Characterization of DnaJ gene family in Castanea mollissima and functional analysis of CmDnaJ27 under cold and heat stresses.

Background: The DnaJ gene family plays crucial roles in the plant abiotic stress response. Although the DnaJ gene family has been extensively characterized in various plants, its distribution in the Castanea mollissima genome is still unclear.

Results: In this study, 78 CmDnaJ genes were identified and characterized in the C. mollissima genome, divided into three subfamilies based on the phylogeny analysis. The abundance of cis-acting elements related to temperature stress in the promoter regions of the CmDnaJ genes suggested a close relationship between this family and temperature stress response. Dispersed duplication was identified as the main driving force behind the expansion of the CmDnaJ family. RNA-seq data from 192 runs across nine projects were analyzed, revealing the potential roles of CmDnaJ genes in the growth, development, and environmental stress response of C. mollissima. Weighted gene co-expression network analysis showed that CmDnaJ27 and CmDnaJ34 were located in the red module and significantly correlated with temperature stimulus-response. RT-qPCR experiments and subcellular localization validated the expression levels and specific locations of CmDnaJ genes under cold and heat stresses. Overexpression of CmDnaJ27 in Nicotiana tabacum significantly reduces its tolerance to cold and heat stresses.

Conclusions: This study provides insights into the important roles of the DnaJ gene family in C. mollissima growth, development, and response to environmental stress, and provides reference to the research of CmDnaJs in cold and heat stresses response.