Bacterial Plant Pathogens What are bacteria?What are bacteria? Bacterial identificationBacterial identification Generalized disease cycleGeneralized disease cycle Disease symptomsDisease symptoms Disease controlDisease control

Bacterial Plant Pathogens Size ( x um ) Generally single celled Reproduce by simple fission

Prokaryotes No membrane bound nucleus or organelles Lack chlorophyll Most have cell wall Some are motile – flagellum (a) Single circular chromosome

Structure cell shape colony appearance motility (flagella) Identification

Biochemical cell wall composition

Identification Respiration aerobic, anaerobic, facultative anaerobic Nutritional requirement (C, N, {Biolog}) Fatty acids {FAME} Serology Nucleic acids

Identification Pathogenicity

Plant Pathogenic Bacteria (for PLPA3004) 8 genera of bacteria, 1 of uncertain ID8 genera of bacteria, 1 of uncertain ID 2 genera of Mollicutes (lack cell walls2 genera of Mollicutes (lack cell walls Approximately spp. (200 pathovars {pv.})Approximately spp. (200 pathovars {pv.}) Pathovar – pathogenic on a specific host (crop)Pathovar – pathogenic on a specific host (crop)

Plant Pathogenic Bacteria (for PLPA3004) Most are facultative parasites,Most are facultative parasites, –Except fastidious bacteria and mollicutes Most are gram-, rod-shaped bacteriaMost are gram-, rod-shaped bacteria

Fastidious vascular bacteria Vectored by leafhoppers, except ClavibacterVectored by leafhoppers, except Clavibacter Unknown-phloem limited bacterium not culturableUnknown-phloem limited bacterium not culturable Symptoms – stunting, leaf scalding, declineSymptoms – stunting, leaf scalding, decline Xylella – Pierce’s disease of grapeXylella – Pierce’s disease of grape

Mollicutes Lack cell wallLack cell wall Phloem limitedPhloem limited Transmitted by leafhoppersTransmitted by leafhoppers Phytoplasmas – amorphousPhytoplasmas – amorphous Spiroplasmas - helicalSpiroplasmas - helical Symptoms – yellows diseases, witches’ brooming, stuntingSymptoms – yellows diseases, witches’ brooming, stunting Sensitive to TetracyclineSensitive to Tetracycline

Disease cycle Overseasoning 2 cycle Dissemination Penetration Disease development Reproduction o

Disease cycle Protected environment

Disease cycle short distance 1.Water 2. Soil 3. Tools and equipment 4. Insects

Disease cycle

Disease control

Disease Control

Symptoms