Conserved metabolic steps for sporopollenin precursor formation in tobacco and rice
Conserved metabolic steps for sporopollenin precursor formation in tobacco and rice
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DOI：
10.1111/ppl.12018
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发表时间：
2013-09-01
影响因子：
6.4
通讯作者：
Lo, Clive
中科院分区：
文献类型：
--
作者：
Wang, Yanbing;Lin, Ying-Chen;Lo, Clive
花粉壁的发育和适当的孢粉素沉积是有花植物花粉生活力和雄性育性所必需的。孢粉素是由脂肪酸和酚类衍生物合成的复杂生物聚合物。最近在拟南芥中的研究已经确定了一些花药特异性基因，这些基因参与了外壁形成所需的脂肪酰基单体的产生。孢粉素生物合成的古老生物化学途径的存在已被广泛提出，但实验证据以外的植物物种拟南芥是不广泛。本文研究了花药特异性酰基辅酶A合成酶（ACOS）、聚酮合成酶（PKS）和四酮吡喃酮还原酶（TKPR）催化的代谢步骤。使用脂肪酸作为起始底物，异源表达的烟草酶NtACOS 1、NtPKS 1和NtTKPR 1的连续活性导致产生还原的四酮-吡喃酮。转基因RNA干扰系，然后产生不同的烟草基因，被证明是必不可少的正常花粉发育和雄性育性。类似地，重组水稻OsPKS 1和OsTKPR 1显示出作为NtACOS 1的下游酶的功能。此外，这些水稻基因的插入突变株系表现出不同程度的花粉和种子形成受损。总之，还原四酮-吡喃酮似乎代表分类学上不同的植物物种中雄性育性所必需的常见孢粉素脂肪酰基前体。
The development of pollen wall with proper sporopollenin deposition is essential for pollen viability and male fertility in flowering plants. Sporopollenin is a complex biopolymer synthesized from fatty acid and phenolic derivatives. Recent investigations in Arabidopsis have identified a number of anther-specific genes involved in the production of fatty-acyl monomers potentially required for exine formation. The existence of ancient biochemical pathways for sporopollenin biosynthesis has been widely proposed but experimental evidence from plant species other than Arabidopsis is not extensively available. Here, we investigated the metabolic steps catalyzed by the anther-specific acyl-CoA synthetase (ACOS), polyketide synthase (PKS) and tetraketide -pyrone reductase (TKPR). Using fatty acids as starting substrates, sequential activities of heterologously expressed tobacco enzymes NtACOS1, NtPKS1 and NtTKPR1 resulted in the production of reduced tetraketide -pyrones. Transgenic RNA interference lines were then generated for the different tobacco genes which were demonstrated to be indispensable for normal pollen development and male fertility. Similarly, recombinant rice OsPKS1 and OsTKPR1 were shown to function as downstream enzymes of NtACOS1. In addition, insertion mutant lines for these rice genes displayed different levels of impaired pollen and seed formation. Taken together, reduced tetraketide -pyrones appear to represent common sporopollenin fatty-acyl precursors essential for male fertility in taxonomically distinct plant species.