FIG 2.

Selected genes and pathways enriched in biocrusts versus hypoliths. (A) Heatmap of DNA repair genes significantly more abundant in biocrust communities versus hypolith communities. Genes are shown in rows and samples are shown in columns. Heatmap colors show the relative abundances of genes scaled by row. Rows are labeled by gene names. Sample names are colored according to the dominant primary producer and environment. Hypolith samples are indicated by cool colors and biocrust samples are shown by warm colors (light blue, moss hypolith; dark blue, cyanobacterial hypolith; orange, moss biocrust; red, cyanobacterial biocrust). Columns and rows were clustered for visualization purposes using the complete linkage method. DNA repair related functions are indicated by superscripts after the gene names as follows: 1, DNA polymerase III; 2, nucleotide excision repair; 3, replication restart; 4, homologous recombination-based repair; 5, mismatch recognition; 6, endonuclease; and 7, base excision repair. A list of genes with the corresponding KEGG orthology numbers can be found in Table S6. (B–D) Selected two component systems enriched in biocrust crust communities. Two component systems canonically contain a sensor kinase (shown as rectangles within the membrane) and response regulator (shown as squares), which mediate downstream cellular responses when phosphorylated. Additional components specific to a particular system are shown in ovals. Phosphate (P) is indicated by yellow circles. Each protein is labeled by the name of the gene that encodes it. Blue indicates genes significantly more abundant in biocrust compared to hypolith communities (P < 0.01). Gray shows genes with P-values > 0.01. Panel B contains lifestyle-related two component systems, C contains two component systems related to redox signals and catabolites, and D contains systems related to nutrient limitation and environmental stressors. This figure highlights systems with strong evidence (i.e., multiple significant genes within the system) of being more abundant in biocrusts versus hypoliths. A complete list of genes within the KEGG two component system pathway that were significant is provided in Table S6. (E) Diagram of the KEGG flagellar assembly pathway. Genes significantly more abundant in biocrusts versus hypoliths (P < 0.01) are indicated in bold text. Genes where P > 0.01 are not bolded. KEGG orthology numbers corresponding to gene names are listed in Table S6. (F) Schematic of bacterial secretion systems significantly more abundant in biocrust compared with hypolith communities. Each component is labeled with a gene name. Names in bold represent significant genes (P < 0.01) and names in gray represent nonsignificant genes (P > 0.01). A full list of bacterial secretion system genes significantly more abundant in biocrusts versus hypoliths can be found in Table S6. The pathway schematic is based on the KEGG secretion system diagram, (89), and (49).