巴西橡胶树HbMYB52基因的克隆及其在拟南芥中的表达

Cloning of Hb MYB52 from Rubber Tree(Hevea brasiliensis) and Its Heterogenous Expression in Arabidopsis thaliana

为揭示Hb MYB52在巴西橡胶树(Hevea brasiliensis)木材发育过程中的功能,从其转录组中分离克隆到1个MYB转录因子G21亚组成员基因,命名为Hb MYB52,开放阅读框为726 bp,编码242个氨基酸的蛋白,在木质部中高度表达。在拟南芥(Arabidopsis thaliana)中过表达Hb MYB52,虽未改变转基因植株株型,但植株维管束间纤维细胞壁明显增厚,同时抑制了木质纤维、导管次生壁形成。转基因拟南芥株系3和株系6中纤维素和木质素含量减少,相应各组分合成的关键酶基因的表达量也不同程度下降;株系8产生了木质素异位沉积,且木质素合成关键酶基因表达活跃。因此,推测Hb MYB52参与了植物次生壁形成调控,在拟南芥次生壁形成中可能发挥了双重功能:一方面负调控维管束次生壁形成以及各组分的生物合成,另一方面具有促进束间纤维次生壁增厚的作用。

In order to reveal the function of MYB52 in wood development of Hevea brasiliensis, a G21 subgroup gene member of MYB transcription factor, named Hb MYB52, was cloned from its transcriptom. The ORF of Hb MYB5 was 2726 bp, encoding a protein with 242 amino acids. Hb MYB5 had high expression in xylem. Overexpression of Hb MYB52 in Arabidopsis thaliana had no significant difference in phenotype between transgenic and wild type plants, but it led to significant thickening of cell wall in interfascicular fiber, and inhibition of secondary wall formation in vessels and xylem fiber. The contents of lignin and cellulose decreased in transgenic lines 3 and 6, and the expressions of key enzyme genes involving the corresponding components biosynthesis were significantly descended in transgenic lines. However, the lignin deposition in transgenic line 8 was ectopic, and the expressions of genes related to lignin biosynthesis were active. Therefore, it was suggested that Hb MYB52 might play dual roles in the regulation of secondary wall formation, which negatively regulated secondary wall formation of vascular and promoted cell wall thickening of interfascicular fibers in A. thaliana.