Comparisons of protein profiles of beech bark disease resistant and susceptible American beech (Fagus grandifolia)

Abstract

BackgroundBeech bark disease is an insect-fungus complex that damages and often kills American beech trees and has major ecological and economic impacts on forests of the northeastern United States and southeastern Canadian forests. The disease begins when exotic beech scale insects feed on the bark of trees, and is followed by infection of damaged bark tissues by one of the Neonectria species of fungi. Proteomic analysis was conducted of beech bark proteins from diseased trees and healthy trees in areas heavily infested with beech bark disease. All of the diseased trees had signs of Neonectria infection such as cankers or fruiting bodies. In previous tests reported elsewhere, all of the diseased trees were demonstrated to be susceptible to the scale insect and all of the healthy trees were demonstrated to be resistant to the scale insect. Sixteen trees were sampled from eight geographically isolated stands, the sample consisting of 10 healthy (scale-resistant) and 6 diseased/infested (scale-susceptible) trees.ResultsProteins were extracted from each tree and analysed in triplicate by isoelectric focusing followed by denaturing gel electrophoresis. Gels were stained and protein spots identified and intensity quantified, then a statistical model was fit to identify significant differences between trees. A subset of BBD differential proteins were analysed by mass spectrometry and matched to known protein sequences for identification. Identified proteins had homology to stress, insect, and pathogen related proteins in other plant systems. Protein spots significantly different in diseased and healthy trees having no stand or disease-by-stand interaction effects were identified.ConclusionsFurther study of these proteins should help to understand processes critical to resistance to beech bark disease and to develop biomarkers for use in tree breeding programs and for the selection of resistant trees prior to or in early stages of BBD development in stands. Early identification of resistant trees (prior to the full disease development in an area) will allow forest management through the removal of susceptible trees and their root-sprouts prior to the onset of disease, allowing management and mitigation of costs, economic impact, and impacts on ecological systems and services.

Impacts of Beech Bark Disease and Climate Change on American Beech

“…Allozyme analysis, haplotype analyses and proteomic studies have shown genetic variation among several tested populations [61][62][63]. Our laboratory has found genetic heterogeneity both among and between large tree stands in the Green and Adirondack Mountains through microsatellite analyses (Cohojari, O., Malik, E. and Coe, N., manuscript in preparation).…”

“…Information from microarray and proteomic comparative data sets will ideally move efforts for screening for resistance and restoring beech forests in light of stressors of BBD compounded by climate change forward. Two groups have put forth data to evaluate differential mRNA [76] and protein profiles [62] of bark from trees that are more or less susceptible to beech bark disease but the pace of this work has been limited by the lack of genomic and cDNA sequences widely available for American beech to date. Table 1.…”

“…Structural (endogenous to host) Stone cell layers of cortex may provide structural barrier(s) to scale stylet [80] Structural (exogenous to host) Forest type and forest dynamics [81] Forest structure [38] Species composition and site factors [82] Nutritional access (pathogen perspective) Nutrition partitioning allows tree to discourage infestation [40] Higher bark nitrogen may provide more desirable habitat for the beech scale [65,66] Nutritional availability (host perspective) Nutrients and water [26] Drought conditions [14] Differential gene expression Differential gene expression in disease resistant versus BBD-susceptible beech trees [62,76] Location attributes Stand-level [28] In considering the influence of climate change in synergy with disease pathology, it is necessary to consider all the environmental factors that may be influenced or linked to climate change within the context of both physical parameters (slope, aspect, etc.) and genetic conditions that may predispose trees to susceptibility or resistance.…”

Relation entre la composition foliaire et la présence de la maladie corticale du hêtre dans les stations du Réseau d’étude et de surveillance des écosystèmes forestiers du Québec

“…D'autres travaux indiquent que la composition de l'écorce en éléments nutritifs (en particulier, l'azote [N] et le phosphore [P]), en acides aminés et en composés phénoliques est associée à la prévalence de la maladie (Cale et al 2015). Des chercheurs ont aussi trouvé que la résistance à la MCH avait une base génétique (Mason et al 2013) et que celle-ci se transmettait aux descendants (Koch et al 2010). Ainsi, il est possible de réduire l'impact de la MCH par l'aménagement forestier en prélevant les individus affectés et les moins vigoureux (Leak 2006;Taylor et al 2013 …”

Mass Spectrometry and its Applications in Life Sciences

“…Third, proteomics is a mass spectrometrybased discipline; new and on the rise. [1][2][3][4][5][6] A PubMed search using the keywords mass spectrometry, mass spectrometry AND chemistry or proteomics clearly demonstrated the importance of mass spectrometry in chemical research, as well as the establishment of proteomics as a rather mature discipline (Fig. 1).…”