Analysis of metabolites and pathways in cotton under salt and alkali stresses

Abstract

Elucidating the metabolic mechanism of plants under saline-alkali stress will help to further optimize breeding and cultivation, thereby increasing crop yields in saline-alkali soils. In this study, to analyze the differences in cotton metabolism under salt-alkali stress, liquid chromatography-mass spectrometry (LC-MS) was used to study the metabolites of cotton leaves under neutral salt and alkaline salt stress. The results showed that under salt stress, 7 and 2 types of sugars in cotton leaves were up-regulated in positive and negative ion modes, 3 types of amino acids were up-regulated, and 12 and 8 types of organic acids were up-regulated in cotton leaves under alkali stress. There are three kinds and five kinds of up-regulation in sugars, two kinds and nine kinds of up-regulation in organic acids, and two kinds of up-regulation in amino acids. 10 differential metabolic pathways were detected under salt stress. The most obvious metabolic pathway was linoleic acid metabolism, followed by starch and sucrose metabolism and arginine biosynthesis. Five differential metabolic pathways were found under alkaline stress. The most significant metabolic pathway was tryptophan metabolism, followed by arginine and proline metabolism and citric acid cycle (TCA cycle). Cotton adopts different metabolic mechanisms to resist salt-alkali stress. Salt stress tended to accumulate sugars and alkali stress tended to accumulate organic acids. In terms of energy metabolism, cotton starch and sucrose metabolism was more active under salt stress, and TCA cycle was more active under alkali stress. Salt stress improves the nitrogen assimilation ability of cotton, and alkali stress reduces the nitrogen assimilation ability.