RrWRKY1, a Transcription Factor, Is Involved in the Regulation of the Salt Stress Response in Rosa rugosa

Salt stress has become a major environmental problem affecting plant growth and development. Some WRKY transcription factors have been reported to be involved in the salt stress response in plants. However, there are few studies on the involvement of WRKYs in the salt stress response in Rosa rugosa. In this study, we isolated a salt tolerance gene, RrWRKY1, from R. rugosa. RrWRKY1 was found to belong to Group I of the WRKY family, and it was specifically expressed in leaves and petals. RrWRKY1 expression was upregulated under NaCl stress in rose leaves. After silencing RrWRKY1 in R. rugosa, transgenic plants showed dry leaves and black and brown veins, indicating sensitivity to salt stress. At the same time, the transcription levels of the salt tolerance-related genes RrNHX1, RrABF2, RrRD22, RrNCED1, and RrHKT1 also changed significantly. The superoxide dismutase (SOD) and peroxidase (POD) activities decreased, the proline content decreased, and the malondialdehyde (MDA) content in the gene-silenced plants increased, indicating that RrWRKY1 regulates the salt tolerance of R. rugosa. In addition, the overexpression of RrWRKY1 in Arabidopsis thaliana improved the germination rate and the average of the main root and lateral root lengths, and the transgenic plants had a larger number of lateral roots than the WT plants under salt stress. This study provides candidate gene resources for salinity tolerance breeding and a theoretical basis for analyzing the salinity tolerance mechanism of the WRKY gene.