Fu Xin, Feng Yiqing, Zhang Yanyan, Bi Huangai, Ai Xizhen
Key Laboratory of Crop Biology and Genetic Improvement of Horticultural Crops in Huanghuai Region, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, Shandong 271018, China.
Institute of Peanut, Tai'an Academy of Agricultural Sciences, Tai'an, Shandong 271000, China.
Hortic Res. 2024 Aug 9;11(10):uhae231. doi: 10.1093/hr/uhae231. eCollection 2024 Oct.
Salicylic acid (SA) plays a role in the regulation of grafting-induced cold tolerance. However, the molecular mechanism behind it is still unknown. Here, we established that the phenylalanine ammonia-lyase (PAL) pathway-dependent elevate in SA content in grafted cucumber leaves was not only synthesized in the leaves but also transported from the roots under chilling stress. RNAi- with low SA content as rootstock reduced SA accumulation in grafted seedling leaves while decreasing rootstock-induced cold tolerance, as evidenced by higher electrolyte leakage (EL), hydrogen peroxide (HO), and superoxide anion (O ) contents and lower expression of cold-responsive genes (, Cs, , and ), whereas OE- with high SA content as rootstock improved the cold tolerance of grafted plants in comparison with the wild type (WT). In addition, was significantly upregulated in grafted cucumber under chilling stress, with exogenous and endogenous overexpressed SA inducing its transcriptional expression and protein stability, which exhibited higher expression in grafted plants than in self-root plants. While -overexpression (-) seedlings as scions were more tolerant to chilling stress than WT seedlings, -suppression (-) seedlings as scions were more vulnerable to chilling stress. Notably, CsNPR1-CsICE1 interactions alleviated ROS accumulation and activated the expression of and to enhance SA-mediated chilling tolerance in grafted cucumber. Overall, our findings reveal that SA enhances chilling tolerance in grafted cucumbers via the model of the CsNPR1-CsICE1 transcriptional regulatory cascade.
水杨酸（SA）在嫁接诱导的耐寒性调节中发挥作用。然而，其背后的分子机制仍不清楚。在此，我们确定，嫁接黄瓜叶片中依赖苯丙氨酸解氨酶（PAL）途径的SA含量升高不仅在叶片中合成，而且在低温胁迫下从根部运输而来。以低SA含量的RNAi为砧木降低了嫁接幼苗叶片中的SA积累，同时降低了砧木诱导的耐寒性，较高的电解质渗漏（EL）、过氧化氢（HO）和超氧阴离子（O）含量以及低温响应基因（、Cs、、和）的较低表达证明了这一点，而以高SA含量的OE为砧木与野生型（WT）相比提高了嫁接植物的耐寒性。此外，在低温胁迫下嫁接黄瓜中显著上调，外源和内源过表达的SA诱导其转录表达和蛋白质稳定性，其在嫁接植物中的表达高于自根植物。虽然作为接穗的-过表达（-）幼苗比WT幼苗更耐低温胁迫，但作为接穗的-抑制（-）幼苗更容易受到低温胁迫。值得注意的是，CsNPR1-CsICE1相互作用减轻了ROS积累并激活了和的表达，以增强嫁接黄瓜中SA介导的耐寒性。总体而言，我们的研究结果表明，SA通过CsNPR1-CsICE1转录调节级联模型增强了嫁接黄瓜的耐寒性。
