The transcription factor EIL1-MYB78 module negatively regulates cold tolerance in Actinidia chinensis.

Abstract

Kiwifruit has become an important horticultural crop widely planted in temperate and subtropical regions. However, most commercially cultivated kiwifruit, particularly those of Actinidia chinensis, are highly sensitive to cold stress. To overcome this industrial bottleneck, it is crucial to reveal the molecular mechanisms behind cold stress responses, ultimately providing new insights into the breeding of cold-tolerant kiwifruit varieties. Here, we found that EIL1 negatively regulates cold tolerance of A. chinensis by directly binding to the promoters of CBF1 and CBF2 to inhibit their expression. Besides, we found that EIL1 interacted and synergized with MYB78 to negatively regulate cold tolerance in A. chinensis. Further evidence suggested that the interaction between EIL1 and MYB78 enhanced the transcriptional repression activity of both proteins on CBF1 and CBF2. Therefore, we conclude that the EIL1-MYB78 module negatively regulates cold tolerance by directly inhibiting the expression of CBF1 and CBF2 genes in A. chinensis.