| Our previous study found that the expression of the Haloxylon ammodendron 14-3-3 protein gene, HaFT-1, was affected by heat and drought stress, suggesting the involvement of HaFT-1 protein in the cross-talk between heat and drought stress signaling. Therefore, this study investigates the function of HaFT-1 in the cross-talk of heat and drought stress signals. Heat stress priming and secondary drought stress treatment were performed on H. ammodendron seedlings and it was found that heat stress priming promoted the expression of HaFT-1 under secondary drought stress. In addition, the function of HaFT-1 in the cross-talk between heat and drought stress cross-talk signaling was analyzed using the T3 generation homozygous line of HaFT-1 transgenic Arabidopsis thaliana. By measuring antioxidant enzyme activity, chlorophyll content, proline content, and malondialdehyde content, as well as staining with trypan blue, 4',6-diamidino-2-phenylindole (DAPI), diaminobenzidine (DAB) and nitrotetrazolium blue chloride (NBT), the intracellular physiological changes of HaFT-1 lines under heat and drought cross stress were analyzed. The expression of stress resistance related genes in HaFT-1 lines was analyzed by real-time fluorescence quantitative PCR (qRT-PCR). The results showed that after heat stress priming and subsequent secondary drought stress treatment, the survival rates of HaFT-1 lines seedlings and mature plants was significantly increased, while their cell death rate and ROS accumulation were significantly reduced. Meanwhile, the antioxidant enzyme activity and chlorophyll content of HaFT-1 lines mature plants, and the superoxide dismutase activity and chlorophyll content of HaFT-1 lines seedlings were significantly increased. qRT-PCR analysis showed that heat stress priming promoted the expression of genes related to photosynthesis, proline synthesis, antioxidant, drought stress response, and heat stress response pathways in the HaFT-1 lines. In summary, this study indicates that overexpression of HaFT-1 enhances the secondary drought stress tolerance of transgenic Arabidopsis after heat stress priming, suggesting that HaFT-1 is an important regulatory factor in the signal transduction of heat and drought cross stress. This study provides valuable insights into the molecular mechanisms underlying stress tolerance in H. ammodendron seedlings and offers references for the conservation of its germplasm resources. |