Cucumbers, one of the world's most widely grown crops, face a significant challenge in regions with cold climates, particularly in winter cultivation within solar greenhouses. Cold stress negatively affects their growth, yield, and overall quality. While grafting onto cold-resistant rootstocks has proven effective in improving stress tolerance, the precise molecular mechanisms behind graft-induced cold tolerance remain elusive. Understanding how salicylic acid (SA) contributes to cold resistance could be the key to addressing this agricultural challenge.
Published (DOI: 10.1093/hr/uhae231) in Horticulture Research on August 9, 2024, this study, conducted by scientists from Shandong Agricultural University and Tai’an Academy of Agricultural Sciences, sheds light on the role of SA in enhancing cold tolerance in grafted cucumbers. By focusing on the interaction between CsNPR1 (non-expressor of pathogenesis-related gene 1, NPR1) and CsICE1 (inducer of CBF expression 1, ICE1), the research uncovers how SA signaling mediates cold stress responses in these crops.
The study reveals that grafted cucumber leaves accumulate more SA when exposed to cold stress, a process involving both synthesis within the leaves and transport from the rootstock. Researchers used RNA interference (RNAi) and overexpression techniques to target the phenylalanine ammonia-lyase (PAL) gene, essential for SA synthesis, confirming that higher SA levels are crucial for cold tolerance. Grafted plants with elevated SA content exhibited reduced electrolyte leakage, lower reactive oxygen species (ROS) accumulation, and enhanced expression of cold-responsive genes such as CsICE1 and CsDREB1A.
One of the most notable findings is the upregulation of CsNPR1, an important SA receptor, under cold conditions. The study demonstrates that CsNPR1 interacts with CsICE1 to trigger the activation of downstream cold resistance genes. This interaction was confirmed through advanced techniques including yeast two-hybrid, pull-down assays, and bimolecular fluorescence complementation, providing strong evidence of this key regulatory pathway. The research emphasizes the critical role of the PAL pathway in SA synthesis and transport between rootstock and scion, offering new possibilities for enhancing cold resistance in grafted cucumbers.
Dr. Huangai Bi, the lead researcher on the project, commented, “Our findings underscore the importance of SA in graft-induced cold tolerance in cucumbers. The interaction between CsNPR1 and CsICE1 is a critical regulatory mechanism that can be harnessed to improve crop resilience under cold stress.”
The implications of this research extend far beyond cucumbers. By leveraging the insights gained from this study, agricultural practices could be revolutionized, particularly in cold-prone regions. Understanding and manipulating the SA signaling pathway opens up opportunities for developing cold-tolerant cucumber varieties through genetic engineering and grafting techniques. This could lead to higher productivity and improved crop quality, contributing to more sustainable agricultural practices and enhanced food security in the face of climate challenges.
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References
DOI
10.1093/hr/uhae231
Original Source URL
https://doi.org/10.1093/hr/uhae231
Funding information
This work is funded by The National Science Foundation of China (31872155, 32372685), The National Key Research and Development Program of China (2019YFD1000300), The Special Fund of Vegetable Industrial Technology System of Shandong Province in China (SDAIT-05–10), and The Funds of Shandong ‘Double Tops’ Program (SYL2017YSTD06).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2022. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.