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Identification of Brassica accessions resistant to ‘old’ and ‘new’ pathotypes of Plasmodiophora brassicae from Canada
Author(s) -
FreduaAgyeman R.,
Hwang S. F.,
Strelkov S. E.,
Zhou Q.,
Manolii V. P.,
Feindel D.
Publication year - 2019
Publication title -
plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.928
H-Index - 85
eISSN - 1365-3059
pISSN - 0032-0862
DOI - 10.1111/ppa.12980
Subject(s) - clubroot , biology , brassica rapa , brassica , canola , brassica oleracea , spore , brassicaceae , botany , horticulture
Genetic resistance is the main tool used to manage clubroot of canola ( Brassica napus ) in Canada. However, the emergence of new virulent strains of the clubroot pathogen, Plasmodiophora brassicae , has complicated canola breeding efforts. In this study, 386 Brassica accessions were screened against five single‐spore isolates (represented by pathotypes 2F, 3H, 5I, 6M and 8N on the Canadian Clubroot Differential Set) and 17 field isolates (represented by 12 unique pathotypes: 2B, 3A, 3D, 3O, 5C, 5G, 5K, 5L, 5X, 8E, 8J and 8P) of P. brassicae to identify resistance sources effective against these strains. The results showed that one B. rapa accession ( CDCNFG ‐046, mean index of disease ( ID ) = 3.3%) and two B. nigra accessions ( CDCNFG ‐263, mean ID = 3.1%; and CDCNFG ‐262, mean ID = 4.7%) possessed excellent resistance to all 22 of the isolates evaluated. Fifty other accessions showed differential clubroot reactions (resistant, moderately resistant or susceptible), including 27 (one B. napus , two B. rapa , four B. oleracea and 20 B. nigra ) accessions that were each resistant to 8–21 P. brassicae isolates, but developed mean ID s in the range of 5.3–29.6%. The remaining 23 accessions (two B. napus , one B . rapa , five B . oleracea and 15 B. nigra ) were each resistant to 3–13 isolates, but developed mean ID s in the range of 30.3–47.0%. The three accessions that showed absolute resistance and the 50 accessions that showed differential clubroot reactions could be used to breed for resistance to the new P. brassicae strains.