Cloning and characterization of a CCoAOMT gene involved in rapid lignification of endocarp in dove tree (Davidia involucrata Baill.)

Abstract

The long period of seed dormancy is one of the most important reasons leading to the low fertility of dove tree (Davidia involucrata Baill., Davidia hereinafter). During the fruit development process of Davidia, the endocarps will become particularly compact and hard, which was considered as a critical reason for the long seed dormancy of Davidia. However, the biological significance and regulatory mechanism of this process remain unclear. In this study, we identified a CCoAOMT gene, a key member of the lignin biosynthesis pathway, from Davidia endocarp. The gene named DiCCoAOMT1 has an ORF (open reading frame) of 744 bp and encodes a predicted protein of 239 amino acids. The expression of DiCCoAOMT1 is endocarp-specific and the expression levels increased along with the fruit development process. The encoding protein of DiCCoAOMT1 demonstrated a relatively high O-methyltransferase activity when using caffeic acid as a substrate in vitro. The tissue-specific CCoAOMT gene identified in this study might play a key role in specifically regulating the rapid lignification process in Davidia endocarp.

Keywords

• Seed dormancy
• endocarp
• lignification
• CCoAOMT (caffeoyl-CoA O-methyltransferase)
• dove tree (Davidia involucrata Baill.)