Corn Goss’s wilt in Manitoba: Pathogenicity and Genetic Diversity of the...

Corn Goss’s wilt in Manitoba: Pathogenicity and Genetic Diversity of the pathogen
Atta Soliman1, Lorne R. Adam1, Pratisara Bajracharya3, Alexander Shumilak1, Shirley Otukpa1, James Tambong2, Fouad Daayf1.
1Department
of Plant Science, University of Manitoba, Winnipeg MB, Canada; 2AAFC, Eastern Cereal & Oilseed Research Centre, Ottawa, ON, Canada;
3Manitoba
Agriculture, Food & Rural Development, Carman, MB, Canada
Introduction
Clavibacter michiganensis subsp nebraskensis (Cmn) causes Goss’s wilt and blight in corn. Our study aims to develop a sound pathogenicity testing method and to
investigate Cmn population diversity in Manitoba by assessing pathogenic and genetic variability. The Cmn isolates were collected from infected fields in southern
Manitoba. After testing seven different inoculation methods, the pathogenicity was assessed in the greenhouse using two of the newly developed methods that
were closest to natural conditions. Generally, the Cmn isolates tested, which represent Cmn populations in Manitoba in the 2014 season, were genetically diverse.
The pathogenicity and aggressiveness of Cmn isolates followed the phylogenic classification based on three molecular markers.
Materials and Methods


Isolation of Cmn from symptomatic from field to create collection
Corn (P7443) leaves 3, 4 and 5 were inoculated in the greenhouse with the Cmn isolate collection for 2014 and assessed for lesion length and disease severity
over time. The total area under the disease progress curve (AUDPC) was calculated for 14dpi.
gDNA was extracted, concentration adjusted and PCR for ISSR markers rated.

Objectives
Genetic Diversity
Characterization of Cmn population structure in Southern Manitoba
ISSR
Isolation procedures
Symptomatic Leaf sample
(+)
Immunostrip test
Isolation
Cmn 14-5-1
Cmn 14-3-4
Cmn 14-4-1
Cmn 14-2-1
Cmn 14-1-1
DOAB 406
DOAB 405
DOAB 404
DOAB 403
DOAB 232
DOAB 395
DOAB 393
DOAP 394
DOAB 392
DOAB 391
DOAB 391
Cmn 7
Cmn 2
M
M
CNS/NBY media
Orange
/
Apricot color
Pathogenicity
(+)
DNA extraction &PCR
Bioassay
Genetic diversity (ISSR)
Symptoms
Cmn
Pathogenicity test
Collaborators
0
1
Pathogenicity scale
2
3
Control – no lesion other than wound
Chlorosis or reddening of the tissue – no necrosis
Chlorosis or reddening with freckling, up to 10% necrosis
0
Chlorosis or reddening with freckling, 10% - 25% necrosis, or wilt
Conclusions
ISSR markers showed diversity in Cmn isolates.
The pathogenicity of Cmn isolates followed the phylogenetic classification.
Acknowledgements
4
26-50% necrosis
5
51-75% necrosis
6
>76 % necrosis