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| Red Rot Disease |
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| Sugarcane plants |
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| Glomus Mosseae |
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| Glomus fasciculatum |
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| Colletotrichum falcatum |
Efficacy of VAM ( Vesicular – Arbuscular Mycorrhizal ) on Red rot Disease in
Sugarcane.
( My dissertation work for the award of the degree M.Sc in
Microbiology.)
In this work , efficacy of VAM ( Vesicular – Arbuscular Mycorrhizal ) on the red rot disease in
sugarcane ( Saccharum officinarum L ) was studied. In the present study , the
sugarcane plants were taken as host plants. Glomus
mosseae and Glomus fasciculatum
were taken as mycorrhizal members . Colletotrichum falcatum , causative agent of
red rot disease , was taken as a pathogen. The mycorrhizal members were inoculated
individually and also in combination with the pathogen. Some of the plant
products like phenol , ortho
dihydric phenol , peroxidase , catalase
, phenol oxidase and ascorbic acid oxidase which are involved in the defense mechanism
were analyzed .
Red rot of sugarcane , a seed – piece transmissible fungal
disorder , caused by colletotrichum falcatum , is the most serious disease in India
(Agnihotri , 1990 ). The disease has
been responsible for phasing out of numerous commercial sugarcane genotype like
CO 213 , CO 299 , CO 312 , CO 313 etc. ( S.pandey and V.P. Agnihotri , 1996 ) .
In the present analysis , it was observed Glomus
fasciculatum induced more phenol
production when the sugarcane was infected by Collectotrichum falcatum. The
same Glomus fasciculatum was responsible for increased production of ortho –
dihydric phenol in sugarcane following the infection of collectotrichum
falcatum. It has been observed that certain common phenolic compounds ( toxic
to pathogens ) are produced and accumulate at faster rate after infection.
Accumulation of phenols and phytoalexins in VAM plants has been reported (
Krishna and Bagyaraj , 1984; Morandi et al 1984 ) which have been found in
tissues of variety of plants during pathogenesis (Vidhya sekaran 1988).
In the present analysis , increased level of ascorbic acid
oxidase activity was observed in Glomus mosseae treatment than the other
treatments. Both catalase and peroxidase activities were observed in higher
level in the Glomus fasciculatuom treated sugarcane platns. Similarly the
phenol oxidase activity was also very high in the treatment of Glomus
fasciculatum inoculated after the inoculation of colletotrichum falcatum.
The VAM fungi are well known to bring about physiological
changes in plants via increasing various enzymatic activities ( Gianinazz et al
1991 ).
The increased peroxidase activity by VAM fungi may be due to
VAM inoculation also resulted in increased activity of phenol oxidase enzyme.
This increased phenol oxidase activity might be responsible for increased
phenolic contents in the plants. Peroxidase and phenol oxidase are important
enzyme of the defence mechanism of plants against pathogens. Both these enzymes
are involves in the oxidation of phenolic components into quinines , which are
toxic to the pathogen ( Nishimathur , 1995 ).
The present investigation once again proved that in a way
VAM is involved in the resistance mechanism of plants. Both Glomus mosseae
and Glomus fasciculatum are involved in the enhancement of defence
mechanism against red rot disease. But Glomus fasciculatum induces somewhat
better response over Glomus mosseae.
Note: Pictures are taken from internet.
