Transcriptome Analysis on the Underlying Physiological Mechanism of Calcium and Magnesium Resolving “Sugar Receding” in ‘Feizixiao’ Litchi Pulp

The sugar contents of ‘Feizixiao’ litchi (Litchi chinensis Sonn.) decrease at full maturity; calcium (Ca) and magnesium (Mg) foliar fertilizer can resolve this “sugar receding”. To investigate the physiological mechanism Ca Mg used to receding” phenomenon in pulp, 16-year-old trees were treated with 0.3% CaCl2 + MgCl2 spraying or water as a control. We determined pulp content over two-year period 2020 2021. Pulp total RNA was extracted for transcriptome sequencing 2020, expression pattern 10 differentially expressed genes (DEGs) verified by real-time PCR results showed that treatment significantly increased fructose soluble maturity both years. According Gene Ontology (GO) functional enrichment analysis, there 155 DEGs divided into 35 GO categories, among which 49 pathways according Kyoto Encyclopedia Genes Genomes (KEGG) pathway analysis. isolated sugar-metabolism-related enzyme genes, including sucrose synthase (SS), acid invertase (AI), neutral (NI), phosphate (SPS), hexokinase (HK). All sucrose-metabolism-related (NI, AI, SS, SPS) downregulated, six seven HK downregulated. patterns PCR, significant linear relationships (r2020 = 0.9127, r2021 0.8705). In conclusion, inhibited synthesis phosphorylation hexose downregulating SPS, thus increasing litchi.