Participation of the type VI secretion system in the endophytic colonization of phosphate solubilizing bacteria

LORDA, GRACIELA SUSANA; BOGINO, PABLO; LUDUEÑA LILIANA; ANGELINI JORGE; LUCERO, CINTHIA TAMARA; NIEVAS, FIORELA; TAURIAN TANIA

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Congreso; XXX REUNION LATINOAMERICANA DE RIZOBIOLOGÍA V CONFERENCIA LATINOAMERICANA DE MICROORGANISMOS PROMOTORES DEL CRECIMIENTO VEGETAL; 2021

There are different types of secretion systems in bacteria that transfermolecules both to the extracellular medium and to the interior of adjacent cells.In mutualistic endophytic bacteria, type VI secretion system (T6SS) is related toimportant functions, such as interbacterial competition, stress response, quorumsensing, biofilm formation and symbiosis. The endophytic population associatedwith different plants has a high number of genes related to T6SS, which suggeststhat it would play an important role in its interaction with the plant. Phosphatesolubilizing bacteria constitute a group of bacteria of great relevance in the rhizosphereas they provide phosphorus to plants. Among them, those with endophyticcolonization capacity have adaptive and survival advantages. The aim of this studywas to analyze if the T6SS of a native peanut bacterium with phosphate solubilizingcapacity is involved in its endophytic colonization in this legume. Enterobactersp. J49 strain was used due its efficient ability to solubilize significant amounts ofinsoluble phosphates and to promote the growth of peanut, corn and soybeanplants. Initially, an in silico analysis looking for genes related to T6SS in the genomeof the Enterobacter sp. J49 strain was developed. It was possible to identify,with the exception of the tssE gene, all the tss genes in its genome. Subsequently,a mutant of the Enterobacter sp. J49 strain was obtained by interrupting one of theessential tss genes. Then, the Enterobacter sp. J49Δhcp strain obtained was inoculatedon peanut plants in order to analyze its colonization capacity. The resultsobtained indicated a significant decrease in the epiphytic and endophytic aerialand radical colonization of the mutant with respect to the wild strain. It is possibleto conclude that T6SS, although not essential, would participate in bacterialcolonization, either accelerating the infection, or promoting other mechanismsinvolved in it.