Analyses of bark proteins in blister rust-resistant and susceptible western white pine (Pinus monticola)

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dc.contributor.authorDavidson, Joanne Jeanen_US
dc.date.accessioned2024-08-13T20:15:47Z
dc.date.available2024-08-13T20:15:47Z
dc.date.copyright1994en_US
dc.date.issued1994
dc.degree.departmentDepartment of Biology
dc.degree.levelMaster of Science M.Sc.en
dc.description.abstractThis study was undertaken to determine whether significant differences exist in the bark protein profiles of phenotypically blister rust-resistant and susceptible Pinus monticola. White pine blister rust is a devastating disease of 5-needle pines caused by the recently introduced (early 20th century) fungal pathogen, Cronartium ribicola. Several resistance mechanisms have been identified in both foliage and stem tissue and although most of these resistance mechanisms have been shown to be under oligogenic or polygenic control, little else is known of their physiological and/or biochemical nature. Because no biochemical 'resistance' markers are available to use in early progeny screenings, the selection and testing processes involved in the breeding of rust resistant pine are costly in terms of time and labour. Predicting which trees will survive rust infection 'in the field' remains one of the challenges of white pine breeders. Identification of significant quantitative or qualitative protein differences between blister rust resistant and susceptible groups is an important first step in the isolation and functional characterization of potential resistance markers. The bark reaction known as 'slow canker growth' (SCG) was selected for study because of its delayed onset and because seedlings displaying this reaction tend to survive well in the field. In addition 'mature tree resistance' in well characterized clones was also studied. Individually extracted bark proteins from a total of 16 trees were separated by SDS-PAGE and two-dimensional (2-D) gel electrophoresis. After silver staining, gels were scanned and analyzed with the aid of a laser scanner interfaced with one and two-dimensional software. SDS-PAGE separated and electroblotted proteins were further characterized by immunodetection with barley and petunia anti-chitinase polyclonal antibodies and antibodies raised against a white pine photosystem II protein (PSII) and cold hardiness-related protein (Pin m III). Two-dimensional gel electrophoresis demonstrated multiple qualitative and quantitative protein differences between resistant and susceptible groups. Generally, susceptible groups had more unique and quantitatively increased proteins than resistant groups. The most dramatic and consistent differences were seen between resistant ('SCG') versus susceptible seedlings, while trees displaying 'mature tree resistance' had fewer significant changes. Immunodetection with anti-chitinase polyclonal antibodies revealed several bands between 28 kDa and 35 kDa. Qualitative band differences were noted between resistant and susceptible half-siblings (seedlings) but were not consistent for all families tested. Chitinase activity was also detected in mature, lyophilized bark extracts using a 2-step colourimetric assay which employed N-acetyl-glucosaminidase as the second enzyme. Immunodetection with anti-PinmIII demonstrated that susceptible mature trees were selectively enriched in a 19.2 kDa protein. Three significant bands were isolated and characterized by N-terrninal amino acid sequencing; a 10.6 kDa band shown to be selectively enriched in resistant (SCG) seedlings from 4 families tested, the 19.2 kDa band selectively enriched in mature susceptible trees, and a 26.2 kDa band found to be enriched near the canker tissue of a susceptible seedling. The latter band may correspond to a unique 26.0 kDa immunoreactive (anti-chitinase) band seen in the same individual tree. The significance of these findings is discussed.en
dc.format.extent81 pages
dc.identifier.urihttps://hdl.handle.net/1828/17605
dc.rightsAvailable to the World Wide Weben_US
dc.titleAnalyses of bark proteins in blister rust-resistant and susceptible western white pine (Pinus monticola)en_US
dc.typeThesisen_US

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