Infection of Arabidopsis thaliana by Phytophthora parasitica and identification of variation in host specificity

Abstract

Oomycete pathogens cause severe damage to a wide range of agriculturally important crops and natural ecosystems. They represent a unique group of plant pathogens that are evolutionarily distant from true fungi. In this study, we established a new plant-oomycete pathosystem in which the broad host range pathogen Phytophthora parasitica was demonstrated to be capable of interacting compatibly with the model plant Arabidopsis thaliana. Water-soaked lesions developed on leaves within 3 days and numerous sporangia formed within 5 days post-inoculation of P. parasitica zoospores. Cytological characterization showed that P. parasitica developed appressoria-like swellings and penetrated epidermal cells directly and preferably at the junction between anticlinal host cell walls. Multiple haustoria-like structures formed in both epidermal cells and mesophyll cells 1 day post-inoculation of zoospores. Pathogenicity assays of 25 A. thaliana ecotypes with six P. parasitica strains indicated the presence of a natural variation in host specificity between A. thaliana and P. parasitica. Most ecotypes were highly susceptible to P. parasitica strains Pp014, Pp016 and Pp025, but resistant to strains Pp008 and Pp009, with the frequent appearance of cell wall deposition and active defence response-based cell necrosis. Gene expression and comparative transcriptomic analysis further confirmed the compatible interaction by the identification of up-regulated genes in A. thaliana which were characteristic of biotic stress. The established A. thaliana-P. parasitica pathosystem expands the model systems investigating oomycete-plant interactions, and will facilitate a full understanding of Phytophthora biology and pathology.

Pathogen-associated molecular pattern-triggered immunity and resistance to the root pathogen Phytophthora parasitica in Arabidopsis

“…Most of these lines, including Ws-4, did not show necrosis after CBEL treatment. While Arabidopsis natural variability of resistance to bacterial and fungal pathogens has been documented for some pathogens including Phytophthora (Denby et al , 2004; Birker et al , 2009; Attard et al , 2010; Nemri et al , 2010; Wang et al , 2011), natural variability to necrotic elicitors has not been explored. The current results suggest that necrotic response to CBEL cannot be generalized to the A. thaliana species.…”

Phenotypic Analyses of Arabidopsis T-DNA Insertion Lines and Expression Profiling Reveal That Multiple L-Type Lectin Receptor Kinases Are Involved in Plant Immunity

“…Bacteria usually penetrate via natural opening such as stomata, and stomatal closure can essentially restrict bacterial invasion (Melotto et al 2006). Phytophthora pathogens can also penetrate via stomata but, instead, they prefer to penetrate at the junctions between epidermal cells (Hardham 2007;Wang et al 2011). Therefore, the function of LecRK-V.5 in suppressing stomatal immunity is dispensable for preventing Phytophthora penetration.…”

“…To determine the involvement of other LecRK in Phytophthora resistance, we performed infection assays on the LecRK T-DNA insertion lines with P. brassicae, P. capsici, and P. parasitica. Recently it was reported that the latter two are able to infect Arabidopsis (Wang et al 2011(Wang et al , 2013.…”

Invasive cells in animals and plants: searching for LECA machineries in later eukaryotic life

“…For instance, penetration of host tissues by Phytophtora sp . has been only recently characterized morphologically, and very little is known about the underlying molecular mechanisms [5,6]. …”

“…Furthermore, these myosins contribute to developmentally regulated organization of the F-actin bundles in the growing root hairs; in some multiple knockouts of myosin genes, the depolarization/branching defects (analogous to those seen when AtFH8 is up-regulated) were described [4]. Given that several plant myosins are expressed specifically in pollen [6], it seems likely that the myosins are indispensible for pollen tube growth as well. Although polar growth of the budding yeast cells cannot be considered invasive, it also relies on myosin V closely related to plant myosins XI [7].…”