Genome-Wide Identification of LATERAL ORGAN BOUNDARIES DOMAIN (LBD) Transcription Factors and Screening of Salt Stress Candidates of Rosa rugosa Thunb

SIMPLE SUMMARY: The transcription factor family LBD were well-known as regulator of plant development. Several recent studies indicated LBD genes response to abiotic stresses and abscisic acid. The salt tolerant rose (Rosa rugosa) distribute wildly in coastal saline sands are ideal materials of exploring the salt -responsive LBD genes. We found 41 RrLBDs from genome of wild rose and classified them into Classes I and II. Interestingly, many plant hormone response sites and abiotic stress response sites were predicted in promoters of some RrLBDs. In them, five RrLBDs (RrLBD12c, RrLBD25, RrLBD39 and RrLBD40) were significantly induced or depressed by salt stress. We predicted the five genes as salt response candidate genes of wild rose and the sites in their promotors maybe pointcut for further study. ABSTRACT: LATERAL ORGAN BOUNDARIES DOMAIN (LBD) transcription factors are regulators of lateral organ morphogenesis, boundary establishment, and secondary metabolism in plants. The responsive role of LBD gene family in plant abiotic stress is emerging, whereas its salt stress responsive mechanism in Rosa spp. is still unclear. The wild plant of Rosa rugosa Thunb., which exhibits strong salt tolerance to stress, is an ideal material to explore the salt-responsive LBD genes. In our study, we identified 41 RrLBD genes based on the R. rugosa genome. According to phylogenetic analysis, all RrLBD genes were categorized into Classes I and II with conserved domains and motifs. The cis-acting element prediction revealed that the promoter regions of most RrLBD genes contain defense and stress responsiveness and plant hormone response elements. Gene expression patterns under salt stress indicated that RrLBD12c, RrLBD25, RrLBD39, and RrLBD40 may be potential regulators of salt stress signaling. Our analysis provides useful information on the evolution and development of RrLBD gene family and indicates that the candidate RrLBD genes are involved in salt stress signaling, laying a foundation for the exploration of the mechanism of LBD genes in regulating abiotic stress.