title: MiR397b regulates both lignin content and seed number in Arabidopsis via modulating a laccase involved in lignin biosynthesis.
abstract: 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.
authors: Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory for Biocontrol, Sun Yat-Sen University, Guangzhou, China.
authors: Cong-Ying
authors: CY
authors: Wang
authors: Shengchun
authors: S
authors: Zhang
authors: Yang
authors: Y
authors: Yu
authors: Yu-Chun
authors: YC
authors: Luo
authors: Qing
authors: Q
authors: Liu
authors: Changliang
authors: C
authors: Ju
authors: Yu-Chan
authors: YC
authors: Zhang
authors: Liang-Hu
authors: LH
authors: Qu
authors: William J
authors: WJ
authors: Lucas
authors: Xiaojing
authors: X
authors: Wang
authors: Yue-Qin
authors: YQ
authors: Chen
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D042845:Laccase / Q000235:genetics* / Q000378:metabolism; D008031:Lignin / Q000032:analysis / Q000096:biosynthesis*; D018519:Meristem / Q000235:genetics / Q000254:growth & development; D035683:MicroRNAs / Q000235:genetics*; D010641:Phenotype; D018520:Plant Shoots / Q000235:genetics / Q000254:growth & development; D058526:Plant Vascular Bundle / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified; D012639:Seeds / Q000235:genetics / Q000254:growth & development
chemical_list: D029681:Arabidopsis Proteins; C584086:MIRN390 microRNA, Arabidopsis; D035683:MicroRNAs; D008031:Lignin; C000598372:LAC4 protein, Arabidopsis; D042845:Laccase
keywords: Arabidopsis thaliana; laccase; lignin; miR397; seed yield; silique