As one of the most prominent gene families, R2R3-MYB transcription factors significantly regulate biochemical and physiological processes under salt stress. However, in Sophora alopecuroides, a perennial herb known for its exceptional saline alkali resistance, the comprehensive identification and characterization of SaR2R3-MYB genes and their potential functions in response to salt stress have yet to be determined. We investigated the expression profiles and biological functions of SaR2R3-MYB transcription factors in response to salt stress, utilizing a transcriptome-wide mining method. Our analysis identified 28 SaR2R3-MYB transcription factors, all sharing a highly conserved R2R3 domain, which were further divided into 28 subgroups through phylogenetic analysis. Some SaR2R3-MYB transcription factors showed induction under salt stress, with SaR2R3-MYB15 emerging as a potential regulator based on analysis of the protein–protein interaction network. Validation revealed the transcriptional activity and nuclear localization of SaR2R3-MYB15. Remarkably, overexpression of SaR2R3-MYB15 in transgenic plants could increase the activity of antioxidant enzymes and the accumulation of proline but decrease the content of malondialdehyde (MDA), compared with wild-type plants. Moreover, several salt stress-related genes showed higher expression levels in transgenic plants, implying their potential to enhance salt tolerance. Our findings shed light on the role of SaR2R3-MYB genes in salt tolerance in S. alopecuroides.

Yellowhorn (Xanthoceras sorbifolium Bunge) is a valuable ornamental, medicinal, and woody oilseed species that is indigenous to China. The breeding improvement of yellowhorn has been hindered by a lack of suitable markers and sufficient information regarding the molecular diversity of this species. In this study, we conducted a comprehensive analysis of the yellowhorn genome to characterize the simple sequence repeat (SSR) loci. A total of 4,007,201 SSRs were successfully identified. Among these markers, mono-nucleotide SSRs were most abundant in the genome, while the tri-nucleotide SSRs accounted for the highest proportion in coding sequences. The GO and KEGG function enrichment analysis revealed that most SSR loci in coding sequences were associated with potential biological functions. Additionally, we used 30 pairs of primers to amplify SSR markers to gain a better understanding of the genetic variation in yellowhorn germplasms. The average values of observed heterozygosity and polymorphism information content were 0.625 and 0.517, respectively. Population structure, phylogeny and principal component analyses identified two distinct subclusters. Furthermore, yellowhorn germplasms with the same geographical distribution tended to group together. Moreover, a total of 26 yellowhorn core collections, which accounted for approximately 14.94% of the total yellowhorn germplasms, effectively represented the genetic diversity of all original germplasms. Our findings not only unveiled the genetic diversity and population structure of yellowhorn germplasms but also investigated the yellowhorn core collection, which will serve as a strong basis for yellowhorn management and genetic improvement.