Effects of light and the regulatory B-subunit composition of protein phosphatase 2A on the susceptibility of Arabidopsis thaliana to aphid (Myzus persicae) infestation

Abstract

The interactions between biotic and abiotic stress signaling pathways are complex and poorly understood but protein kinase/phosphatase cascades are potentially important components. Aphid fecundity and susceptibility to Pseudomonas syringae infection were determined in the low light-grown Arabidopsis thaliana wild type and in mutant lines defective in either the protein phosphatase (PP)2A regulatory subunit B'γ (gamma; pp2a-b'γ) or B'ζ (zeta; pp2a-b'ζ1-1 and pp2a-b'ζ 1-2) and in gamma zeta double mutants (pp2a-b'γζ) lacking both subunits. All the mutants except for pp2a-b'ζ 1-1 had significantly lower leaf areas than the wild type. Susceptibility to P. syringae was similar in all genotypes. In contrast, aphid fecundity was significantly decreased in the pp2a-b'γ mutant relative to the wild type but not in the pp2a-b'γζ double mutant. A high light pre-treatment, which led to a significant increase in rosette growth in all mutant lines but not in the wild type, led to a significant decrease in aphid fecundity in all genotypes. The high light pre-treatment abolished the differences in aphid resistance observed in the pp2a-b'γ mutant relative to the wild type. The light and CO2 response curves for photosynthesis were changed in response to the high light pre-treatment, but the high light effects were similar in all genotypes. These data demonstrate that a pre-exposure to high light and the composition of B-subunits on the trimeric PP2A holoenzymes are important in regulating plant resistance to aphids. The functional specificity for the individual regulatory B-subunits may therefore limit aphid colonization, depending on the prevailing abiotic stress environment.

Atypical Protein Phosphatase 2A Gene Families Do Not Expand via Paleopolyploidization

“…Likewise, mutations affecting members of the FASS/TON2 clade cause strong phenotypes due to defects in preprophase band formation (McClinton and Sung, 1997;Camilleri et al, 2002;Wright et al, 2009). Consistent with the functional specificity of plant PP2A B subunit isoforms, b5/b9g mutants have phenotypes distinct from b8/b9z mutants (Rasool et al, 2014;Konert et al, 2015). However, additional data suggest varying degrees of functional overlap among plant PP2A subunit isoforms.…”

Protein phosphatase 2A regulatory subunits affecting plant innate immunity, energy metabolism, and flowering time – joint functions among B'η subfamily members

“…10 The Arabidopsis B'g knockdown mutant showed constitutive induction of salicylic acid-and jasmonic aciddependent defense pathways, and the mutant was more resistant to bacterial, fungal, and aphid infections than wild type plants. 11,12 Moreover, B'g was proposed to have a role in daylength-dependent oxidative stress. 13 Another interesting study revealed a role for PP2A in negative regulation of PTI.…”

Cross-talk between high light stress and plant defence to the two-spotted spider mite in Arabidopsis thaliana

“…Therefore, photosynthetic machinery is a fine-tuneable mechanism whose functioning cannot be considered only in the context of plant productivity, as it seems to play a dominant role in the regulation of plant stress resistance Trotta et al 2014). Increasing evidence reinforces the profound effect of light on plant resistance/susceptibility to biotic stresses (Göhre et al 2012;Hua 2013;Rasool et al 2014;Roden and Ingle 2009;Szechyńska-Hebda et al 2010). This regulation is connected not only with light pre-treatment (Szechyńska-Hebda et al 2010), but is also dependent on the circadian clock (Bhardwaj et al 2011;Zhang et al 2013).…”

“…This response is accompanied by alterations in ROS and redox signals, and the induction of glutathione, salicylic acid (SA), and ethylene (ET) in both local and systemic leaves (Mühlenbock et al 2008;Szechyńska-Hebda et al 2010). Moreover, it was demonstrated that high-light pre-exposure caused enhanced resistance to aphid infestation in wild-type plants and in mutant lines defective in the composition of B-subunits on the trimeric protein phosphatase 2A (PP2A) holoenzymes (Rasool et al 2014).…”