Genetic Diversity of Type 3 Secretion System in Burkholderia s.l. and Links With Plant Host Adaptation

Abstract

Burkholderia sensu lato species are prominent for their diversity of hosts. The type 3 secretion system (T3SS) is a major mechanism impacting the interactions between bacteria and eukaryotic hosts. Besides the human pathogenic species Burkholderia pseudomallei and closely affiliated species, the T3SS has received little attention in this genus as in taxonomically and evolutionary close genera Paraburkholderia, Caballeronia, Trinickia, and Mycetohabitans. We proceeded to identify and characterize the diversity of T3SS types using the genomic data from a subset of 145 strains representative of the species diversity found in the Burkholderia s.l. group. Through an analysis of their phylogenetic distribution, we identified two new T3SS types with an atypical chromosomal organization and which we propose to name BCI (Burkholderia cepacia complex Injectisome) and PSI (Paraburkholderia Short Injectisome). BCI is the dominant T3SS type found in Burkholderia sensu stricto (s.s.) species and PSI is mostly restricted to the Paraburkholderia genus. By correlating their distribution with the ecology of their strains of origin, we propose a role in plant interaction for these T3SS types. Experimentally, we demonstrated that a BCI deficient B. vietnamiensis LMG10929 mutant was strongly affected in its rice colonization capacity.

Reduced and Nonreduced Genomes in Paraburkholderia Symbionts of Social Amoebas

“…The BurBor-like T3SS operon is closely related to one found in the plant pathogen Robbsia andropogonis . It includes a needle apparatus uncommon among Burkholderia T3SS that is used to inject rhizobitoxine into a wide range of plant hosts ( 60 , 72 ). The adjacent T6SS operon is closely related to T6SS-5 shared by B. mallei , B. pseudomallei , and B. thailandensis .…”

Bacterial family-specific enrichment and functions of secretion systems in the rhizosphere

“…Many of these are considered core taxa of plant microbiomes, such as Rhizobiales, Burkholderiales, Pseudomonadales , the Bacteroidetes phylum (Banerjee et al ., 2018), Oxalobacteraceae, Comamonadaceae and Xanthomonadaceae (Schneijderberg et al ., 2020, Johnston-Monje et al ., 2021). A predominant focus in studies of T3SS and plant-associated bacteria has been on Pseudomonas , root-nodulating Rhizobiales and other genera within this order (Stringlis et al ., 2019, Wallner et al ., 2021, Boak et al ., 2022, Zboralski et al ., 2022). This study identified additional families likely benefiting from T3SS and T6SS, such as Oxalobacteraceae, Comamonadaceae and Caulobacteraceae .…”

Comparative genomics support reduced-genome Paraburkholderia symbionts of Dictyostelium discoideum amoebas are ancestrally adapted professional symbionts

“…The BurBor-like T3SS operon is closely related to one found in the plant pathogen Robbsia andropogonis. It includes a needle apparatus uncommon among Burkholderia T3SS that is used to inject rhizobitoxine into a wide range of plant hosts (Wallner et al 2021;Mannaa et al 2019). The adjacent T6SS operon is closely related to T6SS-5 shared by B. mallei, B. pseudomallei, and B. thailandensis.…”