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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: Molecular Interactions Determining Rpi-blb1 Mediated Late Blight Resistance

item Halterman, Dennis

Submitted to: European Association for Potato Research
Publication Type: Abstract Only
Publication Acceptance Date: May 14, 2010
Publication Date: June 28, 2010
Citation: Halterman, D.A. 2010. Molecular Interactions Determining Rpi-blb1 Mediated Late Blight Resistance [abstract]. European Association for Potato Research. p. 40.

Technical Abstract: The potato late blight resistance (R) gene Rpi-blb1 belongs to the valuable class of plant R genes that confer resistance to a broad spectrum of pathogen isolates. Rpi-blb1 protein recognizes the presence of members of the Phytophthora infestans effector family IPI-O to elicit resistance. We have studied IpiO diversity from 40 different P. infestans isolates collected from Guatemala, Thailand, and the United States. We have found that all of the isolates contain IPI-O variants that can be recognized by Rpi-blb1. However, some of these isolates contain an extraordinarily large number of variants. A few isolates also contain an IPI-O variant (IPI-O4) that is not recognized by Rpi-blb1. Isolates containing IPI-O4 are able to overcome resistance in Rpi-blb1-containing potato leaves to cause significantly more disease than isolates that do not contain IPI-O4, even when other IPI-O proteins are present. We show that the presence of IPI-O4 blocks the ability of Rpi-blb1 to recognize the presence of other IPI-O variants through direct interaction with the resistance protein, thereby preventing programmed cell death related to the resistance response.

Last Modified: 8/24/2016
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