Comparative transcriptome profiling reveals the cold stress responsiveness in two contrasting Chinese jujube cultivars
Abstract Background Low temperature is a major factor influences the growth and development of Chinese jujube ( Ziziphus jujuba Mill.) in cold winter and spring. Little is known about the molecular mechanisms for coping with different freezing stress conditions in jujube. To gain insight into the freezing-related molecular changes, we conducted comparative transcriptome analyses from the cold-sensitive cultivar ‘Dongzao’ and cold-tolerant cultivar ‘Jinsixiaozao’ using RNA-Seq. Results In our study, more than 20,000 genes were detected at chilling (4°C) and freezing (-10°C, -20°C, -30°C and -40°C) stress between two cultivars. The numbers of differentially expressed genes (DEGs) between the two cultivars was 1831, 2030, 1993, 1845 and 2137 under the five treatments, respectively. Functional enrichment analysis suggested that metabolic pathway, response to stimulus and catalytic activity were significantly enriched at stronger freezing stress. Among them, nine DEGs participated in the pathway of Ca 2+ signal, thirty-two DEGs were identified to take part in sucrose metabolism, and other DEGs were identified to participate in the regulation of ROS, plant hormones and antifreeze protein. In addition, important transcription factors ( WRKY , AP2 / ERF , NAC and bZIP ) participating in the freezing stress were activated under different degrees of freezing stress. Conclusions Our research provides a more comprehensive understanding of DEGs involved in freezing stress at the transcriptome levels in Z. jujuba , especially two cultivars with different cold tolerance. These results expanding our understanding on the complex molecular mechanism of jujube, which also provide new insights and candidate genes for genetic improvement of jujube tolerance to freezing stress.