Cloning of HbMYB52 from Rubber Tree (Hevea brasiliensis) and Its Heterogenous Expression in Arabidopsis thaliana

Abstract:

In order to reveal the function of MYB52 in wood development of Hevea brasiliensis, a G21 subgroup gene member of MYB transcription factor, named HbMYB52, was cloned from its transcriptom. The ORF of HbMYB5 was 2726 bp, encoding a protein with 242 amino acids. HbMYB5 had high expression in xylem. Overexpression of HbMYB52 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 HbMYB52 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.