biosecurity built on science

Detection and identification of Australian Xanthomonas species

causing bacterial leaf spot

Rebecca RoachPhD student

Plant Biosecurity Cooperative Research Centre

biosecurity built on science

BackgroundBacterial leaf spot (BLS) Four common species: X. vesicatoria X. euvesicatoria X. perforans X. gardneri

Which species cause BLS in

Australia?

biosecurity built on science

Project aims

Which bacterial species cause BLS in Australia? How are these species distributed?→Characterise with MLSA and biochemical analyses

How diverse are these pathogen populations? How does pathogenicity vary?→Investigate with whole genome sequences

= Improved disease management

biosecurity built on science

Collection and characterisation Isolates sourced from

tomato, capsicum and chilli crops

Biochemical analyses: oxidase, catalase, KOH (gram reaction), starch, pectin, YDC

Specific PCR

MLSA of 64 isolates – gyrB, efp, dnaK, atpD

biosecurity built on science

Genomic analysis

44 genomes of collected Xanthomonas isolates

Whole genome phylogeny Pan-genome analysis Average nucleotide identity Cazyme analysis Effector protein repertoires Plasmid diversity

biosecurity built on science

Race trials

Differential lines in capsicum contain resistance genes

Assign races to collected Xanthomonas isolates

Results inform disease management

biosecurity built on science

Impact of findings

Diversity, pathogenicity and distribution inform management strategies

Project will result in framework for detecting and understanding xanthomonas pathogens

This will be applicable to exotic species

biosecurity built on science

Thank you

Epic team:Dr. Brendan Rodoni, Dr. Rachel Mann, Dr. Cherie Gambley, Dr. Roger Shivas, Dr. Toni ChapmanAgribio/ La Trobe University,QDAF, PBCRC, HIA

For more information, please emailroach.r@students.latrobe.edu.au