山楂中木质素合成调控转录因子MYB46的克隆及功能鉴定  

Cloning and Functional Identification of a Lignin Regulation Transcription Factor MYB46 in Hawthorn

作　　者：陈可钦 雷莹莹 郭运娜 宋梦如 刘丽馥 代红艳[1] CHEN Ke-qin;LEI Ying-ying;GUO Yun-na;SONG Meng-ru;LIU Li-fu;DAI Hong-yan(College of Horticulture,Shenyang Agricultural University,Shenyang 110161,China)

机构地区：[1]沈阳农业大学园艺学院,沈阳110161

出　　处：《沈阳农业大学学报》2020年第4期395-401,共7页Journal of Shenyang Agricultural University

基　　金：国家自然科学基金项目(31972380,31170635)。

摘　　要：模式植物拟南芥AtMYB46在次生壁形成过程中充当纤维素、木质素和木聚糖生物合成基因的转录调节因子,其表达受植物特异性转录因子NAC家族成员的调控。然而,果树次生壁生物合成的调节机制在很大程度上尚不清楚。从山楂(Crataegus pinnatifida)中分离克隆得到与拟南芥和苹果中MYB46具有高度保守R2R3 MYB DNA结合结构域的MYB46编码基因,并将其命名为CpMYB46。通过农杆菌介导的转化方法分别在拟南芥、烟草和苹果中异位表达CpMYB46基因。异位表达CpMYB46基因的拟南芥和烟草的次生壁过量沉积而导致生长受到限制,表现出株型矮小和叶片上卷的表型。定量RT-PCR数据表明,CpMYB46基因可以调控转基因植株次生细胞壁生物合成中下游基因的表达,茎切片观察表明异位表达CpMYB46明显增加了转基因拟南芥、烟草和苹果木质部中次生壁厚度。EMSA实验结果表明其上游NAC家族成员CpSND1可以直接结合CpMYB46基因的启动子。研究揭示了CpMYB46在DNA结合结构域与拟南芥和苹果中的MYB46具有高度保守性,而且在植物次生壁合成调控中也存在功能保守性。研究为揭示山楂内种皮中木质素的合成提供了分子依据,也为山楂的分子育种奠定了基础。In Arabidopsis thaliana,AtMYB46 has been reported to act as a transcriptional regulator of cellulose,lignin and xylan biosynthesis in the secondary wall formation process,which is regulated by members of the plant-specific transcription factor NAC family.However,in fruit trees,the regulation mechanism of secondary wall biosynthesis is largely unclear.In this study,the MYB46 gene was isolated from Crataegus pinnatifida,and because its encoding protein has a highly conserved R2R3 MYB DNA binding domain compared with Arabidopsis AtMYB46 and apple MdMYB46,it was named CpMYB46.The CpMYB46 gene was then ectopically expressed in Arabidopsis,tobacco and apple by Agrobacterium-mediated transformation methods.The growth of CpMYB46-expressed ectopically Arabidopsis and tobacco was restricted due to excessive deposition of secondary walls,including inhibited growth,upward-curling leaves,.Quantitative RT-PCR data indicated that CpMYB46 gene could regulate the expressions of downstream genes in secondary cell wall biosynthesis of transgenic plants.Microscopic observation of stem transversal section showed that ectopic expressing CpMYB46 increased the thickness of secondary wall in transgenic Arabidopsis,tobacco and apple.EMSA experiments showed that CpSND1 can directly bind to the promoter of CpMYB46.This study revealed that CpMYB46 is highly conserved in the DNA-binding domain with MYB46 in Arabidopsis and apples,and has functional conservation in the regulation of plant secondary wall synthesis.This study provides the molecular basis for the synthesis of lignin in hawthorn,and lays a foundation for the molecular breeding of the hawthorn.

关 键 词：木质素 山楂 转录因子 MYB46 SND1 转录调控 次生细胞壁 

分 类 号：Q782[生物学—分子生物学]