High expression level of transposase does not translate to fast evolution rate of a microbial species

Transposase are enzymes that help move transposon in and out of a host genome. Typically, transposon could randomly integrate into a microbial host genome. Depending on the site of integration, such transposon movement may result in disruption of genes or a neutral effect such as integration of transposon into a genomic safe spot. In some microbial species such as Pseudomonas syringae, RNA-seq transcriptome analysis has detected elevated expression of transposase. Thus, what are the likely implications of such high transposase relative abundance? One possibility is that there would be heightened integration of transposon into genomic sites of the host. Such integrations are probabilistic and random, and may not be able to set the genomic platform for the microbial species to evolve to a high fitness state. More likely, insertion of transposon into functional genes may disrupt cellular metabolism and physiological states, which in the best case scenario would result in cellular dysfunction, or in the worse case, cell death. Only under rare circumstances do a fortuitous sequence of transposon insertion managed to engender a better genomic endowment for the microbe to evolve a better phenotype and higher fitness level. Hence, high expression level of transposase does not necessarily imply a fast evolution rate of the microbial species.