Integrated Transcriptome and Metabolome Analysis of Salinity Tolerance in Chrysanthemum Polyploids
Polyploidization is a common phenomenon in plants, and autopolyploids often exhibit gigantism and enhanced salt tolerance. There are many reports on the molecular mechanisms of autopolyploid salt tolerance. However, it's unclear if the salt - tolerance molecular mechanisms of autopolyploids in the same genus are consistent. In this study, diploid and autotetraploid tetraploid Chrysanthemum lavandulifolium and tetraploid and autopolyploid octaploid Gongju were selected as the study materials. Varying NaCl treatment times were set to observe morphology and measure antioxidant enzyme activities. Results indicated autopolyploids wilted less than their parents under salt stress. Also, these autopolyploids had higher antioxidant - enzyme activities than their parental counterparts. Through transcriptome and metabolome analysis, we found that tetraploid C. lavandulifolium showed significant enrichment of differentially expressed genes and metabolites in glycerophospholipid metabolism, phenylalanine metabolism, and flavonoid/flavonol biosynthesis pathways compared to diploid C. lavandulifolium. In contrast, between tetraploid and octoploid Gongju, differentially expressed genes and metabolites were mainly enriched in terpenoid backbone biosynthesis, purine metabolism, and ABC transporter-related pathways. At the level of hormone regulation, the octoploid Gongju significantly upregulated the metabolic synthesis of abscisic acid (ABA) and jasmonic acid (JA), as well as the expression of downstream salt-tolerance-related genes, compared with the tetraploid. In contrast, the tetraploid C. lavandulifolium significantly upregulated ABA biosynthesis and the expression of downstream salt-tolerance-related genes compared with the diploid. This reveals the differentiation in salt tolerance regulatory networks among autopolyploids of the genus Chrysanthemum.