Elevated CO2 reduces disease incidence and severity of a red maple fungal pathogen via changes in host physiology and leaf chemistry

Mcelrone, A. J. and Reid, C. D. and Hoye, K. A. and et al, . (2005) Elevated CO2 reduces disease incidence and severity of a red maple fungal pathogen via changes in host physiology and leaf chemistry. Global Change Biology, 11. pp. 1828-1836.

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Atmospheric CO2 concentrations are predicted to double within the next century. Despite this trend, the extent and mechanisms through which elevated CO2 affects plant diseases remain uncertain. In this study, we assessed how elevated CO2 affects a foliar fungal pathogen, Phyllosticta minima, of Acer rubrum growing in the understory at the Duke Forest free-air CO2 enrichment experiment in Durham, North Carolina. Surveys of A. rubrum saplings in the 6th, 7th, and 8th years of the CO2 exposure revealed that elevated CO2 significantly reduced disease incidence, with 22%, 27%, and 8% fewer saplings and 14%, 4%, and 5% fewer leaves infected per plant in the three consecutive years, respectively. Elevated CO2 also significantly reduced disease severity in infected plants in all years (e.g. mean lesion area reduced 35%, 50%, and 10% in 2002, 2003, and 2004, respectively). To assess the mechanisms underlying these changes, we combined leaf structural, physiological and chemical analyses with growth chamber studies of P. minima growth and host infection. In vitro exponential growth rates of P. minima were enhanced by 17% under elevated CO2, discounting the possibility that disease reductions were because of direct negative effects of elevated CO2 on fungal performance. Scanning electron micrographs (SEM) verified that conidia germ tubes of P. minima infect A. rubrum leaves by entering through the stomata. While stomatal size and density were unchanged, stomatal conductance was reduced by 21–36% under elevated CO2, providing smaller openings for infecting germ tubes.

Item Type: Article
Additional Information: This research was supported by the US Department of Energy’s Office of Science (BER), Grant No. DE-FG02-95ER62083. Thanks to R. N. Addington, T. Crocker, C. W. Cook, B. McElrone, and H. Strong for help in image collection and analysis, to E. DeLucia, R. Knepp, and D. Moore for sharing preliminary images and discussing possible pathosystems, to J. Mohan for providing access to subplots, to L. M. Eibest for training and assistance in Duke’s Biological Sciences Scanning Electron Microscope Facility, and to G. Abad at the Plant Pathogen Identification Laboratory at North Carolina State University for initial P. minima isolation and identification. Undergraduate research grants supported KAH (Duke Biology and the Visible Thinking Program at Duke) and EH (The Department of Energy’s SURE program).
Uncontrolled Keywords: climate change, Duke FACE, elevated CO2, fungal plant pathogen, free-air CO2 enrichment, plant disease, plant–pathogen interactions, red maple
Author Affiliation: Department of Biology, Duke University, Durham, NC 27708, USA
Subjects: Plant Protection
Divisions: General
Depositing User: Mr Siva Shankar
Date Deposited: 21 Jun 2012 11:29
Last Modified: 21 Jun 2012 11:30
Official URL: http://dx.doi.org/10.1111/j.1365-2486.2005.01015.x
URI: http://eprints.icrisat.ac.in/id/eprint/6169

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