Abstract：Rosa hybrida boasts immense ornamental, edible and commercial value, but abiotic stress seriously affects its production efficiency. Strigolactones (SLs) are closely related to plant stress resistance, and exogenous application of the SLs analog GR24 (rac-GR24) can alleviate stress damage in roses, but the key gene information of endogenous signal transduction still needs to be enriched. In this study, the RhMAX2-like gene (GenBank No. PQ097003) was cloned by RT-PCR using the Rosa hybrida 'Carola' as the material. Bioinformatics was used to analyze its physiological and biochemical characteristics; qRT-PCR was used to analyze the expression patterns of RhMAX2-like gene in different tissues and under different conditions. The results showed that the RhMAX2-like gene had 2 202 bp nucleotides and encoded 733 amino acids, yielding a protein with a relative molecular mass of 81.633 kD and an isoelectric point of 5.29. RhMAX2-like harbored a typical F-box/LRR-repeat conserved domain and belonged to the F-box leucine-rich repeat protein family. Phylogenetic analysis revealed that RhMAX2-like clusters with MAX2 proteins. The protein interaction network indicated that RhMAX2-like interacted with proteins such as D14 within the SL signal transduction pathway. Examination of expression patterns across different tissues revealed that the RhMAX2-like gene was expressed in all tissues of R. hybrida, with the highest expression level observed in the roots. The expression of the RhMAX2-like gene was repressed by exogenous GR24 application, and the expression level exhibited a negative correlation with the GR24 treatment concentration, indicating that RhMAX2-like was subject to negative feedback regulation by exogenous GR24. Under 20% PEG6000 simulated drought and 200 mmol/L NaCl simulated salt stress, the expression of the RhMAX2-like gene was markedly upregulated. This study simulated the impact of exogenous application of 0.5 μmol/L GR24 on the phenotype and endogenous RhMAX2-like expression in R. hybrida under drought and salt stress conditions. The results indicated that 0.5 μmol/L GR24 could effectively ameliorate the phenotypic damage inflicted by drought and salt stress in R. hybrida. Over time, RhMAX2-like dynamically modulated its expression to maintain a balance between endogenous and exogenous SL levels. Thereby enhancing R. hybrida's resistance to salt and drought stress. In conclusion, this study elucidated the alleviating effects of GR24 on abiotic stress in R. hybrida, along with the expression dynamics of RhMAX2-like. The study provides theoretical support for further deciphering the strigolactone signal transduction pathway and to offer a novel candidate gene for the development of stress-resistant germplasm resources in rose under drought and salt stress conditions.
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