Molecular characteristics of CML genes in Chinese jujube and their expression patterns in resistance to cold stress

  Objective  This paper aims to investigate the important founction of CaM-like proteins in Chinese jujube in resistance to cold stress and identify the key ZjCML, which could provide theoretical basis for cold breeding in Chinese jujube by using them.

  Method  Through using bioinformatics technology, the number and related structural information of CML in Chinese jujube were analyzed comprehensively in the current study. And then, we used RNA-seq and real-time fluorescence quantitative PCR technology to analyze its expression pattern in response to low temperature stress, laying a foundation for screening key cold resistance genes.

  Result  A total of 23 ZjCML genes were identified in Chinese jujube genome. All of them distributed unevenly on 12 chromosomes. In addition, ZjCML can be divided into 12 subgroups, and protein interaction network prediction showed that 16 ZjCML existed in the network and they had mutual interaction relationships. Moreover, RNA-seq analysis showed that the expression patterns of ZjCML13 and ZjCML6 in response to cold stress between ‘Dongzao’ and its autotetraploids were significantly different. The expression level of ZjCML13 in response to cold stress in ‘Dongzao’ was significantly higher than that in its autotetraploid at 6 and 24 h. External CaCl₂ and melatonin treatments could significantly induce the expression of ZjCML13 in autotetraploids ‘Dongzao’ under cold stress at 6 and 24 h, indicating that it may regulate cold resistance of autotetraploid ‘Dongzao’ by inducing the expression of ZjCML13.

  Conclusion  The ZjCML gene family have specific characteristics and expression patterns, ZjCML13 might play important role in regulation of cold difference between ‘Dongzao’ and its autotetraploids.