SMXL genes constitute a conserved gene family that is ubiquitous in angiosperms and involved in regulating various plant processes, including branching, leaf elongation, and anthocyanin biosynthesis, but little is known about their molecular functions in pear branching. Here, we performed genome-wide identification and investigation of the SMXL genes in 16 angiosperms and analyzed their phylogenetics, structural features, conserved motifs, and expression patterns. In total, 121 SMXLs genes were identified and were classified into four groups. The number of non-redundant SMXL genes in each species varied from 3 (Amborella trichopoda Baill.) to 18 (Glycine max Merr.) and revealed clear gene expansion events over evolutionary history. All the SMXL genes showed conserved structures, containing no more than two introns. Three-dimensional protein structure prediction revealed distinct structures between but similar structures within groups. A quantitative real-time PCR analysis revealed different expressions of 10 SMXL genes from pear branching induced by fruit-thinning treatment. Overall, our study provides a comprehensive investigation of SMXL genes in the Rosaceae family, especially pear. The results offer a reference for understanding the evolutionary history of SMXL genes and provide excellent candidates for studying fruit tree branching regulation, and in facilitating pear pruning and planting strategies.

Orchard soils have distinct stratification heterogeneity, while the responses of soil organic carbon mineralization (essentially microbial-mediated decomposition of organic matter, mainly producing CO₂) and bacterial communities to exogenous carbon addition in different soil layers are still unclear. In this study, a laboratory incubation experiment was conducted to investigate the differences in soil organic carbon mineralization characteristics and bacterial communities between glucose addition and no-glucose addition treatments in three soil layers (N1: 0–20 cm, N2: 20–40 cm, N3: 40–60 cm) of hilly orchards. The results demonstrated that soil organic carbon mineralization rates in all layers generally declined with increasing incubation duration. At D3, compared with the CK group, glucose addition increased the soil organic carbon mineralization rate by 3.28-fold, 9.30-fold, and 15.03-fold in the N1, N2 and N3 soil layers, respectively. Cumulative organic carbon mineralization followed the order N1 > N2 > N3. Compared with the CK treatment, glucose addition increased C₀ by 65.62% and 203.97% in the N2 and N3 soil layers, respectively. Two-way ANOVA was applied to quantitatively separate and compare the contributions of carbon addition treatment, incubation time and soil layer, and Beta diversity analysis revealed that soil layer was the primary driving factor. Under glucose addition, the key microorganisms related to organic carbon mineralization varied across soil layers: Gemmatimonadota and Acidobacteriota may exert a negative effect on soil organic carbon mineralization in orchard soils, whereas copiotrophic taxa, including Sphingomonas and Bacteroidota, contributed more strongly to carbon mineralization. Our results highlight the pronounced impact of labile carbon input on soil organic carbon mineralization within different soil layers, and reveal associations between soil bacterial communities and organic carbon mineralization in orchard ecosystems.