Melatonin and Indole-3-Acetic Acid Synergistically Regulate Plant Growth and Stress Resistance

Abstract

Plant growth and development exhibit plasticity, and plants can adapt to environmental changes and stress. Various phytohormones interact synergistically or antagonistically to regulate these responses. Melatonin and indole-3-acetic acid (IAA) are widespread across plant kingdom. Melatonin, an important member of the neuroendocrine immune regulatory network, can confer autoimmunity and protect against viral invasion. Melatonin functions as a plant growth regulator and biostimulant, with an important role in enhancing plant stress tolerance. IAA has a highly complex stress response mechanism, which participates in a series of stress induced physiological changes. This article reviews studies on the signaling pathways of melatonin and IAA, focusing on specific regulatory mechanisms. We discuss how these hormones coordinate plant growth and development and stress responses. Furthermore, the interactions between melatonin and IAA and their upstream and downstream transcriptional regulation are discussed from the perspective of modulating plant development and stress adaptation. The reviewed studies suggest that, at low concentrations, melatonin promotes IAA synthesis, whereas at high levels it reduces IAA levels. Similarly to IAA, melatonin promotes plant growth and development. IAA suppresses the melatonin induced inhibition of germination. IAA signaling plays an important role in plant growth and development, whereas melatonin signaling plays an important role in stress responses.

The role of indole derivative in the growth of plants: A review

“…IAA acts as a signal between rhizobium and plants. Experimental studies have demonstrated the application of Stenotrophomonas maltophilia Sg3, Proteus mirabilis BjB17, Providencia rettgeri AlDp5, Bacillus thuringiensis TNJbx.3.3 and Bacillus cereus GR12 , which are capable of synthesizing IAA, increased the number of pods of edamame beans ( Zhang et al., 2022 ). The secretion of root in Arabidopsis can trigger Falciphora oryza to produce IAA, thus promoting the development of the lateral root of Arabidopsis ( Sun et al., 2020 ).…”

“…However, endogenous JA-Trp plays a minor role in the regulation of plant growth ( Staswick et al., 2017 ). Additionally, Trp can be converted to melatonin by L-Trp decarboxylase (PSID) and tryptophan-5-hydroxylase (CYP71P1) ( Zhang et al., 2022 ). This conversion has been found to have an effect on plant growth, such as promoting root growth after germination ( Park and Back, 2012 ), influencing flowering time and regulating plant sugar metabolism ( Zhao et al., 2015 ; Lee et al., 2019 ).…”

“…Zhang et al. reviewed ( Zhang et al., 2022 ) that the first MT receptor in Arabidopsis was the candidate G protein-coupled receptor 2 (CAND2), a membrane protein that readily binds to MT ( Wei et al., 2018 ). Research has demonstrated that the introduction of melatonin from an external source can induce the upregulation of the genes RPOTm and RPOTmp through the CAND2 receptor and its G protein alpha subunit (GP A1) ( Bychkov et al., 2022 ).…”

“…The secretion of root in Arabidopsis can trigger Falciphora oryza to produce IAA, thus promoting the development of the lateral root of Arabidopsis (Sun et al, 2020). Gomes et al and Zhang et al (Gomes and Scortecci, 2021;Zhang et al, 2022) conducted reviews which revealed that IAA can modulate the transcription and expression of numerous genes through the ubiquitination complex, which is downstream of the repressor and activator of gene transcription factors. When there is a high growth hormone level in the cell, the ubiquitination complex is triggered by transport inhibitor response (TIR) proteins that are part of the growth hormone signaling pathway.…”

Promoting growth and morpho-physiological attributes in linseed (Linum usitatissimum L.) using indole acetic acid and gibberellic acid applied individually or jointly as foliar spray

“…Plant growth, development and differentiation are regulated by growth hormones either by inhibition or improvement in a variety of metabolic processes (Naeem et al, 2004). Of different plant hormones reported in the literature, indole acetic acid plays a critical role in cell division and elongation, as well as in several other physiological functions involved in plant growth and development (Aloni et al, 2006;Tian et al, 2014;Zhang et al, 2022). It is believed that it plays a significant role in the regulation of stress tolerance in plants subjected to various stressful cues.…”