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Comparative analysis of early H 2 O 2 accumulation in compatible and incompatible wheat–powdery mildew interactions
Author(s) -
Li A. L.,
Wang M. L.,
Zhou R. H.,
Kong X. Y.,
Huo N. X.,
Wang W. S.,
Jia J. Z.
Publication year - 2005
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/j.1365-3059.2005.01173.x
Subject(s) - powdery mildew , blumeria graminis , biology , germ tube , botany , inoculation , basidiomycota , cell culture , microbiology and biotechnology , plant disease resistance , genetics , horticulture , spore , gene
Comparative analysis was carried out for hydrogen peroxide (H 2 O 2 ) accumulation in response to powdery mildew ( Blumeria graminis [ Erysiphe graminis ] f.sp. tritici ) primary germ tube (PGT) and appressorial germ tube (AGT) contact, and in papilla (cell wall apposition) and hypersensitive responses (HR) in wheat ( Triticum aestivum ). Using primary leaves of three susceptible wheat lines (Bainong 3217; Beijing 837; Jingshuang 16) and five resistant lines [Mardler ( Pm2 + Pm6 ); Ulka/8 × Cc ( Pm2 ); Mardler/7 × Bainong 3217 ( Pm2 ); Pm16; Pm16/7 × Beijing 837 ( Pm16 )], early H 2 O 2 accumulation between 10 and 48 h after inoculation was studied. Strong H 2 O 2 accumulation was found in effective papillae and associated cytosolic vesicles in both susceptible and resistant wheat lines, suggesting the important role of H 2 O 2 in effective papillae formed as a general plant defence against powdery mildew. High frequency of effective papilla formation was observed in all five resistant lines. Among resistant lines, hypersensitive cell death was detected earlier in Mardler and Ulka/8 × Cc than in Pm16 and Pm16/7 × Beijing 837. In all cases this was associated with H 2 O 2 accumulation in attacked epidermal cells. Interestingly, penetration resistance but not HR appeared to be mediated by the Pm2 gene in the Mardler/7 × Bainong 3217 line, suggesting that Pm2 may govern an HR‐independent defence pathway in this genetic background. As effective papillae and HR did not occur in the same cells, papilla deposition may be independent of the HR response, despite the fact that both defence mechanisms were associated with high H 2 O 2 accumulation. In wheat powdery mildew‐incompatible interactions, HR acts as a second line of defence to contain infection when the papilla defence fails.