Location: Crop Protection and Management ResearchTitle: Detecting genotypic variation among the single spore isolates of Pasteuria penetrans population occuring in Florida using SNP-based markers
|Soumi, Joseph - University Of Florida|
|Schmidt, L - Syngenta Crop Protection|
|Timper, Patricia - Patty|
|Hewlett, T - Syngenta Crop Protection|
|Watrin, C - Syngenta Crop Protection|
|Mekete, T - University Of Florida|
Submitted to: Society of Nematology Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/20/2015
Publication Date: 12/5/2015
Citation: Soumi, J., Schmidt, L.M., Timper, P., Hewlett, T., Watrin, C., Mekete, T. 2015. Detecting genotypic variation among the single spore isolates of Pasteuria penetrans population occuring in Florida using SNP-based markers [abstract]. Society of Nematology Abstracts. 47:269.
Technical Abstract: Pasteuria penetrans is a naturally occurring soil-borne endospore-forming bacterium, which functions as a castrating parasite of plant-parasitic nematodes belonging to the genus Meloidogyne. Pasteuria penetrans is established as an effective biological control agent for control and management of root knot nematodes (RKN). Previous studies have suggested that field populations of P. penetrans are heterogeneous and also suggest that individuals within a given population vary in degree of host specificity and virulence towards the same host. This study examined genotypic variation and virulence characteristics of six clonal P. penetrans spore lines produced though single spore infections of individual host nematodes exposed to a field population of P. penetrans isolated from Meloidogyne arenaria in Florida. Genetic variability of six clonal lines of P. penetrans was assessed based upon sequence analysis of six protein-coding genes and the 16S rRNA gene. The results showed an average of one SNP for every 69 bp in the 16S rRNA partial cds while protein-coding sequences did not show any variation among the clonal lines. Hierarchical cluster analysis of 16S rRNA sequences placed the clones into three groups: Clonal lines 16ssp, 30ssp, 25ssp and 26ssp clustered together and separate from the distinct clonal lines 17ssp and 18ssp. Evaluation of the clonal lines to attach and parasitize different species of RKN and populations obtained from different geographic locations resulted in significant differences in spore attachment and virulence amongst the clones. Clonal lines 16ssp and 30ssp provided the highest rates of spore attachment (24-40spores/juvenile) and were positive for infectivity in all RKN species tested, while 18ssp provided the lowest attachment rate (1-11spores/juvenile) and lowest level of spore production on M. arenaria. In summary, our study demonstrated that a field population of P. penetrans is highly heterogeneous with regard to homology in the 16S rRNA gene and individual members demonstrate varying levels of host virulence. For example 16ssp and 30ssp demonstrated a wide host range and robust virulence among RKN species, while 18ssp demonstrated a tighter host range and lower overall virulence. Our study demonstrates that the SNP marker based on the variable region (5’ end) of 16S rRNA region gives sufficient resolution to discriminate single spore isolates of P. penetrans and has the potential to be developed as a tool for discriminating host specificity and virulence.