Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory for Biocontrol, Sun Yat-Sen University, Guangzhou, China.
Plant Biotechnol J. 2014 Oct;12(8):1132-42. doi: 10.1111/pbi.12222. Epub 2014 Jun 29.
Plant laccase (LAC) enzymes belong to the blue copper oxidase family and polymerize monolignols into lignin. Recent studies have established the involvement of microRNAs in this process; however, physiological functions and regulation of plant laccases remain poorly understood. Here, we show that a laccase gene, LAC4, regulated by a microRNA, miR397b, controls both lignin biosynthesis and seed yield in Arabidopsis. In transgenic plants, overexpression of miR397b (OXmiR397b) reduced lignin deposition. The secondary wall thickness of vessels and the fibres was reduced in the OXmiR397b line, and both syringyl and guaiacyl subunits are decreased, leading to weakening of vascular tissues. In contrast, overexpression of miR397b-resistant laccase mRNA results in an opposite phenotype. Plants overexpressing miR397b develop more than two inflorescence shoots and have an increased silique number and silique length, resulting in higher seed numbers. In addition, enlarged seeds and more seeds are formed in these miR397b overexpression plants. The study suggests that miR397-mediated development via regulating laccase genes might be a common mechanism in flowering plants and that the modulation of laccase by miR397 may be potential for engineering plant biomass production with less lignin.
植物漆酶（LAC）酶属于蓝色铜氧化酶家族，可将单体酚聚合为木质素。最近的研究已经确定了 microRNA 在此过程中的参与；然而，植物漆酶的生理功能和调节仍知之甚少。在这里，我们表明，一种受 microRNA miR397b 调控的漆酶基因 LAC4 控制拟南芥中木质素生物合成和种子产量。在转基因植物中，miR397b 的过表达（OXmiR397b）减少了木质素的沉积。OXmiR397b 系中小导管和纤维的次生壁厚度减小，且均减少了愈创木基和松柏基亚基，导致维管束变弱。相比之下，过表达 miR397b 抗性漆酶 mRNA 则表现出相反的表型。过表达 miR397b 的植物会发育出两个以上的花序，并增加了蒴果的数量和长度，从而增加了种子的数量。此外，这些过表达 miR397b 的植物会形成更大和更多的种子。该研究表明，miR397 通过调节漆酶基因介导的发育可能是开花植物的一种常见机制，而 miR397 对漆酶的调节可能是减少木质素生产植物生物量的潜在手段。
