PLANT HOST AFFECTS BACTERIA-BACTERIA INTERACTIONS

The root surroundings represent one of the most complex environments on earth. In recent years evidence for plant species-specific microbiome demonstrated that the genus Pseudomonas is among the most abundant bacterial taxa in several rhizospheres. In the current study, we aim to investigate the mode of roots colonization by three distinguished Pseudomonas strains and the interactions occurring during co-inoculation. We isolated and characterized three Pseudomonas spp. from wheat rhizosphere (NT0124, NT0128 and NT0133) and found that all isolates separately effectively colonized wheat but not cucumber roots. Moreover, each isolate occupied specific niche on wheat roots (root tip vs. distant from the tip vs. scattered). However, co-inoculation of several isolates together on wheat roots affected the localization of two of isolates on the roots. In addition, co-inoculation also influenced bacteria-bacteria interaction and caused competition between isolates. In an attempt to better understand plant host influence on bacterial interaction, we examined whether competition on colonization depends on physical presence of the roots, by examining the isolates abundance while growing in homogeneous and heterogeneous liquid culture. Surprisingly, we found that adding wheat roots extracts to the media was sufficient to influence bacteria-bacteria interaction. Addition of cucumber root extracts had no effect on bacteria abundance thus no competition was observed.
Understanding plant-bacteria and bacteria-bacteria interactions can enhance our ability to control the root microbiome and improve the beneficial effects of bacterial inoculation via successful colonization.