SlWRKY80 -mediated jasmonic acid pathway positively regulates tomato resistance to saline-alkali stress by enhancing spermidine content and stabilizing Na⁺/K⁺ homeostasis

Abstract

Saline-alkali is an important abiotic stressor influencing tomato production. Exogenous methyl jasmonate (MeJA) is well known to increase tomato resistance to a variety of stresses, although its exact mechanism is yet unknown. In this study we confirmed that 22.5 μmol/l MeJA could significantly improve the saline-alkali stress resistance of tomato. Saline-alkali (300 mM) stress increased the endogenous MeJA and jasmonic acid (JA) contents of tomato by 18.8 and 13.4%, respectively. Exogenous application of 22.5 μmol/l MeJA increased the endogenous MeJA and JA contents in tomato by 15.2 and 15.9%, respectively. Furthermore, we found an important transcription factor, SlWRKY80, which responded to MeJA, and constructed its overexpressing and knockout lines through genetic transformation. It was found that SlWRKY80 actively regulated tomato resistance to saline-alkali stress, and the spraying of exogenous MeJA (22.5 μmol/l) reduced the sensitivity of SlWRKY80 knockout lines to saline-alkali stress. The SlWRKY80 protein directly combines with the promoter of SlSPDS2 and SlNHX4 to positively regulate the transcription of SlSPDS2 and SlNHX4, thereby promoting the synthesis of spermidine and Na⁺/K⁺ homeostasis, actively regulating saline-alkali stress. The augmentation of JA content led to a notable reduction of 70.6% in the expression of SlJAZ1, and the release of the SlWRKY80 protein interacting with SlJAZ1. In conclusion, we revealed the mechanism of exogenous MeJA in tomato stress resistance through multiple metabolic pathways, elucidated that exogenous MeJA further promotes spermidine synthesis and Na⁺/K⁺ homeostasis by activating the expression of SlWRKY80, which provides a new theoretical basis for the study of the JA stress resistance mechanism and the production of tomato.

Acknowledgements

Several funding sources were used to complete this work, including Shaanxi Province’s Scientific & Technological Innovative Research Team (2021TD-34) and the China Agriculture Research System (CARS-23-D06). We thank Professor Chuanyou Li and Lei Deng for providing spr8 and Professor Xiangqiang Zhan for providing the overexpression vector. We thank Jing Zhang for assistance in the MeJA and JA analysis, and Yangyang Yuan for helping in the use of a confocal laser scanning microscope. Anti-Flag was purchased from Sangon Biotech; anti-GST and anti-MBP antibodies were purchased from Abcam.

Author contributions

X.H., G.L., C.S., and X.L. conceived and designed the experiments. C.S., G.L., and X.H. wrote the paper. C.S. and X.L. performed the experiments. C.S., X.L., G.C., H.Z., and G.L. provided advice related to the research. Author A.K. provided great assistance in polishing the manuscript. All authors read and approved the manuscript for submission.

Data availability

The authors affirm that all the information required to substantiate the findings of the study is provided in both the paper and the supplementary materials, or can be acquired by contacting the corresponding author.

Conflict of interest

The authors declare no competing commercial or financial interest.

Supplementary data

Supplementary data is available at Horticulture Research online.

Accession numbers

A database of online sequence data was used to obtain sequence data (https://solgenomics.net/search/locus?tdsourcetag=spcqq_aiomsg).

The gene accession numbers used in this study can be found below: Solyc03g095770.2 (SlWRKY80), Solyc01g098190.3 (SINHX4), (SlSPDS2), Solyc07g042170.3 (SlJAZ1), Solyc12g009220.2 (SlJAZ2), Solyc03g122190.3 (SlJAZ3), Solyc12g049400.2 (SlJAZ4), Solyc03g118540.3 (SlJAZ5), Solyc01g005440.3 (SlJAZ6), Solyc11g011030.2 (SlJAZ7), Solyc06g068930.2 (SlJAZ8), Solyc08g036640.3 (SlJAZ9), Solyc08g036620.3 (SlJAZ10), Solyc08g036660.3 (SlJAZ11), Solyc01g009740.2 (SlJAZ12), Solyc01g103600.3 (SlJAZ13), Solyc03g122340.2 (SlLoxD), Solyc02g085730.2 (SlAOC).

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