Resistance to Candidatus Liberibacter solanacearum (Lso) in the wild potato Solanum microdontum

Authors: Bamberg, John; COOPER, RODNEY - US Department Of Agriculture (USDA); Fenstemaker, Sean

Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/23/2024
Publication Date: 9/7/2024
Citation: Bamberg, J.B., Cooper, R.W., Fenstemaker, S.M. 2024. Resistance to Candidatus Liberibacter solanacearum (Lso) in the wild potato Solanum microdontum. American Journal of Potato Research. https://doi.org/10.1007/s12230-024-09969-z.
DOI: https://doi.org/10.1007/s12230-024-09969-z

Interpretive Summary: The US potato crop produces a remarkable yield of nutritious food every year. But USDA and state partners are working on making it even better. A key way to do that is to breed better varieties. The US Potato Genebank (USPG) at Sturgeon Bay, Wisconsin has about 6,500 samples of wild and cultivated potato for use for raw materials to support that breeding effort. This includes samples of the wild species Solanum microdontum (mcd). Previous reports suggested that some individuals of mcd have resistance to the bacteria that causes the very serious disease of potato called "Zebra Chip". We here report screening of a broad spectrum of mcd and discovery of a few individuals with very strong resistance. Since mcd is relatively closely-related to the potato of commerce, breeding this valuable trait into new varieties should be relatively simple and rapid. These resistant lines will also be valuable standards for basic study of the disease.

Technical Abstract: Zebra chip is an increasingly serious disease in commercial potato production globally. Resistance can be pursued by control of the insect vector, the tomato-potato psyllid, Bactericera cockerelli or the bacterial causal agent, Candidatus Liberibacter olanacearum (Lso). Some Lso-infected plants of the wild potato species S. microdontum (mcd) had been observed to have low symptom xpression. Thus, we evaluated a representative core collection of 86 individuals from 50 mcd populations in the US Potato Genebank (USPG). Real-time quantitative PCR on tissue from infected leaves was used as a proxy for mean log titer (MLT) of Lso. Russet Burbank control had 56% of the MLT of the most susceptible mcd individual. The average for all mcd was 67%, and the lowest, most resistant six mcd individuals were 0%. Repeated testing of those six individuals identified two as most reliably resistant: mcd15B2 from PI 265575 and mcd62B1 from PI 498126. All of these mcd individuals are available from USPG. They should be useful for research and breeding aimed at better understanding and controlling Zebra chip disease.