Fastidious vascular bacteria (FVB)
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Fastidious vascular bacteria (FVB), also known as Rickettsia-like bacteria or Rickettsia-like organisms, are small, non-motile bacteria that inhabit the vascular system of plants and reproduce by binary fission. They are transmitted by insect vectors and cause diseases in various crop plants such as citrus greening, Pierce's disease of grapevines, and clover club leaf. FVB that inhabit the xylem cause symptoms like leaf necrosis, stunting, and yield reduction, while those limited to the phloem cause stunting, yellowing, and premature death. Examples include Leifsonia xyli subsp. xyli in sugarcane and Xylella fastid
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Fastidious vascular bacteria (FVB)
- 1. FASTIDIOUS VASCULAR BACTERIA (FVB) N.H. SHANKAR REDDY 2ND PH.D. PLANT PATHOLOGY ANNAMALAI UNIVERSITY
- 2. Fastidious vascular bacteria are otherwise called Rickettsia like bacteria, Rickettsia like organisms (RLO), or fastidious prokaryotes or rickettsia -like walled bacteria. • They are non-motile bacteria measuring about 200 -300 nm in diameter, have cell wall, plasma membrane and cytoplasm containing ribosomes and DNA strands and are obligate • They reproduce by binary fission and mostly transmitted by insect vectors. • Contain enzyme for ATP production. • Penicillin and sulpha drugs are effective against RLB. • Eg. Club leaf of clover, citrus greening, pierce disease of gape wine.
- 3. Xylem-limited RLB • Symptoms: Symptoms include marginal necrosis of leaves, stunting of plants, decline in vigour and reduction in yield. Gram positive – Leifsonia xyli subsp. xyli (sugarcane ratton stunting) Gram negative – Xylella fastidiosa (Pierce’s disease of grapewine), transmitted by vector, glassy winged sharp shooter (Homolodisca vitripennis)
- 4. Phloem-limited RLB • Symptoms: Stunting, yellowing of young leaves, virescence of floral parts, premature death of the entire plant Gram negative – Candidatus liberibacter asiaticus (citrus greening or huanglongbing, transmitted by psyllids), Diaphorina citri (African greening).