trans-Cinnamic acid-induced leaf expansion involves an auxin-independent component

Area of Science:

• Plant biology
• Biochemistry
• Molecular genetics

Background:

• The phenylpropanoid pathway synthesizes diverse plant compounds, beginning with trans-cinnamic acid (t-CA).
• Cinnamate-4-hydroxylase (C4H) converts t-CA to p-coumaric acid.
• Previous studies indicated t-CA promotes Arabidopsis leaf growth via cell expansion, requiring auxin signaling.

Purpose of the Study:

• To provide further evidence that t-CA or its derivatives enhance leaf growth.
• To investigate the components of this growth response pathway.

Main Methods:

• Analysis of Arabidopsis mutants with altered C4H function.
• Application of exogenous t-CA.
• Assessment of leaf growth and cell expansion.

Main Results:

• Exogenous t-CA enhances leaf growth by increasing cell expansion.
• C4H loss-of-function mutants exhibit increased cell expansion.
• Leaf growth is enhanced by t-CA or upstream derivatives, independent of p-coumaric acid production.

Conclusions:

• Leaf growth enhancement by t-CA or its derivatives is confirmed.
• The growth response pathway involves auxin signaling.
• An additional, uncharacterized mechanism contributes to t-CA-mediated growth.