Pectin Methylesterases Modulate Plant Homogalacturonan Status in Defenses against the Aphid Myzus persicae

Abstract

Because they suck phloem sap and act as vectors for phytopathogenic viruses, aphids pose a threat to crop yields worldwide. Pectic homogalacturonan (HG) has been described as a defensive element for plants during infections with phytopathogens. However, its role during aphid infestation remains unexplored. Using immunofluorescence assays and biochemical approaches, the HG methylesterification status and associated modifying enzymes during the early stage of Arabidopsis (Arabidopsis thaliana) infestation with the green peach aphid (Myzus persicae) were analyzed. Additionally, the influence of pectin methylesterase (PME) activity on aphid settling and feeding behavior was evaluated by free choice assays and the Electrical Penetration Graph technique, respectively. Our results revealed that HG status and HG-modifying enzymes are significantly altered during the early stage of the plant-aphid interaction. Aphid infestation induced a significant increase in total PME activity and methanol emissions, concomitant with a decrease in the degree of HG methylesterification. Conversely, inhibition of PME activity led to a significant decrease in the settling and feeding preference of aphids. Furthermore, we demonstrate that the PME inhibitor AtPMEI13 has a defensive role during aphid infestation, since pmei13 mutants are significantly more susceptible to M. persicae in terms of settling preference, phloem access, and phloem sap drainage.

Aphid Transmission of Potyvirus: The Largest Plant-Infecting RNA Virus Genus

“…The electrical penetration graph (EPG) reads the electrical waveforms associated with aphid feeding and behavior. These include: non-probing (np), intracellular stylet puncture (pd), intercellular stylet pathway (C), salivation into phloem sieve elements (E1), and passive phloem sap uptake from phloem sieve elements (E2) [ 81 , 82 , 83 ]. Since potyvirus infection is not limited to any particular plant tissue [ 84 ], potyviruses appear to be most frequently acquired and inoculated during intracellular stylet puncture (pd) phase [ 81 , 85 ].…”

Differential Defense Responses of Upland and Lowland Switchgrass Cultivars to a Cereal Aphid Pest

“…Kanlow and Summer plants are important sources of genetics used for breeding to improved switchgrass cultivars adapted to the US Midwest [ 52 , 53 , 54 ]. Similar approaches have been used by other researchers to understand plant–aphid interactions [ 55 , 56 , 57 , 58 , 59 , 60 , 61 ]. As examples, Zhang et al [ 56 ] found that GB infestation of wheat increases endogenous reactive oxygen species (ROS) production compared to the non-phytotoxic aphid Sitobion avenae , suggesting a similarity in responses observed in Summer and hybrid switchgrass infested with GB or YSA [ 29 , 30 ].…”

Brassinosteroid signaling component SlBES1 promotes tomato fruit softening through transcriptional repression of PMEU1

“…The "egg box" signal was significantly elevated in SlBES1-RNAi and lowered in SlBES1-OX when compared with that in the wild type ( Figure 2D). Given the positive role of the "egg box" in cell wall strengthening (Senechal et al, 2014;Silva-Sanzana et al, 2019), the immunolocalization results suggested that decreased content of the "egg box" structure in SlBES1 fruit was the direct reason for SlBES1-induced fruit softening. Calcofluor-white staining showed no major differences in cell size or patterning between transgenic lines (Supplemental Figure S5).…”