The correlation analysis between phytohormones and metabolites provides new insights for salinity studies
Hormones association with fatty acids may favour the protein lipid modifications such as S-acylation and N-myristoylation, which correspond to the irreversible link of lipid (fatty acid) to the N-terminal amino acid residue of proteins. The lipid modification could be involved in regulation of several biological processes redox homeostasis, protein-membrane associations and protein stability under various environmental stresses (Boyle et al., 2016; Majeran et al., 2018). The exogenous application of MeJA on shoots of soybean showed increased accumulation of cell wall SFAs to maintain growth under drought stress (Mohamed & Latif, 2017). Further, JA also showed strong interaction with organic acids and amino acids with the salinity treatment time suggesting that organic acids and amino acids may be involved in promoting salt-induced growth by regulating osmotic balance, ion homeostasis, carbon and nitrogen balance under salt stress (Sharma et al., 2018; Siddiqi & Husen, 2019). The results suggest that the increased interaction between hormones and metabolites may be beneficial for Pongamia to survive under extreme salinity stress (Sahoo et al., 2014; Formentin et al., 2018).
The number of interactions between hormones and metabolites increased with increasing treatment time in roots of 300 mM NaCl treated plants. In contrast, the number interactions were decreased with the treatment time in roots of 500 mM NaCl treated plants. The high correlation between hormones and cell-wall carbohydrates and organic acids may enhance the water permeability as well as pH regulation under salt tress conditions (Marriboina et al., 2017; Marriboina & Attipalli, 2020a). The increased association of hormones with organic acids may provide immediate source of carbon energy and osmotic balance under salinity stress conditions (Assaha et al., 2017; Böhm et al., 2018; Yang & Guo, 2018).