Genome-Wide Identification and Functional Investigation of 1-Aminocyclopropane-1-carboxylic Acid Oxidase (ACO) Genes in Cotton

Abstract

ACO is one of the rate-limiting enzymes in the biosynthesis of ethylene, and it plays a critical role in the regulation of plant growth and development. However, the function of ACO genes in cotton is not well studied. In this study, a total of 332 GhACOs, 187 GaACOs, and 181 GrACOs were identified in G. hirsutum, G. arboretum, and G. raimondii, respectively. Gene duplication analysis showed that whole-genome duplication (WGD) and tandem duplication were the major forces driving the generation of cotton ACO genes. In the promoters of GhACOs, there were cis-acting elements responding to stress, phytohormones, light, and circadian factors, indicating the possible involvement of GhACOs in these processes. Expression and co-expression analyses illustrated that most GhACOs were not only widely expressed in various tissues but also coexpressed with other genes in response to salt and drought stress. GhACO106_At overexpression in Arabidopsis promoted flowering and increased salt tolerance. These results provide a comprehensive overview of the ACO genes of cotton and lay the foundation for subsequent functional studies of these genes.

The Ethylene Biosynthetic Enzymes, 1-Aminocyclopropane-1-Carboxylate (ACC) Synthase (ACS) and ACC Oxidase (ACO): The Less Explored Players in Abiotic Stress Tolerance

“…Genome-wide analysis of Gossypium species documented that GhACS10.2 showed high expression at the early stage of heat stress; also, GhACS12.2 responded to heat but GhACS12.1 did not change under stress [116]. Upstream sequence analysis of GhACOs showed heat stress response elements (STREs) in cis-acting elements of these genes, confirming their role in heat stress [144]. In Triticum, under heat stress, the expression of TaACS6 and TaACS8 was increased consistently after 2 h of treatment; however, TaACS3 and TaACS10 were upregulated only after 24 h of treatment [49].…”

“…As a result, these mutants displayed enhanced leaf biomass and experienced delayed activation of ethyleneresponsive genes, with no significant variations in Cd levels between the wild-type and mutant plants [110]. A recent study found metal response element (AP-1 and O2-site) cis-acting elements in ACO genes of Gossypium, implying its role in metal stress [144]. Khan and Khan [155] reported that under Ni and Zn toxicity, ACS activity and ethylene evolution increase; however, ethephon (ethylene donor) application under stress was found to reduce the ACS activity and bring ethylene production to the optimum level, thus enhancing antioxidant machinery and improving the PSII (photosystem II) efficiency, N-use efficiency, and photosynthesis in mustard plants.…”

“…A genome-wide study on cotton species showed that most of the GhACS6 responded to drought stress at the early stage, whereas the expression of GhACS6.1, GhACS10.2, and GhACS12.1 did not change [116]. In addition, at upstream sequences of the promoter of GhACOs, various drought response elements, like DRE core, DRE1, MYC, MBS, and MYB recognition sites, are observed, indicating its role in drought stress [144]. Furthermore, wheat genome-wide analysis showed that the expression of TaACS3/6/10 was upregulated, and among them, TaACS3/10 was induced within 1 h after treatment, while the expression of TaACS8 was downregulated [49].…”

MaDREB1F confers cold and drought stress resistance through common regulation of hormone synthesis and protectant metabolite contents in banana

“…ACO is a rate-limiting enzyme for ethylene biosynthesis [ 54 ]. Accompanied by an increase in ethylene production under cold and drought conditions, expression of ACO s significantly increased in various plant species [ 47 , 55 – 59 ]. We found that MaDREB1F can directly bind to and activate the promoter of MaACO20 under cold and drought treatment.…”

Modification of Xyloglucan Metabolism during a Decrease in Cell Wall Extensibility in 1-Aminocyclopropane-1-Carboxylic Acid-Treated Azuki Bean Epicotyls

“…The inhibition of elongation growth and promotion of lateral expansion of stems have been recognized as principal ethylene effects in plants. 1-Aminocyclopropane-1-carboxylic acid (ACC) is the immediate precursor of ethylene [ 2 ]. The production of ethylene induces ethylene responses such as the inhibition of elongation growth and promotion of lateral expansion of stems, when seedlings are treated with ACC.…”