FIG 4 .

Phytophthora infestans RXLR effector 22926 (Pi22926) is secreted from mycelium in vitro and localizes to haustoria during infection. (A) Expression of the Pi22926-monomeric red fluorescent protein (mRFP) fusion protein was confirmed using an mRFP antibody. Fusion protein was detected in in vitro-grown mycelium (M) and was IP from infected tissue by P. infestans transformants constitutively expressing Pi22926-mRFP fusions. Green fluorescent protein antibody (αGFP) was used as a cytoplasmic marker as described for Fig. 2. Size markers are indicated in kilodaltons, and protein loading is indicated by Ponceau staining (PS). (B) Confocal projection of intercellular hyphae and haustoria of the Pi22926-mRFP transformant in infected N. benthamiana leaf tissue, showing that the fusion protein was present at haustoria. The white arrow indicates the path used for the fluorescence intensity profile of mRFP and GFP fluorophores across the haustorium. The profile is shown at the right of the images. The x-axis data in the graphs represent the distance (in micrometers) from one end of the white arrow to the other end. Scale bar represents 10 µm.