Detailed description about Fastidious vascular bacteria (FVB) and different examples are given

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).