Arginine and cysteine delay postharvest ripening of tomato fruit by regulating ethylene production

Ripe fruit, rich in essential nutrients, holds significant economic value. In this study, we investigate the dynamics of amino acids during the shelf-life of tomato fruit. To examine their influence on fruit ripening, we treat tomato fruit with either L-arginine (Arg) or L-cysteine (Cys). Our findings demonstrate that application of Arg or Cys retards fruit color change from green to red, and hinders the alterations in titratable acidity and soluble sugar content. Furthermore, Arg or Cys treatment suppresses the activities of key enzymes involved in ethylene biosynthesis, namely 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) and ACC oxidase (ACO), by downregulating the expression of SlACS2/4 and SlACO1 . This suppression further inhibits ripening-associated ethylene production. Overall, our study unveils that Arg and Cys treatments delay the ripening process of tomato fruit. The modulation of amino acid profile emerges as a significant factor in regulating fruit ripening and maintaining fruit quality during shelf-life.