An IDA peptide from Boea hygrometrica enhances desiccation tolerance but lacks activity in Arabidopsis

The IDA/IDL family expanded in eudicots, was retained in desiccation‑tolerant but lost in desiccation‑sensitive Gesneriaceae. BhIDA1 evolved unique sequence variations to activate desiccation tolerance in Boea hygrometrica but not in Arabidopsis. The inflorescence deficient in abscission (IDA) peptide family is known for its roles in organ abscission, senescence, and cell separation, yet whether IDA peptides contribute to desiccation tolerance (DT) is unknown. In this study, we identified eight IDA/IDL family members in the resurrection plant Boea hygrometrica, all harboring the conserved ePIPP domain. Phylogenetic analysis across 35 plant species revealed that the IDA/IDL family is absent in charophytes, bryophytes, lycophytes, gymnosperms, and basal angiosperms, appears sporadically in monocots, and underwent lineage‑specific expansion in basal eudicots and further expansion in core eudicots. Notably, IDA/IDL genes have undergone markedly loss in Gesneriaceae desiccation sensitive species. Compared with IDA homologs from other species, BhIDA1 harbors unique variations at positions 7 (T instead of S) and 12 (N instead of R/K) of the mature IDA peptide. Transcript abundance analysis showed that BhIDA1 was significantly induced by dehydration. Exogenous application of synthetic mBhIDA1 peptide and transient overexpression of BhIDA1-GFP both enhanced DT in B. hygrometrica, but had no detectable effect on drought survival in Arabidopsis thaliana. Our findings reveal the lineage‑specific expansion and contraction of the IDA/IDL family in angiosperms, and identify BhIDA1 as a positive regulator of DT in B. hygrometrica. This study provides the novel insights into peptide hormone-mediated DT in resurrection plants.