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Cytological and Molecular Analysis of the Hordeum vulgare-Puccinia triticina Nonhost Interaction

July 2003 , Volume 16 , Number  7
Pages  626 - 633

Christina Neu , Beat Keller , and Catherine Feuillet

Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland

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Accepted 20 February 2003.

Cultivated barley, Hordeum vulgare L., is considered to be a nonhost or intermediate host species for the wheat leaf rust fungus Puccinia triticina. Here, we have investigated, at the microscopic and molecular levels, the reaction of barley cultivars to wheat leaf rust infection. In the nonhost resistant cultivar Cebada Capa, abortion of fungal growth occurred at both pre- and posthaustorial stages, suggesting that defense genes are expressed throughout the development of the inappropriate fungus during the nonhost resistance reaction. In the two barley lines L94 and Bowman, a low level of prehaustorial resistance to P. triticina was observed and susceptibility was comparable to that of wheat control plants. Suppression subtractive hybridization was used to identify genes that are differentially expressed during the nonhost resistance reaction in Cebada Capa as well as during the successful establishment of the inappropriate wheat leaf rust fungus in L94. Northern analysis indicated that two candidate genes, including a barley ortholog of the rice resistance gene Xa21, are putatively involved in non-host and non-race-specific resistance reactions. In addition, a new gene that is specifically induced during the successful development of the inappropriate fungus P. triticina in barley has been identified.

Additional keywords: partial resistance, Puccinia hordei.

© 2003 The American Phytopathological Society