Influence of Medium Calcium on Blackleg Severity in Potato Tissue Culture Plantlets

Tissue culture of potato has become an effective tool in the agricultural improvement of the plant. Meristem culture has successfully eliminated numerous potato viruses and resulted in the production of pathogen-free stock. Shoot-tip culture is widely used in research and the potato production industry for mass plant propagation and aseptic germplasm storage (23). Tissue culture can provide a unique system for studies on basic disease development, pathogen biology and host/pathogen interactions, as well. The aseptic conditions of tissue culture provide a [sic] environment where host/parasite relationships can be examined without the interaction of other microorganisms. In addition, media constituents can be manipulated to examine the effect of organic and/or inorganic nutrients on disease development in plantlets. Resistance of a plant to a pathogen is the result of several varying elements (ie., morphology, physiology, environment) and in vitro conditions may be favorable for the study of some of these components. Disease evaluation on tissue culture plantlets may not only increase the basic understanding of disease systems but may represent a step toward more efficient screening of plants for resistance to various pathogens. Time and space could be saved by utilizing in vitro techniques as compared to conventional disease resistance screening procedures conducted in the field or greenhouse. With the exception of certain viruses, disease reactions in potato tissue culture plantlets have not been examined. With the widespread use of tissue culture in both research and the potato production industry, information regarding disease development in plantlets would be valuable. The objectives of this study were to: 1): Examine the growth response of tissue culture plantlets of various potato cultivars grown on MS media modified to contain different levels of calcium. 2): Develop an in vitro inoculation technique to evaluate the development of blackleg on potato tissue culture plantlets. 3): Compare the in vitro disease reaction of potato tissue culture plantlets representing three levels of field resistance to blackleg when grown on two levels of medium calcium and inoculated with two isolates of Erwinia carotovora subspecies atroseptica