Identification of the IDA peptide family in tomato and function of SlIDA8 in salt stress

Research on the flocculation-deficient abscission peptide IDA has mostly concentrated on how it controls the growth and development of plants. However, research on the role of defectin in tomato (Solanum lycopersicum) under salt stress remains limited.

Through analysis of the tomato genome, we identified a total of 11 SlIDA peptides and classified them into three categories based on their phylogenetic relationships. These genes exhibit chromosomal duplication events. Further structural analysis revealed that members of this gene family possess a high degree of evolutionary conservation. Expression analysis revealed that all 11 SlIDA genes are expressed in various tomato tissues, with their expression levels exhibiting significant changes in response to salt stress. Among them, SlIDA8 demonstrated the most pronounced upregulation, suggesting a potential key role in salt stress response. Functional validation demonstrated that the SlIDA8 protein localizes to both the cytoplasm and nucleus. Comparing the performance of SlIDA8-silenced plants with wild-type plants under salt stress revealed significantly reduced salt tolerance in the silenced plants. This result directly confirms that SlIDA8 is an important positive regulator in the tomato response to salt stress.

Results indicate that SlIDA8-silenced plants exhibit a more pronounced stress phenotype, characterized by accelerated chlorophyll degradation, increased membrane damage, reduced activity of reactive oxygen species scavenging enzymes, and elevated abscisic acid (ABA) content. This suggests that SlIDA8 silencing enhances tomato sensitivity to salt stress. These findings preliminarily elucidate the role of SlIDA8 as a positive regulator of salt stress in tomatoes providing a research basis for further investigation into IDA function.