Figure 5

Classification system for the extent of wall ingrowth deposition in PP TCs in minor veins of Arabidopsis leaves. A. Class I - no wall ingrowths visible in PP cells (asterisks), which are identified by their sharing a common wall with a large bundle sheath cell. B. Class II - evidence of discrete, punctate-like wall ingrowth deposition seen as discrete fluorescent dots (arrows) distributed along the face of PP TCs adjacent to either a CC or SE. Not all PP cells in a given field of view contain wall ingrowths. C. Class III - substantial levels of reticulate wall ingrowth deposition is seen as clusters or continuous stretches of fluorescent labelling (arrows) on the face of PP TCs (asterisks) neighboring cells of the SE/CC complex. This level of labelling is seen in most PP cells in a given field of view, but can be somewhat variable. D. Class IV - extensive wall ingrowth deposition seen as thick bands of fluorescence labelling (arrows) seen in essentially all PP TCs in a given field of view. BS, bundle sheath cell; CC, companion cell; SE, sieve element. Scale bars = 10 μm in A, B, C and D.