Key role of hormone signal transduction and lipid metabolism in the development of Nitraria sibirica leaves: An integrated metabolomic and transcriptomic analysis

Abstract

Plant growth is a complex process controlled by a variety of genetic and environmental variables. Nitraria sibirica Pall. is a multi-purpose euhalophyte with economic and medicinal value. However, the molecular mechanisms underlying the changes at different growth stages in N. sibirica remain unreported. In this study, the morphology and physiological characteristics of N. sibirica were compared at the vegetative, full flowering, and fruiting stages. Metabolomics and transcriptomics were used to describe metabolite accumulation and transcriptome expression at different stages, and the relationship between gene expression patterns and metabolite accumulation was studied based on a joint analysis of the two approaches. The results indicated significant variations in the morphological and physiological characteristics of N. sibirica at different growth stages (P < 0.05). Transcriptome and metabolome samples corresponding to the three stages were clearly distinguished, and the metabolite and gene module showed high consistency. The amount of DEMs and DEGs decreased as leaf growth progressed. Differentially expressed genes (DEGs) predominantly belonged to the MYB transcription family, whereas differentially expressed metabolites (DEMs) were dominated by lipids and lipid-like molecules. DEGs were mainly enriched in plant hormone signal transduction, cutin, suberine, and wax biosynthesis pathways, whereas DEMs were mainly enriched in linoleic acid, alpha-linolenic acid metabolism, and phenylpropane biosynthesis pathways. Combined transcriptomic and metabolomic analyses revealed that plant hormone signal transduction, linoleic acid, alpha-linolenic acid, cutin, suberine, and wax biosynthesis were the most significant key pathways for the co-enrichment of DEMs and DEGs. Pearson correlation analysis showed that physiological traits were strongly correlated with DEGs, whereas morphological traits were strongly correlated with DEMs. Moreover, a strong correlation was also observed between DEMs and DEGs. In conclusion, this research provides insights into the metabolic and transcriptional regulatory networks involved in plant development.