A Comparison of Fine Structural Features of Xanthomonas campestris pv. malvacearum Grown in Vitro and in Cotton Plant Lines PDF

Keywords

cotton plants, ribosomes, bacteris

Abstract

Ultrastructure of Xanthomonas campestris pv. malvacearum Grown in susceptible (Ac 44) and resistant (Im 216) cotton plants was compared with that of the same bacteria grown to late stationary phase in nutrient broth culture. Bacterial cells grown in broth contained many ribosomes throughout the cytoplasm, and DNA strands occupied the central part of the cell. Polyribosomes and osmiophilic vacuoles were present only in actively growing bacteria. In susceptible cotton plants, X. campestris pv. malvacearum had similar structural features to broth-grown bacteria. During late stages of disease, capsular coating material developed on those bacteria embedded in a fibrillar material in host intercellular spaces. In resistant plants, bacterial cells developed similar cytoplasmic structure with no polyribosomes or osmiophilic vacuoles and resembled bacteria in late disease stages of susceptible plants. Bacteria fixed at late stationary phase in broth differed from those fixed from leaf material in late disease stages. Broth grown bacteria exhibited dissolution, coalescence of ribosomes and nuclear material, as well as vacuole development within intact cell membranes. In late diseased cotton leaves, bacterial calls showed cell membrane degeneration