Analysis of cell-to-cell and long-distance movement of a bean dwarf mosaicgeminivirus-green fluorescent protein reporter in host and nonhost species: Identification of sites of resistance

A bean dwarf mosaic geminivirus-green fluorescent protein (BDMV-GFP) report er system was employed to analyze the viral infection process in host and n onhost species. Five classes of BDMV/host interaction were identified: (i) adapted hosts (susceptible Phaseolus vulgaris cultivars) permissive for sys temic infection; (ii) adapted hosts (resistant P. vulgaris cv, Othello) dis playing the development of a hypersensitive response (HR) associated with r esistance to systemic infection; (iii) adapted (resistant P: vulgaris cv, B lack Turtle Soup T-39) and nonadapted (Vigna unguiculata) hosts in which ce ll-to-cell, but not long-distance, movement was permitted; (iv) nonadapted hosts (Glycine mar) in which systemic infection was coat protein-dependent; and (v) nonhosts (Cucurbita maxima, Gossypium barbadense, and Zea mays) in which the virus was confined to inoculated cells, Confocal laser scanning microscopy, fluorescence microscopy, and histochemical analyses were used t o identify the cellular distribution of BDMV-GFP and the host response to v iral infection, With this approach, the HR in P. vulgaris cv, Othello was v isualized within cells of the epidermis, cortex, and phloem of inoculated h ypocotyls, Infection studies performed with four begomoviruses and infectio us BDMV/tomato mottle geminivirus pseudorecombinants revealed that the HR d eterminant(s) mapped to the BDMV DNA-B component.