Revisiting the Source of Wilt Symptoms: X-Ray Microcomputed Tomography Provides Direct Evidence That<i>Ralstonia</i>Biomass Clogs Xylem Vessels

Ralstonia causes wilt diseases by colonizing xylem vessels and disrupting water transport. The dogma is that bacterial biomass clogs reduces the flow of sap due to abundance. However, physiological mechanism disruption during untested. Using a tomato pseudosolanacearum GMI1000 model, we visualized quantified spatiotemporal dynamics wilt. First, measured stomatal conductance leaflets on mock-inoculated wilt-symptomatic plants. Wilted had reduced conductance, as did turgid same petiole wilted leaflets. Next, used X-ray microcomputed tomography (X-ray microCT) light microscopy differentiate between mechanisms disruption: blockage biomass, vascular tyloses, or displacement gas embolisms. We imaged intact plant stems quantify embolized vessels. Embolized were rare, but infected plants with low populations nonsignificant trend more vessel To test whether are clogged wilt, excised after brief dehydration. Most in mock-infected emptied their contents excision, nonconductive abundant 2 days post infection. At onset, when exceeded 5 × 10 8 CFU/g stem tissue, approximately half electron-dense biomass. found no evidence tyloses microCT reconstructions from preserved stems. Therefore, appears be principal cause [Formula: see text] author(s) have dedicated work public domain under Creative Commons CC0 “No Rights Reserved” license waiving all his her rights worldwide copyright law, including related neighboring rights, extent allowed 2022.