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United States Department of Agriculture

Agricultural Research Service

Research Project: POTATO GENETICS, CYTOGENETICS, DISEASE RESISTANCE, AND PRE-BREEDING UTILIZING WILD AND CULTIVATED SPECIES Title: Suppression of defense response in a potato clone with tolerance to Verticillium dahliae

Authors
item Tai, Helen -
item Goyer, Claudia -
item Platt, H -
item DE Koeyer, David -
item Murphy, Agnes -
item Uribe, Pedro -
item Halterman, Dennis

Submitted to: Functional and Integrative Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 11, 2013
Publication Date: N/A

Interpretive Summary: Verticillium wilt of potato is a widespread disease that results in yield loss. It is a soil-borne pathogen that is difficult to control. Very little resistance to the disease is present within cultivated potato varieties. Therefore, control of the disease is currently reliant on the application of fumigants before planting, which is costly and environmentally unfriendly. It is important when breeding to differentiate true resistance to the pathogen (no reproduction) to tolerance (no disease symptoms but the pathogen can reproduce). Tolerance is undesirable in new cultivars because the amount of pathogen can increase in infected fields. We have identified two individual potato plants from the same population that exhibit either tolerance or resistance. We found that differences in the reaction to Verticillium in these two plants is due to changes in the expression of genes that are involved in pathogen defense responses. Importantly, we have identified key regulators of this response that could be used in breeding for increased resistance. The results of this work will impact the development of Verticillium resistant cultivars by not only providing resistant parental germplasm but also through the identification of key regulators in defense responses.

Technical Abstract: Verticillium dahliae Kleb. is a soil-borne fungi that colonizes vascular tissues and induces early senescence in potato in a disease called Verticillium wilt. A diploid potato clone, 07506-01, was infected at high levels with V. dahliae but did not develop symptoms, indicating tolerance to the pathogen. Tolerance was not associated with the Ve2 resistance gene as 07506-01 was found to carry susceptible alleles. 07506-01 was compared to another diploid clone, 12120-03 which carried the Ve2 resistance allele, using gene expression profiling with the Potato Oligonucleotide Chip Initiative (POCI) microrarray. The results demonstrated that infection with V. dahliae affected 07506-01 and 12120-03 in different ways. Growth and photosynthesis were maintained at higher levels in the tolerant 07506-01 compared to 12120-03 and there was evidence for suppression of defense responses in the former clone. Expression of Ve resistance genes and defense phytohormone biosynthetic enzyme genes was found to be decreased in 07506-01 compared to 12120-03. Transcription factor gene expression differences pointed to the WRKY family of transcription factors as regulators of V. dahliae responses in potato.

Last Modified: 11/23/2014
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