OOS 22-2 - Dynamics of microbe-microbe competition and its contribution to plant disease

Phytopathogenic bacteria have evolved various molecular mechanisms that allow them to compete for limited resources and space in the phytobiome. Both Gram-positive and -negative bacteria produce polymorphic toxins but only Gram-negative bacteria produce Rearrangement Hot Spot (Rhs) toxins, which play an important role in intra- and interspecies competition. However, little is known about the abundance, function, and fitness impacts of these toxins on plant pathogenic bacteria and how these toxins contribute to niche exclusion. Here, we use a Hidden Markov Model (HMM) to mine the proteomes of five plant pathogenic bacterial genera. The number of Rhs-toxins among the proteomes mined ranged from 0 to 37 depending on the genera and species. Our findings suggest that Rhs-toxin abundance and diversity vary significantly between and within bacterial genera and may have been acquired via horizontal gene transfer. Preliminary data also indicate that soilborne bacteria encode a higher number of predicted Rhs-toxins than their foliar pathogen counterparts. Bacterial diseases are often challenging to manage; therefore, a fundamental understanding of the fitness factors that impact phytopathogenic bacteria in the phytobiome is necessary to develop novel management strategies