Transcriptome Analysis to Elucidate the Enhanced Cold Resistance of Phoebe zhennan Pretreated with Exogenous Calcium

Phoebe zhennan is a high-quality timber tree species, and cold stress is one of the most remarkable abiotic factors limiting its growth and development. In this study, effects of exogenous CaCl2 on cold resistance of P. Zhennan were surveyed. CaCl2pretreatment increased the levels of abscisic acid, peroxidase, catalase, proline, and soluble sugar, while decreased the levels of malondialdehyde and relative electrical conductivity. In addition, RNA-sequencing was used to investigate global transcriptome responses to cold stress. A total of 4245 differentially expressed genes were identified, including 477 up-regulated and 3768 down-regulated. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated that these DEGs were associated to the plant-pathogen interaction pathway, in which calcium-dependent protein kinase (CDPK) play key role for improving the cold resistance of P. zhennan. Our results can be useful to understand the Ca2+-mediated cold resistance mechanism for improving cold stress tolerance in P. Zhennan seedlings.