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United States Department of Agriculture

Agricultural Research Service


Location: Vegetable Crops Research

Title: Effect of Alternaria solani exudates on resistant and susceptible potato cultivars from two different pathogen isolates

item Shahbazi, Hadis
item Aminian, Heshmatollah
item Sahebani, Navazollah
item Halterman, Dennis

Submitted to: Plant Pathology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2010
Publication Date: 2/15/2011
Citation: Shahbazi, H., Aminian, H., Sahebani, N., Halterman, D.A. 2011. Effect of Alternaria solani exudates on resistant and susceptible potato cultivars from two different pathogen isolates. Plant Pathology Journal . 27(1):14-19.

Interpretive Summary: We have previously identified potato cultivars that differ significantly in resistance to the early blight pathogen Alternaria solani. Here, we found that different isolates of the pathogen are able to cause different symptoms based solely on the phytotoxins that they produce. Both detached leaves and whole in vitro plantlets were exposed to a sterilized solution taken from liquid-grown A. solani cultures. The solution from the more aggressive pathogen isolate caused more symptoms on potato than the less aggressive isolate, suggesting a difference in the amount of strength of the toxins produced. Our findings will impact potato breeders by providing methodologies that can be used to screen and select germplasm containing resistance to Alternaria solani.

Technical Abstract: The resistance phenotypes of two potato cultivars to two isolates of Alternaria solani, causal agent of early blight, were studied under greenhouse conditions. The two isolates contain varying degrees of aggressiveness on both susceptible and resistant phenotypes of potatoes. A bioassay was used to study the role of liquid culture exudates produced in vitro in pathogenicity and elicitation of disease symptomology in seedlings as well as detached leaves. Responses of host genotypes to the exudates of the two A. solani isolates were significantly different. Interestingly, the phytotoxicity effect of the culture filtrate from the more aggressive isolate A was higher than from isolate N suggesting an increased concentration or strength of the toxins produced. Furthermore, the resistant cultivar ‘Diamond’ elicited fewer symptoms to each isolate when compared to the susceptible cultivar ‘Granula’.

Last Modified: 10/16/2017
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