Phylogenetic analysis, molecular characterization and virulence profiling based on toxoflavin gene of an Indian BG1 strain of Burkholderia glumae causing panicle blight of rice

Sanjeev Kumar; Kalyan K Mondal; Thungri Ghoshal; Aditya Kulshreshtha; B Sreenayana; M Amrutha Lakshmi; S Mrutyunjaya; E R Rashmi; N S Kalaivanan; Aditi Kundu; Chandra Mani

doi:10.1007/s13205-023-03660-6

Phylogenetic analysis, molecular characterization and virulence profiling based on toxoflavin gene of an Indian BG1 strain of Burkholderia glumae causing panicle blight of rice

3 Biotech. 2023 Jul;13(7):239. doi: 10.1007/s13205-023-03660-6. Epub 2023 Jun 17.

Affiliations

¹ Division of Plant Pathology, ICAR, Indian Agricultural Research Institute, New Delhi, India.
² Division of Agricultural Chemicals, ICAR, Indian Agricultural Research Institute, New Delhi, India.

PMID: 37337525
PMCID: PMC10276795 (available on 2024-07-01)
DOI: 10.1007/s13205-023-03660-6

Abstract

Bacterial panicle blight (BPB) caused by Burkholderia glumae (BG) has become significantly more prevalent in the rice-growing regions of North India. Based on virulence screening and in vitro quantification of toxoflavin, the BG strains were classified as hyper- (BG1 and BG3), moderate- (BG2, BG4, BG6, BG8, and BG9), and hypo- (BG5, BG7, and BG10) virulent. Plant inoculation assays with cell-free culture filtrate revealed strains with higher toxoflavin-producing ability had higher virulence. Based on 16S rRNA sequence, 6 isolates from Uttar Pradesh were grouped in clad C1; whereas, clad C2 exhibited 4 isolates, two each from Delhi and Uttar Pradesh. Strain BG1 being the most virulent Indian strain from Uttar Pradesh was further profiled for 11 tox genes. We found all the 11 tox genes present in strain BG1. In toxRABCDE cluster, all tox genes showed high similarity to B. glumae BGR1 except toxB, whereas in toxFGHIJ cluster toxF, toxG, toxH and toxI shared maximum similarity to B. glumae 336gr-1. tox genes of BG1 exhibited homology as well as divergence with B. gladioli. The domain prediction and protein association network analysis indicated the possible involvement of tox genes in the toxoflavin biosynthesis. As per our knowledge, this is the first report in India on characterization of tox genes cluster in B. glumae. Altogether, our study unravels a reliable method for identifying and characterizing B. glumae using tox genes and its relationship with disease production.

Supplementary information: The online version contains supplementary material available at 10.1007/s13205-023-03660-6.

Keywords: Culture filtrate; Isolates; Quantification; Symptoms; Tox gene.

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