In apple cultivation, dwarf rootstocks are chosen for dense planting and intensive cultivation, which is beneficial to production management. Dwarf rootstocks are widely used in apple production in China. However, the dwarfing mechanisms of dwarf interstock are still unclear. Here, M9 and SH40 were selected as the dwarf interstocks for potted Fuji apples. The key transcription factor MdWRKY24 was screened via transcriptional sequencing. The open reading frame sequence of the MdWRKY24 gene was 657 bp in length, encoded 218 amino acids, and was located on the cell membrane. The MdWRKY24-overexpressing Arabidopsis line showed a dwarf phenotype and delayed flowering. The DELLA protein RGA-like (RGL) gene is a repressor of the gibberellin signaling pathway. Yeast two-hybrid analysis revealed that MdWRKY24 could interact with MdRGL1/2/3. The results indicated that MdWRKY24 might affect plant dwarfing through the synergistic effect of MdRGL1/2/3. The MdWRKY24-MdRGL may be an important pathway underlying the gibberellin-mediated regulation of apple dwarfing.

Arbuscular mycorrhizae fungi (AMF) plays an important role in plants’ response to environmental stress, and the main environmental stress encountered in grape production is high temperature stress. This study aims to inoculate Funneliformis mosseae (A type of AMF) on grapes and investigate their tolerance to high temperature stress after inoculation. The results showed that AMF could infect grape roots, and the mycorrhizal infection rate was 20.78%. After inoculation with AMF, the growth of grape plants was significantly better than that in the non-inoculation group. Compared with the uninoculated group, the net photosynthetic rate, transpiration rate and stomatal conductance were higher in the AMF group, and the intercellular CO₂ concentration was lower. After high temperature treatment, there was no significant difference in the content of hydrogen peroxide (H₂O₂) in grape leaves between the two experimental groups at each time, and the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and other enzymes showed great differences, especially after high temperature treatment for 6 h. The activities of SOD, POD and CAT in AMF group were significantly higher than those in uninoculated group. The content of malondialdehyde (MDA) in grape leaves of the two experimental groups had no significant difference between 0 h and 3 h after high temperature treatment, and the MDA content in the AMF group was significantly lower than that in the uninoculated group after 6 h of high temperature treatment. The contents of soluble sugar and soluble protein in the AMF group were higher than those in the uninoculated group at all time periods, especially after 6 h of high temperature treatment. In addition, we found that VvHSP70, VvHSP17.9, VvGLOS1, VvHSFA2 genes all responded to high temperature stress, but there was no significant difference between the AMF group and the uninoculated group. It can be seen from the above that AMF can significantly enhance the adaptability of grape plants to high temperature stress by improving photosynthetic efficiency, antioxidant enzyme activity, soluble sugar and soluble protein content, and reduce Malondialdehyde (MDA) content, which provides guidance and theoretical basis for grape production.