Genome-wide identification of root colonization fitness genes in plant growth promoting Pseudomonas asiatica employing transposon-insertion sequencing

Pseudomonas spp. are well-studied plant growth promoters, particularly in the context of root colonization. However, the specific genetic factors that determine its fitness in the rhizosphere remain largely unexplored. This study breaks new ground by employing transposon insertion sequencing (Tn-Seq) to identify the genetic factors in Pseudomonas asiatica JR11 that are crucial for colonizing corn roots.

We created a transposon mutant library of P. asiatica JR11 with 91,884 insertion sites and subjected it to three consecutive enrichment cycles within the corn root system. A total of 79 genes were identified as essential for root colonization (negatively-selected), while 22 genes were found to counteract root colonization efficiency (positively-selected), with both sets being commonly present across all three cycles. These genes involve amino acid metabolism, cell wall biosynthesis, and protein functions. Additionally, we found four negatively-selected and four positively-selected hypothetical proteins that consistently influenced root colonization fitness.

The identification of these molecular determinants opens up exciting possibilities for further research. Understanding these pathways could lead to the development of novel strategies for enhancing the fitness of P. asiatica JR11 during corn root colonization, with potential implications for plant growth promotion and agricultural practices.