Infection of a tomato cell culture by Phytophthora infestans; a versatile tool to study Phytophthora-host interactions

Abstract

BackgroundThe oomycete Phytophthora infestans causes late blight on potato and tomato. Despite extensive research, the P. infestans-host interaction is still poorly understood. To find new ways to further unravel this interaction we established a new infection system using MsK8 tomato cells. These cells grow in suspension and can be maintained as a stable cell line that is representative for tomato.ResultsMsK8 cells can host several Phytophthora species pathogenic on tomato. Species not pathogenic on tomato could not infect. Microscopy revealed that 16 h after inoculation up to 36% of the cells were infected. The majority were penetrated by a germ tube emerging from a cyst (i.e. primary infection) while other cells were already showing secondary infections including haustoria. In incompatible interactions, MsK8 cells showed defense responses, namely reactive oxygen species production and cell death leading to a halt in pathogen spread at the single cell level. In compatible interactions, several P. infestans genes, including RXLR effector genes, were expressed and in both, compatible and incompatible interactions tomato genes involved in defense were differentially expressed.ConclusionsOur results show that P. infestans can prosper as a pathogen in MsK8 cells; it not only infects, but also makes haustoria and sporulates, and it receives signals that activate gene expression. Moreover, MsK8 cells have the ability to support pathogen growth but also to defend themselves against infection in a similar way as whole plants. An advantage of MsK8 cells compared to leaves is the more synchronized infection, as all cells have an equal chance of being infected. Moreover, analyses and sampling of infected tissue can be performed in a non-destructive manner from early time points of infection onwards and as such the MsK8 infection system offers a potential platform for large-scale omics studies and activity screenings of inhibitory compounds.Electronic supplementary materialThe online version of this article (doi:10.1186/s13007-017-0240-0) contains supplementary material, which is available to authorized users.

Comparative Transcriptome Analysis between a Resistant and a Susceptible Wild Tomato Accession in Response to Phytophthora parasitica

“…In P. parasitica treated samples, 18 genes were found highly upregulated in Sp-S and comparatively less induced in Sp-R at both 24 and 48 hpi. 14 out of these 18 were very important plant defense regulators including 5 pathogenesis related proteins (Solyc09g007010.1, Solyc04g064880.2, Solyc01g106620.2, Solyc01g097270.2 and Solyc01g097240.2), two chitinases CHI3 (Solyc02g082920.2), CHI-B (Solyc10g055800.1), LOX1 (Solyc08g029000.2), MLP423 (Solyc09g090980.2) and BG1 (Solyc10g079860.1) [15,16,17,18]. Another important plant defense gene, rubisco activase (Solyc10g086580.1) was expressed in both Sp-R and Sp-S P. parasitica treated plants only at 48 hpi [19].…”

Devastating intimacy: the cell biology of plant–Phytophthora interactions

“…Nuclei have been observed to locate adjacent to haustoria in the early stages of cell infection (e.g. Schoina et al ., 2017; Fig. 5a,b).…”

Expression profiling across wild and cultivated tomatoes supports the relevance of early miR482/2118 suppression for Phytophthora resistance

“…However, the number of all infection structures was lower in S. arcanum compared with the other two species ( figure 4 e ). As less virulent isolates of P. infestans also show a reduction in haustoria compared with more virulent isolates [ 49 ], this suggests that P. infestans is less infective and has a delayed life cycle transition on S. arcanum .

Figure 4.

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