Characterization and ectopic expression of a populus hydroxyacid hydroxycinnamoyltransferase

Area of Science:

• Plant biology
• Biochemistry
• Molecular genetics

Background:

• Cutin and suberin polyesters in plant cell walls are crucial barriers against environmental stresses.
• The physiological roles of aromatic components in these polyesters are not well understood, despite their known aliphatic constituents.

Purpose of the Study:

• To investigate the contribution of aromatic composition to the function of plant cutin and suberin polyesters.
• To identify and characterize enzymes involved in the incorporation of hydroxycinnamates into these polymers.

Main Methods:

• Functional screening of Populus trichocarpa BAHD/HXXXD acyltransferases.
• Ectopic expression of the identified hydroxycinnamoyltransferase (PtFHT1) in Arabidopsis.
• Analysis of ferulate and p-coumarate incorporation into cutin and suberin.
• Assessment of salt stress tolerance in transgenic plants.

Main Results:

• A novel hydroxycinnamoyltransferase, PtFHT1, was identified, specifically incorporating ferulate into plant polyesters.
• Ectopic expression of PtFHT1 increased ferulate levels in Arabidopsis cutin and suberin without altering aliphatic content.
• Transgenic plants overaccumulating ferulate exhibited significantly enhanced tolerance to salt stress, with improved seed germination and seedling establishment.

Conclusions:

• Aromatic compounds, particularly ferulate, are important minor components of plant lipidic polymers, contributing significantly to their sealing function.
• PtFHT1 plays a key role in modifying polyester composition and enhancing plant stress tolerance.