The combination of transcriptomics and metabolomics uncovers mepiquat chloride improves the response of Litchi chinensis leaves to low-temperature stress in late spring

Abstract

Under low-temperature stress, the application of chemical regulation into litchi leaves remains largely uninvestigated especially during the late spring season. In this study, we came up with transcriptomics- and metabolomics-based strategies to comprehensively survey the response mechanisms of litchi to low temperature under the treatment of mepiquat chloride. After a big fraction of transcripts and metabolites were found differentially expressed, the pathway enrichment analysis showed that carbon metabolism accounted for a large number of DEGs (Differentially Expressed Genes). The effects of mepiquat chloride on carbon metabolism were found up regulated in the enrichment analysis for differential metabolites or transcripts. In addition, the combinational analysis of transcriptomics and metabolomics indicated mepiquat chloride coordinately regulates transcripts and metabolites by forming a tightly linked network. The integration of metabolomics and transcriptomics revealed that mepiquat chloride potentially promotes the expression of transcription factor and drives the upregulation of citrate synthase, and isocitrate dehydrogenase (NAD+) in the pathways of carbon metabolism. Meanwhile, upregulation of antioxidant related genes in the pathway of peroxisome. Considering that carbon metabolism is tightly related to photosynthesis, the physiological measurements of photosynthetic indexes suggested mepiquat chloride presented the potentials to improve the ability of photosynthesis for litchi under low-temperature stress. This comprehensive study combining transcriptomics and metabolomics provided a basis and strategy for understanding how higher plants respond stresses under chemical regulation.