Pathogenic Microbiology and Epidemiology MCB 402) Course co-ordinator: Odedara, O.O.
*1Department of Microbiology, University of Agriculture, Abeokuta, Nigeria (UNAAB)
Bacteria as plant pathogens • Bacteria are ubiquitous and physiologically diverse • Most bacteria plant pathogens possess common morphological characteristics such as slightly curved rods with rigid cell walls • Some have facultative anaerobic metabolism • Bacteria plant pathogen could be Gram positive or Gram negative • Acidovorax, Agrobacterium and Bulkholderia are examples are examples of Gram negative ones
Materials and Methods • The few Gram positive pathogens are mainly contained in the genera Curtobacterium and Streptomyces
Significant bacteria plant pathogens • Gram negative genera (Agrobacterium) -A member of the family Rhizobiaceae -found in the soil and plant roots -some are phytopathogenic -they invade the stem, crown and the root of dicotyledonous plants -Some species cause the transformations of plant cells into tumour cells e.g. Agrobacterium tumefaciens
Gram positive genera - Member of the family Streptomycetaceae • Produces vegetative hyphae • Widely distributed in soil • E.g Streptomyces ipomoeae which causes scab in sweet potato
Transmission of plant bacteria pathogens • Dissemination is by: • Water • Wind • Soil movement etc. Other plant pathogens include: • Fungi • Viruses
They can be transmitted through similar routes as in bacteria • Control of plant pathogens include: • Cultural methods • Sanitary measures • Biological controls • Roguing etc
Selected crop diseases of plants • Cassava mosaic disease (CMD) • Characterised by formation of irregular yellow patches • Known as mosaic • Caused by African cassava mosaic virus (ACMV) • Transmitted by whiteflies (Bemisia tabaci) • Known to cause about 0-82% crop loss • Had been reported throughout all cassava growing areas of Africa
Control of CMD • By: • Phytosanitation • Vector control • Use of resistant cultivar etc.