As a crucial root vegetable, the phenomenon of bolting and flowering presents a significant challenge to the commercial value of carrot. However, the genetic mechanism of carrot bolting remains to be fully elucidated. In this study, we conducted a two-year cultivation experiment with a population of 240 carrots to examine traits associated with bolting. We conducted whole-genome sequencing on these carrots and subsequently performed population structure analysis, as well as genome-wide association studies (GWAS). A total of nine single nucleotide polymorphism (SNP) loci were identified across diverse environmental conditions that exhibited significant associations with bolting speed and other traits. Furthermore, within 93 candidate genes identified, the RING-domain zinc-finger protein LOC108205243 was determined to play a significant role in the regulation of bolting traits. The SNPs and candidate genes identified in this research may serve as molecular markers for bolting traits, thereby offering essential resources for genetic engineering breeding efforts aimed at managing bolting in carrots.

Biological soil crusts (BSCs) play key roles in arid, semi-arid regions and ecological marginal habitats. This study focused on four types of sand-fixing plantations established in 1990 in alpine sandy land (Salix psammophila, SL; Caragana korshinskii, NT; Salix cheilophila, WL; Populus simonii, XYY). Soil samples were collected from bare sand, algae crusts, and moss crusts. Soil particle size distribution, physicochemical properties, and enzyme activity were determined. Then bacterial communities were analyzed using high-throughput (Illumina) sequencing and the correlations among these three factors were examined. The results showed that: (1) From bare sand to algae and moss crusts, the content of fine particles (clay + silt) gradually increased. (2) Soil water content (SWC), nutrients and enzyme activities increased progressively. (3) In the study area, the dominant bacterial phyla of BSCs included Pseudomonadota, Cyanobacteria, Actinobacteriota and Vibrionota. Principal Coordinates Analysis (PCoA) and Analysis of Similarities (ANOSIM) results showed that BSCs drive the differentiation of bacterial communities during succession, while forest stands influence their spatial distribution. (4) Spearman’s correlation and redundancy analysis (RDA) showed that available phosphorus (AP), alkaline hydrolyzable nitrogen (AN), soil organic matter (SOM), catalase (CAT), pH, soil water content (SWC), and alkaline phosphatase (ALP) are key physicochemical factors shaping the bacterial community structure of BSCs. Mantel’s test confirmed that these variables mediated BSCs’ bacterial community structure. This study elucidates the mechanisms underlying ecological restoration via BSCs and provides a theoretical basis for future restoration efforts in alpine sandy land.

Background: Carbon partitioning and energy supply in plants are largely dictated by sucrose metabolism, which is coordinately mediated by sucrose phosphate synthase (SPS), sucrose synthase (SUS), and invertase (INV). Carrot is an economically important root crop worldwide. As the major transport and storage disaccharide, sucrose modulates root osmotic potential and sweetness depending on its accumulation level. However, the genome-wide characteristics of the SPS, SUS, and INV gene families in carrot, as well as their expression dynamics across developmental stages and under stress conditions, remain unknown. Methods: In this study, we identified these gene families in carrot and characterized their phylogenetic relationships, gene structures, conserved protein motifs, chromosomal distribution, and expression profiles across developmental stages and under abiotic treatment with stress-inducing agents. Results: A total of 5 SPS, 8 SUS, and 19 INV genes were identified in carrot. Phylogenetic analysis revealed that members within the same subfamily share similar exon–intron structures and conserved motif compositions. Segment duplication, rather than tandem duplication, emerged as the primary driver of family expansion. Transcript profiling revealed that DcSPS, DcSUS, and DcINV paralogs exhibit varied spatiotemporal expression signatures across tissues and developmental stages, and several are robustly activated as fleshy roots expand. Upon abiotic challenge, these genes undergo differential transcriptional modulation, and many members show pronounced induction under NaCl or exogenous ABA treatment. Conclusions: Collectively, these findings provide a comprehensive inventory of the SPS, SUS, and INV gene families in carrot and generate testable hypotheses regarding their potential roles in sucrose metabolism. The identified genes and their expression profiles offer a valuable genetic resource for future functional studies and sucrose-based quality improvement in this crop.

The fungal communities within biological soil crusts (BSCs) of alpine sandy lands remain poorly understood, particularly regarding their associations with long-term plantation restoration. Four types of sand-fixing plantations (Salix psammophila, Salix cheilophila, Caragana korshinskii, and Populus simonii) in the Gonghe Basin were chosen as study sites, and bare sand, algae crust, and moss crust samples were obtained from each plot. Soil physicochemical properties and extracellular enzyme activities were measured, and the fungal community was characterized by Illumina high-throughput sequencing of the ITS1 region. We systematically examined how key predicted guilds of fungal communities and their environmental factors changed across crust types, and characterized the differentiation of predicted guilds. Our main results are summarized below: (1) Ascomycota and Basidiomycota dominated at the phylum level, while Preussia, Alternaria, Paraphoma, and Endocarpon dominated at the genus level. (2) Moss crust had the highest fungal richness and evenness, followed by algae crust, whereas bare sand had the lowest values. Furthermore, PCoA-ANOSIM further revealed marked differences in BSC fungal community structure among the plantations. (3) Spearman’s correlation analysis, CCA, and the Mantel test indicated that the plantations were associated with fungal community differentiation through variation in edaphic physicochemical properties and extracellular enzymatic activity. Furthermore, pH, AK, and AP were associated with fungal community composition in both crust types, with ALP and SUC additionally important in algae and moss crusts, respectively. (4) FUNGuild predictions indicated that Undefined Saprotroph was the dominant predicted guild and that saprotrophy was the dominant trophic mode in the BSC fungal communities of the study area. This study revealed the fungal community composition and organization of BSCs across various crust types, and identified the factors associated with these communities in different artificial sand-fixing plantations in alpine sandy land. These findings may offer a microbiological foundation for restoring alpine sandy land ecosystems in the future.

Biological soil crusts (BSCs) are critical components of alpine sandy land ecosystems, yet how their diazotrophic communities respond to plantation type and successional stage remains largely unknown. This study examined diazotrophic community differentiation in BSCs under four sand-fixing plantations (Salix psammophila SL, Caragana korshinskii NT, Salix cheilophila WL, Populus simonii XYY) across three successional stages in an alpine sandy land. Soil properties, microbial biomass, and enzyme activities were measured, along with nifH gene sequencing (Illumina), to characterize community composition and its relationships with environmental factors along BSCs succession. The results indicate that Skermanella, Mastigocladus, and Nostoc were the dominant diazotrophic groups in the study area. The Nostoc was the dominant genus across all plantation types, with the highest average relative abundance (37.92%) recorded in moss crusts under the XYY plantations. Diazotrophic α-diversity increased with BSCs succession, and β-diversity analysis (PCoA with ANOSIM) demonstrated significant community differentiation among plantation types (variance explanation = 50.91%, R = 0.59458, p = 0.001). Spearman’s and redundancy analysis (RDA) showed that sand-fixing plantations drive the differentiation of diazotrophic communities by regulating soil physicochemical properties and microbial metabolism. Furthermore, the diazotrophic communities in moss crusts exhibited stronger environmental responsiveness than those in algae crusts. In the COG functional categories, J (translation and ribosomal biogenesis, 7.92%), E (amino acid metabolism, 10.14%), and C (energy production, 7.11%) were identified as the core foundational functions of BSCs in the study area. The relative abundances of these functional categories showed convergence. In summary, different plantations were associated with distinct diazotrophic community compositions, and these associations were largely mediated by soil environmental factors. Concurrently, BSC succession covaried with enhanced differentiation in community structure and functional traits. These patterns are consistent with a stepwise response cascade linking vegetation and soil properties to diazotrophic communities and nitrogen metabolism functions. This study provides a theoretical basis for enhancing the stability and long-term restoration of artificial ecosystems by regulating diazotrophic communities in BSCs in alpine sandy land.

The ecological stoichiometric traits of forest floor material nutrient resorption in forest ecosystems. However, systematic insights into nutrient allocation and scaling during the transformation of plant organs to forest floor material remain limited. This study examined six representative tree species on the southern slope of the Qilian Mountains, quantifying the carbon (C), nitrogen (N), and phosphorus (P) contents and their stoichiometric characteristics in leaves, branches, and mixed forest floor material. Allometric relationships between N and P were analyzed using the standardized major axis regression. Coniferous species exhibited a conservative strategy with high C/N and C/P ratios, whereas broad-leaved species and mixed forests exhibited nutrient-enrichment strategies. During the organ-to-forest floor material transformation, N and P contents significantly reduced, whereas C/N and C/P ratios increased, indicating strong nutrient resorption. N and P were positively associated with plant organs and forest floor material, with isometric relationships (b = 1.06 and 0.98 for plant organs and forest floor material, respectively). Because the slopes did not differ significantly from 1 (p > 0.05), the N:P ratio remained relatively constant, with no significant P limitation. This indicates that tree species regulate forest floor material quality through divergent nutrient utilization strategies, modulating nutrient cycling. This study provides a theoretical foundation for the ecological restoration and stand structure optimization of alpine forests.