SANDAL SPIKE MYCOPLASMAL DISEASE

1. MYCOPLASMAL DISEASE SANDAL
SPIKE
KARTHIK REDDY C A
2nd MSc Microbiology
Reg No – NP20AL62
NRUPATHUNGA UNIVERSITY BANGALORE
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2. Mycoplasma like organisms
• Mycoplasma is a prokaryotic microorganisms similar to
bacteria found by Nocard et al., in 1898, but does not
have a cell wall. In the past, it was called
pleuropneumonia like organism (PPLO). In 1967, It was
officially named as Mycoplasma.
• Mycoplasma-like organisms (MLOs) are wall-less
prokaryotes that cause disease in many higher plants
and in some causes in the insects that transmit them.
• However, recent sequence analysis of MLO 16S
ribosomal RNA has clearly established that these
pathogens from a unique cluster of organisms that are
phylogenetically related to gram positive bacteria and to
culturable mollicutes.
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3. Introduction
• Sandal ( Santam album L.) is an angiospermic semi-root parasite of
many plant species which grows to the size of a tree.
• It is a economically very important forest tree in India.
• In India the tree is common in the southern parts including states of
Karnataka, Tamil Nadu, and Kerala.
• Spike disease is effected to trees of all ages and size are attacked and
die within a few years of appearance of symptoms.
• This disease was first reported by Mc Carthy from Coorg district of
Karnataka state in 1899.
• It was earlier through to be caused by graft transmission and an insect
born virus.
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4. SANDAL SPIKE DISEASE
Pathogen : Mycoplasma Like Organism
Host : Sandal Wood Plants
Transmitted Through – Insect Vector – Moonia albimaculata
• Disease was first reported from Coorg district of Karnataka in 1903
• Disease was first though to be caused by viruses but in 1969 Varma et
al., reported that MLOs is the causal organism.
• Disease is confined to India and Indonesia.
• In India disease is common in Karnataka, Kerala, and Tamil Nādu.
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5. SYMPTOMS
This Yellows type of disease exerts witches broom effect.
Broadly the symptoms can be grouped into two categories
1. Rosette type
2. Pendulous spike type
Rosette type:
• It is characterized by severe reduction in leaves size and reduction of
internodes results in crowding of leaves on leaf bearing branches.
• The new leaves still more reduce in size such leaves become stiff and
stand like a spike.
• The leaves become reddish or yellowish.
• This symptoms appears just before death of trees.
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6. Cont…
• Flowers shows phyllody.
• Fruits are not formed.
• Root tip dies resulting in the loss of haustoria connection with host
plants.
• Ultimately the infected plants dry and die.
Pendulous Spike type:
• This is due to continuous apical growth of individual shoots with our
proper thickening and result in droping of shoots.
• Dormant buds remaining inactive and no resetting.
• Roots and haustoria not damaged.
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7. Source:
Arunkumar, A. N. & Joshi, Geeta. (2012). Incidence of sandal spike symptoms
in a one-year-old plantation in Karnataka. Current science. 103. 613-614.
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8. CAUSAL ORGANISM
• The spike disease of sandal was considered a virus disease. This
assumption was based on symptoms and graft sap transmissibility of
the causal agent.
• In 1969 electron microscope examinations confirmed that the disease
is caused by mycoplasma like organism (Phytoplasma).
• Which is found in the sieve tubes of leaves and twings showing
symptoms.
• Phytoplasmas are obligate bacterial parasites of plant phloem tissue
and of the insect vectors that are involved in their plant to plant
transmission.
• Phytoplasmas were discovered in 1967 by Japanese scientist who
termed them mycoplasma like organisms.
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9. PHYTOPLASMA
• The organism shows very high polymorphism.
• Phytoplasmas are unicellular prokaryotic phytopathogens and they
lack cell wall making them pleomorphic in nature.
• The size of cells of the pathogen in the host commonly occurring
forms bearing ellipsoidal which measure 180 – 200 × 250 – 300 nm.
• Some cells are elongated, measuring up to 750 × 150 nm. The smooth,
unit membrane bounding the cell is about 10 – 12 nm thick.
• The pathogen grows in the host best at 30 - 38°, below and above this
range the growth declines.
• They can not be grown on artificial media making it difficult to study
their biology.
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10. TRANSMISSION
• The disease can be transferred from Vinca rosea to sandal and vice
versa through dodder.
• The spike disease is spread through root contact and insect vectors.
• A large number of leafhoppers species seem to be involved in
transmission of the pathogen.
leafhoppers
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11. PHYSIOLOGY OF DISEASE PLANTS
• In diseased plants there is an accumulation of starch in branches and
leaves.
• Spiked plants contain lower amounts of calcium and have a higher
total ash content and nitrogen content in contrast to healthy plants.
• The ratio of calcium to nitrogen can be used as a diagnostic character
to see if the plants are infected or not.
• Nitrate reductase activity is higher in diseased plants that the healthy
ones.
• Spiked plants show lower iron content resulting in chorosis of the
leaves.
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12. Source:
Teixeira da Silva, Jaime & Kher, Mafatlal & Soner, Deepak & Nataraj, M.. (2016). Sandalwood spike disease: a
brief synthesis. Environmental and Experimental Biology. 14. 199-204. 10.22364/eeb.14.26.
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13. DISEASE MANAGEMENT
• So far no effective method of controlling the disease is known.
• If the past attempts have been made to cure the trees by raising the
temperature above 38° by building fires in trenches around affected trees.
• Different host plants of sandal impart resistance or susceptibility to the
disease in sandal. Among the host plants through which sandal acquires
resistance are Azadirachta indica, Cassia siamea, etc.
• Planting of Mysore gum plants (Eucalyptus tereticornis) at a distance of 10
– 20 meters from the sandal trees keeps the latter free of infection.
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14. CHEMICAL CONTROL
• Sandal spike shows remission of symptoms after treatment with
Tetracycline.
• Most tetracyclines including doxycycline and oxytetracycline were
effective when 500mg per tree was infused in 500ml of water.
• The systemic fungicide Benlate has been reported to bring about
temporary remission of symptoms.
• Application of the antibiotic by the girdling method has shown the
recovery of these 25 to 30 days after treatment with antibiotic
Terramycin either Benlate.
• 30 to 35 days after treatment with another antibiotic ledermycin alone
or in combination with Benlate.
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15. Reference
• Plant Pathology (Second Edition) by Ashok Aggarwal, R. S.
Mehrotra
• PLANT DISEASES | R. S. SINGH | Oxford (Ninth Edition)
• Fundamentals of Plant Pathology - Pathak M. Khatri N.K.
Pathak V.N.
• AGRICULTURAL MICROBIOLOGY - D. J. BAGYARAJ, G.
RANGASWAMI
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