Submitted to: Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 5/23/2013
Publication Date: 7/9/2013
Citation: Sullivan, M.L., Green, H.A. 2013. Biosynthesis of hydroxycinnamoyl esters and amides in legume species [abstract]. Gordon Research Conference on Plant Metabolic Engineering, July 7-12, 2013, Waterville Valley, New Hampshire. Interpretive Summary:
Technical Abstract: In forage crops, protein that is degraded following harvest is poorly utilized by ruminant animals, resulting in both economic and environmental consequences. In red clover, secondary reactions of quinones resulting from polyphenol oxidase (PPO)-mediated oxidation of the caffeic acid derivatives phaselic acid (caffeoyl-malate) and clovamide (caffeoyl-L-DOPA amide) can prevent much of this protein breakdown. We have been working to transfer this natural system of protein protection to the important forage crop, alfalfa, which lacks both PPO and the required caffeic acid derivatives. We have identified a BAHD family hydroxycinnamoyl-CoA:malic acid transferase (HMT) and its corresponding gene from red clover that is responsible for phaselic acid accumulation. We have identified a similar HMT activity from common bean (Phaseolus vulgaris) that may favor production of phaselic acid over other hydroxycinnamoyl-malic acid esters. We have also detected a hydroxycinnamoyl-CoA:L-DOPA transferase (HDT) activity from red clover that is capable of synthesizing clovamide. Recently, we demonstrated that perennial peanut also has a PPO system, with caffeoyl-tartaric acid as one of the major PPO substrates. Leaves of perennial peanut contain a previously undescribed hydroxycinnamoyl-CoA:tartaric acid transferase (HTT) activity capable of making caffeoyl- and other hydroxycinnamoyl-tartaric acid derivatives. We are currently characterizing bean HMT, red clover HDT, and perennial peanut HTT activities and attempting to clone the corresponding genes. Characterization of these BAHD transferases and cloning their corresponding genes could lead to strategies to produce PPO substrates in alfalfa for protein protection, as well as providing insights into the structure/function relationships of this important class of enzymes.