Transcription Cofactor CsMBF1c Enhances Heat Tolerance of Cucumber and Interacts with Heat-Related Proteins CsNFYA1 and CsDREB2

Abstract

Multiprotein bridging factor 1 (MBF1) is a very important transcription factor (TF) in plants, whose members influence numerous defense responses. Our study found that MBF1c in Cucurbitaceae was highly conserved. <i>CsMBF1c</i> expression was induced by temperature, salt stress, and abscisic acid (ABA) in cucumber. Overexpressed CsMBF1c enhanced the heat resistance of a cucumber, and the <i>Csmbf1c</i> mutant showed decreased resistance to high temperatures (HTs). CsMBF1c played an important role in stabilizing the photosynthetic system of cucumber under HT, and its expression was significantly associated with heat-related TFs and genes related to protein processing in the endoplasmic reticulum (ER). Protein interaction showed that CsMBF1c interacted with dehydration-responsive element binding protein 2 (CsDREB2) and nuclear factor Y A1 (CsNFYA1). Overexpression of CsNFYA1 in <i>Arabidopsis</i> improved the heat resistance. Transcriptional activation of CsNFYA1 was elevated by CsMBF1c. Therefore, <i>CsMBF1c</i> plays an important regulatory role in cucumber's resistance to high temperatures.