|Munyaneza, Joseph - Joe
|Novy, Richard - Rich
|BESTER, GERHARD - Frito Lay Research
|BUCHMAN, JEREMY - Black Gold Farms
|NORDGAARD, JOHN - Black Gold Farms
|VAN HEST, PETER - Bejo Seeds
Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2015
Publication Date: 12/1/2015
Citation: Wallis, C.M., Munyaneza, J.E., Chen, J., Novy, R.G., Bester, G., Buchman, J.L., Nordgaard, J., Van Hest, P. 2015. 'Candidatus Liberibacter solanacearum' titers in and infection effects on potato tuber chemistry of promising germplasm exhibiting tolerance to zebra chip disease. Phytopathology. 105(12):1573-1584.
Interpretive Summary: Zebra chip disease (ZC) is a major threat to worldwide potato production. Development of potato germplasm with tolerance or resistance is key to sustainable and environmentally friendly management of ZC. Therefore, 283 potato breeding lines were screened for tolerance to infection by the ZC causal agent, ‘Candidatus Liberibacter solanacearum’ (Lso). Five potato breeding clones consistently did not exhibit fresh or fried ZC symptoms when infected with Lso and, therefore, were deemed tolerant. Compared to the susceptible variety ‘Atlantic’, these five breeding clones underwent significantly smaller shifts in host biochemistry upon Lso infection, which was consistent with the absence of ZC symptoms. The five tolerant potato clones will be used to develop commercially-viable varieties. Knowledge gained about tolerance mechanisms could be used to search for additional potato varieties that remain symptomless when Lso-infected.
Technical Abstract: Long-term sustainable management of zebra chip (ZC) disease of potato requires development of tolerant or resistant germplasm. To this end, 283 potato varieties and breeding clones were infected with the ZC putative causal agent ‘Candidatus Liberibacter solanacearum’ (Lso) by potato psyllid vector inoculations in 2010, 2011, 2012, and 2013. Potato germplasm was then examined for development of fresh and fried ZC symptoms. Over multiple years, 29 breeding clones exhibited little to no symptoms in freshly cut tuber slices, and five exhibited little to no symptoms in fried slices. These five presumed tolerant breeding clones were chosen for further screening to determine whether the lack of physiological responses to Lso infection was the cause of observed tolerance. To this end, tuber levels of amino acid, sugar, and phenolic were compared between non-infected and Lso-infected plants. The five putative tolerant clones had less dramatic shifts in host physiology following Lso infection compared to the susceptible cultivar Atlantic. Thus, lack of host response to Lso infection triggering major changes in tuber biochemistry may result in tolerance to ZC. As such, the lack of large-scale changes in host physiology following Lso infection is a trait that can be used to select ZC-tolerant potato varieties. These results also suggest that germplasm derived from relatives of cultivated potato plants are viable sources of ZC disease tolerance.