Fig. 1

Phytophthora palmivora exerts a hemibiotrophic lifestyle in Nicotiana benthamiana roots. a Representative pictures of root-infected plantlets during P. palmivora infection, showing disease progression on the aboveground tissues. The successive symptom extent stages (SESs) were used to define a disease index in order to quantitate disease progression over time. b–h Microscopic analysis of N. benthamiana roots inoculated with transgenic P. palmivora LILI expressing an endoplasmic reticulum (ER)-targeted yellow fluorescent protein (YFP). Pictures were taken during penetration (b, 3 h after inoculation (hai)), early infection (c, 6 hai), biotrophy (d, 18 hai and e, 24 hai), switch to necrotrophy (f, 30 hai) and necrotrophy (g, 48 hai and h, 72 hai). Each panel shows transmission light (Transmission) and merged YFP fluorescence with propidium iodide (PI) staining (YFP + PI). Hy hypha, Ve vesicle, Cy cyst, Ha haustorium. Scale bar is 10 μm. i Quantification of P. palmivora biomass accumulation over time in N. benthamiana roots was measured by expression of P. palmivora WS21 relative to N. benthamiana L23 and F-box reference genes. j, k Expression of P. palmivora lifestyle marker genes Hmp1 (j) and Cdc14 (k) were measured over time relative to P. palmivora WS21 and OPEL reference genes. Quantitative RT-PCR experiments were performed in triplicate. Circles represent values for each replicate. Bars represent the mean value. Statistical significance has been assessed using one-way analysis of variance (ANOVA) and Tukey’s honestly significant difference (HSD) test (p < 0.05)