The DREB2C.L-IAGLU module contributes to long-term heat stress via sugar metabolism in cucumber

Abstract

Cucumber is an important vegetable crop with thermophilic but heat-sensitive growth characteristics. Heat stress threatens cucumber growth and development, leading to a decline in both quality and yield. However, the evaluation system and molec- ular mechanism of long-term heat tolerance remain unclear. Here, an evaluation system in response to long-term heat stress was established, and chlorophyll a content and catalase(CAT) activity were identified as key evaluation indices for determining the heat tolerance of cucumber seedlings. Transcriptomic and physiological analyses revealed that sugar metabolism played a pivotal role in the heat response. Notably, the expression of CsIAGLU (Indoleacetic Acid glucosyltransferase) was significantly upregulated in heat-tolerant genotype PS76, whereas it was not induced in the heat-sensitive genotype PWRG. Loss of function of CsIAGLU by gene editing resulted in increased sensitivity to heat stress along with higher sugar contents, accelerated stomatal closure, and chlorophyll degradation. Furthermore, CsDREB2C.L, a positive regulator of heat stress response, directly bound to the CsIAGLU promoter to enhance its expression. Overexpression of CsDREB2C.L and CsIAGLU maintained stable sugar contents, thereby keeping stomatal opening and sustaining leaf greening to resist heat stress. Taken together, our findings provide valuable insights into the mechanism of heat resistance in cucumber.

Acknowledgements

This work was supported by the National Natural Science Foun-dation of China (32402569, 32025033, and 32372699), China Post-doctoral Science Foundation (2023M733805), the PhD Scientific Research and Innovation Foundation of Sanya Yazhou Bay Science and Technology City (HSPHDSRF-2023-05-013), and Pinduoduo-China Agricultural University Research Fund (PC2023B01002).

Authors contributions

J.Z., X.Z., M.X., Z.Z, and X.M. designed the research. X.M., C.L., and X.Z. performed the experiments. J.C. performed the gene edit-ing. X.Z., Y.H., Y.Y., Y.G., and Y.L. provided experimental assistance. X.Z., J.Z., and X.M. wrote the paper; all the authors revised the manuscript.

Data availability

The data that support the findings of this study are included in the manuscript or supplementary materials. The RNA-seq data have been deposited in the China National Center for Bioinformation National Genomics Data Center (https://ngdc.cncb.ac.cn/) under accession number CRA025585.

Conflicts of interest statement

The authors declare that they have no conflict of interest.

Supplementary material

Supplementary material is available at Horticulture Research online.

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