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Comparative Histopathology of Host Reaction Types in Slash Pine Resistant to Cronartium quercuum f. sp. fusiforme
Executive Commission of the Plan for Cocoa Farming/Cocoa Research Center/Plant Pathology Department, km 22 Rod. Ilheus Itabuna 45600-970, Itabuna, Ba, Brazil
School of Forest Resources and Conservation, University of Florida, P.O. Box 110410, Gainesville, FL 32611-0410, USA
* Author to whom correspondence should be addressed.
Received: 23 January 2013; in revised form: 27 April 2013 / Accepted: 27 April 2013 / Published: 10 May 2013
Abstract: Histological examinations of the host reaction types (RTs); short galls, rough galls and smooth galls in slash pine seedlings inoculated with Cronartium quercuum f. sp. fusiforme revealed host reaction zone(s) [RZ(s)]. These RZs differed among the host RTs in location and pattern of occurrence in the stem, staining reaction, periderm formation and amount of fungal colonization. The RZ within short galls were wide, deep in the cortex, continuous around the stem, bordered on both sides by a well-developed periderm encircling the stem with limited fungal colonization. The RZ of the rough galls lacked a periderm, were small, numerous and discontinuous around the stem circumference, being separated by symptomatic tissue typical of a susceptible reaction. Fungal colonization of the rough galls was limited and hyphae and haustoria were encrusted. The RZ of the smooth galls were small and narrow conforming to the stem circumference, shallow in the cortex and interconnected by symptomatic tissues typical of a susceptible reaction. A narrow periderm developed along the innermost portion of the RZ in smooth galls and fungal colonization was abundant in the cortex. We suggest that the RTs large galls (rough and smooth), short galls, and hypersensitive-like stem lesions represent increasing resistance to the fusiform rust pathogen.
Keywords: defense mechanism; reaction types; reaction zones; disease resistance; Pinus elliottii var elliotii
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Gramacho, K.P.; Miller, T.; Schmidt, R.A. Comparative Histopathology of Host Reaction Types in Slash Pine Resistant to Cronartium quercuum f. sp. fusiforme. Forests 2013, 4, 319-328.
Gramacho KP, Miller T, Schmidt RA. Comparative Histopathology of Host Reaction Types in Slash Pine Resistant to Cronartium quercuum f. sp. fusiforme. Forests. 2013; 4(2):319-328.
Gramacho, Karina P.; Miller, Thomas; Schmidt, Robert A. 2013. "Comparative Histopathology of Host Reaction Types in Slash Pine Resistant to Cronartium quercuum f. sp. fusiforme." Forests 4, no. 2: 319-328.