Photosynthetic and respiratory changes in leaves of poplar elicited by rust infection. Photosynth Res

Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, Stn. Sainte-Foy, Quebec, QC, Canada.
Photosynthesis Research (Impact Factor: 3.5). 12/2009; 104(1):41-8. DOI: 10.1007/s11120-009-9507-2
Source: PubMed


Poplars are challenged by a wide range of pathogens during their lifespan, and have an innate immunity system that activates defence responses to restrict pathogen growth. Large-scale expression studies of poplar-rust interactions have shown concerted transcriptional changes during defence responses, as in other plant pathosystems. Detailed analysis of expression profiles of metabolic pathways in these studies indicates that photosynthesis and respiration are also important components of the poplar response to rust infection. This is consistent with our current understanding of plant pathogen interactions as defence responses impose substantive demands for resources and energy that are met by reorganization of primary metabolism. This review applies the results of poplar transcriptome analyses to current research describing how plants divert energy from plant primary metabolism for resistance mechanisms.

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    • "During susceptible responses, poplar genes associated with photosynthesis were downregulated while genes associated with carbon metabolism and respiration were upregulated 6 to 9 d after initial attack (Miranda et al. 2007, Azaiez et al. 2009). In susceptible plants, downregulation of photosynthesis has been proposed as a plant strategy to favor processes like respiration over assimilatory metabolic processes to generate defense resources (Major et al. 2010), whereas in resistant plants, the upregulation of various genes associated with photosynthesis has been proposed to supply the carbon skeletons, energy, and reducing equivalents needed to mount defenses against invaders. As the leaf tissue sampled for these investigations with poplar trees was located near (on the same leaf) infection sites, these results would be most comparable with our results for leaf three (the directly attacked leaf), which showed a slight increases of photosynthesis for both resistant and susceptible Hessian fly-attacked plants. "
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    ABSTRACT: Gall-inducing insects are known for altering source-sink relationships within plants. Changes in photosynthesis may contribute to this phenomenon. We investigated photosynthetic responses in wheat [Triticum aestivum L. (Poaceae: Triticeae)] seedlings attacked by the Hessian fly [Mayetiola destructor (Say) (Diptera: Cecidomyiidae], which uses a salivary effector-based strategy to induce a gall nutritive tissue in susceptible plants. Resistant plants have surveillance systems mediated by products of Resistance (R) genes. Detection of a specific salivary effector triggers downstream responses that result in a resistance that kills neonate larvae. A 2 × 2 factorial design was used to study maximum leaf photosynthetic assimilation and stomatal conductance rates. The plant treatments were-resistant or susceptible wheat lines expressing or not expressing the H13 resistance gene. The insect treatments were-no attack (control) or attack by larvae killed by H13 gene-mediated resistance. Photosynthesis was measured for the second and third leaves of the seedling, the latter being the only leaf directly attacked by larvae. We predicted effector-based attack would trigger increases in photosynthetic rates in susceptible but not resistant plants. For susceptible plants, attack was associated with increases (relative to controls) in photosynthesis for the third but not the second leaf. For resistant plants, attack was associated with increases in photosynthesis for both the second and third leaves. Mechanisms underlying the increases appeared to differ. Resistant plants exhibited responses suggesting altered source-sink relationships. Susceptible plants exhibited responses suggesting a mechanism other than altered source-sink relationships, possibly changes in water relations that contributed to increased stomatal conductance.
    Environmental Entomology 06/2015; 44(3). DOI:10.1093/ee/nvv028 · 1.30 Impact Factor
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    • "This suggests that the reduction in net assimilation rate in E. alphitoides infected Q. robur leaves was associated with reductions in the amount and/or activity of rate-limiting proteins such as ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Impairment of stomatal conductance and photosynthesis and resulting enhanced water loss in infected plants have also been observed in other studies (Robert et al. 2005, Major et al. 2009). In addition, despite the parallel reductions in net assimilation rate and stomatal conductance in downy mildew Peronospora plantaginis-infected Plantago ovata leaves, intercellular CO 2 concentration actually increased in infected leaves, also indicating that the demand for CO 2 decreased relatively more than the supply of CO 2 (Mandal et al. 2009). "
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    ABSTRACT: Oak powdery mildew (Erysiphe alphitoides) is a major foliar pathogen of Quercus robur often infecting entire tree stands. In this study, foliage photosynthetic characteristics and constitutive and induced volatile emissions were studied in Q. robur leaves, in order to determine whether the changes in foliage physiological traits are quantitatively associated with the degree of leaf infection, and whether infection changes the light responses of physiological traits. Infection by E. alphitoides reduced net assimilation rate by 3.5-fold and isoprene emission rate by 2.4-fold, and increased stomatal conductance by 1.6-fold in leaves with the largest degree of infection of ∼60%. These alterations in physiological activity were quantitatively associated with the fraction of leaf area infected. In addition, light saturation of net assimilation and isoprene emission was reached at lower light intensity in infected leaves, and infection also reduced the initial quantum yield of isoprene emission. Infection-induced emissions of lipoxygenase pathway volatiles and monoterpenes were light-dependent and scaled positively with the degree of infection. Overall, this study indicates that the reduction of foliage photosynthetic activity and constitutive emissions and the onset of stress volatile emissions scale with the degree of infection, but also that the infection modifies the light responses of foliage physiological activities. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email:
    Tree Physiology 11/2014; 34(12):1399-1410. DOI:10.1093/treephys/tpu091 · 3.66 Impact Factor
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    • "As expected, due to overexpression of Rubisco activase, the Rubisco itself (spots 26, 32 and 101) was up-regulated after 48 post inoculation. As previously mentioned, the defense mechanisms demand for assimilates, carbon skeletons and require energy to synthesize primary and secondary defensive compounds [35] [36] [37]. The involvement of the photosynthetic process during disease resistance has been previously noted in the incompatible Fig. 5. Modulation of hydrogen peroxide (H2O2) in cowpea leaves after inoculation with C. gloeosporioides. "
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    Plant Science 03/2014; DOI:10.1016/j.plantsci.2013.12.010 · 3.61 Impact Factor
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