Abstract:
The study was undertaken on the blackeye cowpea mosaic virus
(BICMV) c ausmg a severe mosaic disease on cowpea (Vigna unguiculat a
(L.) Walp). It aimed at locating the sources of heritable resistance and
biochemical basis of disease resistance required for formulating effective
management practices to check the spread of the disease as well as
immunodetection. Among the 66 varieties screened, four were resistant, 29
moderately resistant, 27 moderately susceptible and six susceptible. Six
cross combinations were tried and F I hybrid seeds were collected for
further evaluation. Biochemical changes indicated a lower carbohydrate
content In the resistant variety, compared to susceptible variety.
Chlorophyll content decreased in susceptible variety due to virus infection.
A lower level of phenol content was observed in resistant variety. Increase
in protein content was observed in both susceptible and resistant varieties
upon inoculation. The defence related enzymes peroxidase, polyphenol
oxidase and phenylalanine ammonialyase were enhanced with virus
inoculation in susceptible variety. SDS-PAGE analysis of proteins with
samples extracted from plants at 15 DAI showed the presence of two novel
virus induced proteins in diseased samples. Native polyacrylamide gel
electrophoresis performed for polyphenol oxidase Isozyme revealed
significant difference between the genotypes analysed. Five isoforms were
found for Sharika and Malika and four for Co-6 and Pallichal local. There
was no difference in amino acid pa.ttern in healthy and diseased plant
samples in TLC, except for an increased expression of proline in healthy
and tyrosine in diseased sample. Immunodetection could help identifying
the viruses infecting cowpea as BICMV and CABMV using specific
mono clonal antibodies.
