Correlation between the distribution of prx and the eco-physiological properties and genome sizes of cyanobacteria. The number of prx in each species was determined based on the genes encoding PRX in the genomes. Percentages represent total prx as a percentage of total proteins. Strain names and the eco-physiological properties are as in Figure 1 and Additional file 1. Statistical analyses on the relationship between the distribution of genes encoding PRXs from different sub-families and the properties of 37 cyanobacterial organisms were performed using the Spearman Rank Correlation test (R), respectively. For the test of the distribution of prx and the genome size, cellular morphology, habitat and eco-physiological properties of 37 cyanobacterial organisms, the X
is GS, U/E, MAR/FRE or UM/UF/UH/FM/FF and the Y
is the total number of prx or the number of prx belonging to different sub-families and the in each cyanobacterial organisms. Note: X, the independent variable; Y, the dependent variable; GS, genome size (from small to large); U/F, unicellular or filamentous; MAR /FRE, marine or freshwater; UM/UF/UH/FM/FF, unicellular marine, unicellular freshwater, unicellular hot-spring, filamentous marine or filamentous freshwater. Spearman Rank test indicated that the distribution of some PRX family such as PRX-like or 1-Cys PRX correlate well with the eco-physiological properties and genome sizes of cyanobacteria (“*”, p-value <=0.01; “**”, p-value <=0.001).