Discerning the role of a functional arsenic-resistance cassette in the evolution and adaptation of a rice pathogen

Abstract

Arsenic is highly toxic element to all forms of life and is a major environmental contaminant. Understanding acquisition, detoxification and adaptation mechanisms in bacteria that are associated with the host in arsenic-rich conditions can provide novel insights into the evolutionary dynamics of host–microbe–environment interactions. In the present study, we have investigated an arsenic-resistance mechanism acquired during the evolution of a particular lineage in the population of Xanthomonas oryzae pv. oryzae, which is a serious plant pathogen infecting rice. Our study revealed the horizontal acquisition of a novel chromosomal 12 kb ars cassette in X. oryzae pv. oryzae IXO1088 that confers high resistance to arsenate/arsenite. The ars cassette comprises several genes that constitute an operon induced in the presence of arsenate/arsenite. Transfer of the cloned ars cassette to X. oryzae pv. oryzae BXO512, which lacks the cassette, confers an arsenic-resistance phenotype. Furthermore, the transcriptional response of X. oryzae pv. oryzae IXO1088 under arsenate/arsenite exposure was analysed using RNA sequencing. Arsenic detoxification and efflux, oxidative stress, iron acquisition/storage, and damage repair are the main cellular responses to arsenic exposure. Our investigation has provided insights into the existence of a novel detoxification and adaptation mechanism within the X. oryzae pv. oryzae population to deal with high-arsenic conditions outside the rice plant.

Ecological Responses of Maize Rhizosphere to Antibiotics Entering the Agricultural System in an Area with High Arsenicals Geological Background

“…This could be explained by the facts that soil microbial community were primarily determined by high arsenic background; and the ability of microbes in arsenic-polluted soil to co-resist, cross-resist, co-regulate, or biofilm-induce the antibiotics presence [ 62 , 63 ]. Meanwhile, organic arsenic may be a primordial antibiotic, and the host in arsenic-rich conditions can pose evolutionary dynamics of host–microbe–environment interactions and present existence of a novel detoxification and adaptation mechanism [ 64 , 65 ]. However, the timing interaction of antibiotics with the soil environment could reduce this promotion effect and alter the microbial processes [ 66 , 67 ].…”