Amero A. Emeran, and
First, second, and fourth authors: CSIC, Institute of Sustainable Agriculture, Apdo. 4084, E-14080 Córdoba, Spain; and third author: Department of Agricultural Botany, Faculty of Agriculture, Kafr El-Sheikh University, 33516 Kafr El-Sheikh, Egypt.
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Accepted for publication 24 October 2008.
Beet powdery mildew incited by Erysiphe betae is a serious foliar fungal disease of worldwide distribution causing losses of up to 30%. In the present work, we searched for resistance in a germplasm collection of 184 genotypes of Beta vulgaris including fodder (51 genotypes), garden (60 genotypes), leaf (51 genotypes), and sugar (22 genotypes) beet types. Resistant genotypes were identified in the four beet types under study. In addition, mechanisms underlying resistance were dissected through histological studies. These revealed different resistance mechanisms acting at different fungal developmental stages, i.e., penetration resistance, early and late cell death, or posthaustorial resistance. Most genotypes were able to hamper fungal development at several stages. The later are interesting for breeding aiming to resistance durability. Furthermore, characterization of defense mechanisms will be useful for further cellular and molecular studies to unravel the bases of resistance in this species.
Additional keywords:hypersensitive response, papilla, prepenetration resistance.
© 2009 The American Phytopathological Society