Studies on Molecular Variations in Puccinia arachidis Speg. Causing Rust of Groundnut
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Date
2011
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UAS, Dharwad
Abstract
An investigation was carried out to study morphological and molecular
variation in Puccinia arachidis Speg. Five isolates were collected from different
varieties grown in MARS, Dharwad and ten isolates from other locations.
Morphological variation was studied by considering uredospore morphology.
Molecular variation was studied by PAGE technique using selected isozymes and
RAPD technique using ten random primers.
In morphological variation, the dimension of uredospores of all isolates was
in the range of 21-26 × 18-21 μm. Nearly all spores had light cinnamon colour and
globose to ovoid shape. The pits on the surface of the spores were observed in
Annigere, Bellary, Jalgaon and Kolhapur isolates only. The echinulations were scarce
to fine in all isolates. A teleospore measuring 30.64 x 19.33 μm was found in the
Gadag isolate. This is a rare occurrence and needs further study.
PAGE analysis of Peroxidase revealed two distinct groups in Dharwad
isolates. Dh-86, Dh-101, GPBD-4 and JL-24 isolates formed one group
whereas and TAG-24 isolate formed another group. In other locations, Gadag isolate
formed a distinct group. Other isolates formed another group. Polyphenol oxidase
analysis too revealed two distinct groups in Dharwad isolates. Dh-86, Dh-101 and JL-
24 isolates formed one group whereas GPBD-4 and TAG-24 isolates formed another
group. In other locations too, Jalgaon isolate formed a distinct group. Other isolates
formed another group.
In case of molecular variation with the RAPD markers, OPD-18 (5’-
GAGAGCCAAC-3’) gave highest amplification. RAPD analysis revealed two
distinct groups within Dharwad isolates. Dh-86, Dh-101 and TAG-24 isolates formed
one group. GPBD-4 and JL-24 isolates formed another group. In other locations,
Dharwad and Raichur formed a distinct group. Rest of the isolates formed another
group.
Isozyme studies with PAGE and RAPD revealed minor variation in the
pathogen in spite of insignificant morphological variation; which is useful to
understand host-pathogen interaction.