Flagellar biosynthesis and motility are subject to a four-tiered transcriptional regulatory circuit in Pseudomonas, and the master regulator FleQ appears to be the highest-level regulator in this hierarchical regulatory cascade. Pseudomonas stutzeri A1501 is motile by a polar flagellum; however, the motility and regulatory mechanisms involved in this process are unknown. Here, we searched the A1501 genome for flagella and motility genes and found that approximately 50 genes, which were distributed in three non-contiguous chromosomal regions, contribute to the formation, regulation and function of the flagella. The non-polar mutation of fleQ impaired flagellar biosynthesis, motility and root colonization but enhanced biofilm formation. FleQ positively regulates the expression of flagellar class II–IV genes, suggesting a regulatory cascade that is coordinated similar to that of the well-known P. aeruginosa. Based on our results, we propose that flagellar genes in P. stutzeri A1501 are regulated in a cascade regulated by FleQ and that flagellum-driven motility properties may be necessary for competitive rhizosphere colonization.

Using linker peptide LP4/2A for multiple gene transformation is considered to be an effective method to stack or pyramid several traits in plants. Bacillus thuringiensis (Bt) cry gene and epsps (5-enolpyruvylshikimate-3-phosphate synthase) gene are two important genes for culturing pest-resistant and glyphosate-tolerant crops. We used linker peptide LP4/2A to connect the Bt cry1Ah gene with the 2mG2-epsps gene and combined the wide-used manA gene as a selective marker to construct one coordinated expression vector called p2EPUHLAGN. The expression vector was transferred into maize by Agrobacterium tumefaciens-mediated transformation, and 60 plants were obtained, 40% of which were positive transformants. Molecular detection demonstrated that the two genes in the fusion vector were expressed simultaneously and spliced correctly in translation processing; meanwhile bioassay detection proved the transgenic maize had preferable pest resistance and glyphosate tolerance. Therefore, linker peptide LP4/2A provided a simple and reliable strategy for producing gene stacking in maize and the result showed that the fusion gene transformation system of LP4/2A was feasible in monocot plants.