Comparative Analysis of Two Emerging Rice Seed Bacterial Pathogens

Abstract

Seed sterility and grain discoloration limit rice production in Colombia and several Central American countries. In samples of discolored rice seed grown in Colombian fields, the species Burkholderia glumae and B. gladioli were isolated, and field isolates were compared phenotypically. An artificial inoculation assay was used to determine that, although both bacterial species cause symptoms on rice grains, B. glumae is a more aggressive pathogen, causing yield reduction and higher levels of grain sterility. To identify putative virulence genes differing between B. glumae and B. gladioli, four previously sequenced genomes of Asian and U.S. strains of the two pathogens were compared with each other and with two draft genomes of Colombian B. glumae and B. gladioli isolates generated for this study. Whereas previously characterized Burkholderia virulence factors are highly conserved between the two species, B. glumae and B. gladioli strains are predicted to encode distinct groups of genes encoding type VI secretion systems, transcriptional regulators, and membrane-sensing proteins. This study shows that both B. glumae and B. gladioli can threaten grain quality, although only one species affects yield. Furthermore, genotypic differences between the two strains are identified that could contribute to disease phenotypic differences.

Multiplex PCR assay for simultaneous detection of six major bacterial pathogens of rice

“…; Fory et al . ). However, to date, no research for simultaneous detection of six rice seed‐borne target bacteria is carried out.…”

“…), or Bgu and Bgd (Fory et al . ). Recently, LAMP (Loop mediated isothermal amplification) has been used to detect Xoo and Xoc (Lang et al .…”

Differential regulation of toxoflavin production and its role in the enhanced virulence of Burkholderia gladioli

“…These symptoms are very similar to those associated with panicle infection by B. glumae. Although B. gladioli epidemics appear less frequently and this bacterium has relatively weaker virulence than B. glumae, these two bacterial species are often isolated from the same infected rice plants (Fory et al, 2014).…”

Understanding the direction of evolution in Burkholderia glumae through comparative genomics

“…Hence, there is an increasing interest in the mechanism by which B. glumae strain-specific virulence is modulated in response to host and environmental conditions (Fory et al 2014;Seo et al 2015). Recently, genome arrangement of B. glumae strains in the same host was found to show large differences (Seo et al 2015).…”

“…Indeed, rice-pathogenic Burkholderia species, including B. glumae, B. gladioli and B. plantarii, have evolved to adapt to different environments and hosts (Fory et al 2014;Seo et al 2015). Although comparison of 16 s ribosomal RNA sequences revealed that all species are very close, genomic analyses of many modules such as the secretion system, production of toxins, and distribution of clustered regularly interspaced short palindromic repeats (CRISPR)-mediated bacterial immune system displayed the diverse distribution in each strain (Seo et al 2015).…”