砀山酥梨果实F5H表达与石细胞发育的分析

Analysis of F5H Expression and Stone Cell Development in Pyrus bretschneideri cv. Dangshan Su Fruit

薄壁细胞次生壁木质化是石细胞形成的关键,石细胞团聚合主要受木质素单体组分及官能团含量的影响。阿魏酸5-羟化酶(F5H)是木质素合成途径中的一种关键酶,主要调控紫丁香基木质素(S木质素)单体的生物合成。本研究以砀山酥梨果实为材料,利用RT-PCR和RACE技术,得到砀山酥梨F5H全长c DNA,命名为Pb F5H(Gen Bank登录号为KC852907)。Pb F5H全长1 978 bp,其开放阅读框为1 551 bp,编码516个氨基酸,推测蛋白分子量是58.4 k Da,等电点为6.49。进化树分析表明,砀山酥梨F5H蛋白与其他物种具有很高同源性,与苹果的相似性达到96%。相关性分析表明,砀山酥梨木质素含量与石细胞含量和Pb F5H表达量高度正相关。且砀山酥梨Pb F5H参与调控梨果实S木质素单体的合成,影响木质素G/S比值。

The development of pear stone cells is closely related to the deposition of lignin on secondary cell walls, and the degree of stone cell polymerization is mainly determined by the lignin monomer composition and the content of functional groups. Ferulate 5-hydroxylase （FSH） is a key enzyme in lignin biosynthesis pathway that mainly regulates syringyl lignin. In this study, we cloned a F5H gene, named PbF5H （GenBank Accession No. KC852907） in Pyrus bretschneideri cv. Dangshan Su fruit by RT-PCR and RACE methods. The PbF5H cDNA comprises 1 978 bp, with an ORF of 1 551 bp, which encodes a putative protein containing 516 amino acid residues. The protein molecular weight is 58.4 kDa and the isoelectric point is 6.49. Phylogenetic analysis indicat- ed that PbFSH protein shared high homology with other plant FSHs, and showed 96% homology with Malus do- mestica. Correlation analysis showed that, lignin content had a highly positive correlation to stone cell content and PbF5H expression level. PbF5H as the key gene of syringyl lignin biosynthesis contributed to the G/S ratio.