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Specificity of the Envelopment of Bacteria and Other Particles in Cotton Cotyledons. Ali H. Al-Mousawi, Former graduate student, Department of Botany, Oklahoma State University, Stillwater 74078; P. E. Richardson(2), Margaret Essenberg(3), and W. M. Johnson(4). (2)Professor, Department of Botany, Oklahoma State University, Stillwater 74078; (3)Associate professor, Department of Biochemistry, Oklahoma State University, Stillwater 74078; (4)Professor, joint appointment with the Langston University Cooperative Research Program, Langston University, Langston, OK 73050, and Department of Plant Pathology, Oklahoma State University, Stillwater 74078. Phytopathology 73:484-489. Accepted for publication 28 October 1982. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-484.

During the hypersensitive response of cotyledons of incompatible cotton line Im 216 following infiltration with a suspension of Xanthomonas campestris pv. malvacearum, bacterial cells were observed by transmission electron microscopy to be enveloped by fibrillar materials and often covered by more dense cuticlelike materials on the host cell wall surfaces. Cells of the same pathovar were never enveloped in compatible cotton line Ac 44, whereas all cells of incompatible pathovar X. campestris pv. campestris were enveloped. In Ac 44, envelopes formed (without an accompanying hypersensitive response) around cells of compatible X. campestris pv. malvacearum that had been killed by heat, rifamycin, or ultraviolet light. Polystyrene latex particles 0.5 μm in diameter were not enveloped in cotyledons of either cotton line. However, the Gram-positive bacterium Micrococcus lysodeikticus and corn starch grains were both enveloped in Ac 44. These observations suggest that bacteria and other hydrophilic particles are generally enveloped at the surface of cotton cell walls, but that during compatible interactions envelopment is actively prevented.

Additional keywords: bacterial blight of cotton, hypersensitive response.