1-Aminocyclopropane-1-carboxylic acid as a signalling molecule in plants

• Published in: AoB plants Vol. 5; p. plt017
• Main Authors: Yoon, Gyeong Mee, Kieber, Joseph J.
• Format: Journal Article Book Review
• Language: English
• Published: Oxford Oxford University Press 01.01.2013
• Subjects: 1-Aminocyclopropane-1-carboxylate synthase; Abscission; Biosynthesis; Carboxylic acids; Enzymes; Ethylene; Germination; Invited Reviews; Lethality; Methionine; Plant growth; Post-transcription; Ripening; Senescence; Signal transduction; SPECIAL ISSUE: Ethylene 2012; cell elongation; 1-Aminocyclopropane-1-carboxylic acid; LRR-RLKs; cell signalling; ACC synthase; cell wall; ethylene
• ISSN: 2041-2851; 2041-2851
• DOI: 10.1093/aobpla/plt017

This review summarizes and discusses the role of ACC synthase in plants. The classic role of ACC synthase is to act as the key enzyme in the biosynthetic pathway for the plant hormone ethylene. Several recent papers have converged on the notion that ACC, the immediate product of ACC synthase, acts as a novel signaling molecule in plants independent of its conversion to ethylene. The evidence for this hypothesis from these papers and potential roles for ACC is summarized and discussed. Abstract Ethylene influences many aspects of plant growth and development including germination, leaf and floral senescence and abscission, fruit ripening, and the response to abiotic and biotic stress. The pathways involved in the biosynthesis of and response to ethylene have been elucidated. The first committed and generally rate-limiting step in ethylene biosynthesis is the conversion of S-adenosyl-methionine to 1-aminocyclopropane-1-carboxylic acid (ACC) by ACC synthase (ACS). This enzyme is encoded by a gene family in most plants and is subject to both transcriptional and post-transcriptional control in response to numerous endogenous and environmental cues. In addition to its well-described function as the immediate precursor of ethylene, recent studies suggest an alternative, non-canonical role for ACC. These studies found that in some contexts, chemical inhibitors of ethylene biosynthesis caused effects on root cell expansion that were not observed when ethylene perception or signalling was disrupted, suggesting that ACC, but not ethylene, played a role in these specific processes. Furthermore, mutation of all eight ACS genes in Arabidopsis was found to result in embryo lethality, in contrast to the relatively modest developmental effects of null mutants in the ethylene signalling components. This divergence suggests that ACC may play a role as a signalling molecule in plants. Here, we first review the ethylene biosynthesis pathway and then discuss these studies suggesting an independent role of ACC as a signalling molecule.