Potential Response Patterns of Endogenous Hormones in Cliff Species and under Salt Stress.

When plants are exposed to salt stress, endogenous hormones are essential for their responses through biosynthesis and signal transduction pathways. However, the roles of endogenous hormones in two cliff species ( and ( genus)) in the Taihang Mountains under salt stress have not been investigated to date. Following different time treatments under 500 mM salt concentrations, 239 differentially expressed gene (DEG)-related endogenous hormones were identified that exhibited four change trends, which in Profile 47 were upregulated in both species. The C-DEG genes of AUX, GA, JA, BR, ETH, and ABA endogenous hormones were significantly enriched in () and (). During the responsive process, mainly AUX, GA, and JA biosynthesis and signal transduction were triggered in the two species. Subsequently, crosstalk further influenced BR, EHT, ABA, and MAPK signal transduction pathways to improve the salt resistance of the two species. Within the protein-protein interactions (PPI), seven proteins exhibited the highest interactions, which primarily involved two downregulated genes ( and ) and eight upregulated genes (, , , , , , , and ) of the above pathways. The more upregulated expression of (in the ABA biosynthesis pathway), (in the GA signaling pathway), (in the ABA signaling pathway), and (in the ETH signaling pathway) in revealed that it had a relatively higher salt resistance than . This revealed that the responsive patterns to salt stress between the two species had both similarities and differences. The results of this investigation shed light on the potential adaptive mechanisms of and under cliff environments, while laying a foundation for the study of other cliff species in the Taihang Mountains.