Fig. 5: Phloem-limitation enabled by PEN3 favors acquisition of the virus by the insect vector.
From: Defence-mediated phloem restriction of a plant virus facilitates insect transmission
a Viral symptom induced by TbCSV(Y35), TbCSV(Y41) and TbCSV(Y35-2C4) in wild-type (WT) and slpen3 knock-out tomato plants at 30 days post-inoculation (dpi). Two independent slpen3 knock-out tomato plants and yellowing symptoms in the leaf lamina of WT and slpen3 tomato plants are shown. Photographs were taken at 30 dpi. b Immunofluorescence detection of TbCSV in sections of WT and slpen3 knock-out tomato plants infected by TbCSV(Y35), TbCSV(Y41), or TbCSV(Y35-2C4). The distribution of TbCSV(Y35), TbCSV(Y41), or TbCSV(Y35-2C4) was visualized in a cross-section of leaf vein tissues using an antibody against the TbCSV coat protein (CP) (red). Autofluorescence of highly lignified tissues is shown in blue. PC, parenchyma; P, phloem; X, xylem. White arrowheads indicate TbCSV in parenchyma cells. Scale bar = 50 μm. c Immunofluorescence detection of TbCSV in midguts of Zhejiang II whiteflies after feeding on WT or slpen3 knock-out tomato plants infected by TbCSV(Y35), TbCSV(Y41) or TbCSV(Y35-2C4). TbCSV was detected using a monoclonal antibody against the TbCSV coat protein (CP), followed by a commercial 549-conjugated secondary antibody (red), and nuclei were stained with DAPI (blue). At least 10 midguts were examined for each treatment. Scale bar = 100 μm. Representative images are shown. d Immunoblot analysis of virus accumulation in whiteflies after feeding on TbCSV(Y35)-, TbCSV(Y41)-, or TbCSV(Y35-2C4)-infected WT and slpen3 knock-out tomato plants. Total protein of 150 whiteflies was extracted for immunoblot per treatment. Histone H3 was used as a loading control. e–g Immunoblot analysis of TbCSV(Y35) (e), TbCSV(Y41) (f), and TbCSV(Y35-2C4) (g) accumulation in WT tomato plants inoculated with 1, 5, 15, or 45 viruliferous Zhejiang II whiteflies acquiring virus from TbCSV(Y35)-, TbCSV(Y41)-, or TbCSV(Y35-2C4)-infected WT or slpen3 knock-out tomato plants. TbCSV was detected using a monoclonal antibody against the TbCSV coat protein (CP). Actin was used as a loading control. Tomato plants were given an inoculation access period of 48 h with 1, 5, 15, or 45 viruliferous whiteflies using clip cages in three independent biological replicates. Total protein was extracted from WT tomato plants at 14 days after the inoculation access period. Experiments in (b–d) were repeated at least three times with similar results.
