An in vitro method for examining infection of soybean roots by Macrophomina phaseolina

Abstract

A general limitation when studying the early events in the infection process of a soil borne plant pathogenis the detection of the hypha arrival at the root surface. We describe a new method to infect plants with soilborne pathogens that may be applicable to examination of the prepenetration and the penetration phasesof other soil borne fungi as well as the early responses of the host plant. Development of the in vitro methodallowed us to obtain roots of soybean plants infected with Macrophomina phaseolina to characterize theinfection process. Using two infection systems we provide evidence that M. phaseolina produces hyalinestructures which are undetected by staining methods based on fungal chitin dyes and were identifiedexclusively by stained lipid vesicles produced by the pathogen within host tissues