis of LAP5 and LAP6 using 4-coumaroyl-coenzyme A yielded bis-noryangonin (a commonly reported derailment product of chalcone synthase), while similar in vitro analyses using fatty acyl-coenzyme A as the substrate yielded medium-chain alkyl pyrones. Thus, in vitro assays indicate that LAP5 and LAP6 are multifunctional enzymes and may play a role in both the synthesis of pollen fatty acids and phenolics found in exine. Finally, the genetic interaction between LAP5 and an anther gene involved in fatty acid hydroxylation (CYP703A2) demonstrated that they act synergistically in exine production.