AN ABSTRACT OF THE THESIS OF
Muhammad Bashir for the degree of Doctor of Philosophy in
Plant Pathologypresented onSeptember 17, 1992
Title: Serological and Biological Characterization of
Seed-borne Isolates of Blackeye Cowpea Mosaic and
Cowpea Aphid-borne Mosaic Potyviruses in Vigna
unguiculata (L.)
Abstract approved: Redacted for Privacy Richar0. Hamp
Five viruses were detected in cowpea plant samples
from Pakistan:blackeye cowpea mosaic(B1CMV), cowpea aphid-borne mosaic (CABMV), cowpea mottle virus (CPMoV),
cowpea severe mosaic virus (CSMV), and southern bean mosaic
virus (SBMV). Neither cucumber mosaic virus (CMV)nor
cowpea mosaic virus (CPMV) were detected in these samples. Only CABMV was found to be seed-transmitted in four of
seven seed lots at rates of 0 to 7 percent. Although all
viruses occurring in cowpea in Pakistan were not identified, the present study has probably determined the
principal seed-borne viruses of cowpea.
Fourteen of 158 U.S. Vigna unguiculata Plant Introduction accessions tested for seed-borne potyviruses were found to be infected with B1CMV (6.9%)and CABMV (13.3%) potyviruses, and seven with CMV (2.0%) cucumovirus. Forty-three isolates of B1CMV and 55 of CABMV were derived from Vigna unguiculata accessions, pre- introductions and commercial cowpea plantings. Viral identities were determined by DAS-ELISA serology and verified by electron microscopy and host reactions.
The highest seed-transmission rates of 48.5% and 55% were produced by B1CMV isolate PI-2581 and CABMV isolate RN-27C respectively. Aphid transmissibility of these viruses byAphis craccivora Koch, using three aphids per inoculated plant,ranged from 24% to 55% among B1CMV isolates and 18% to 57% among isolates of CABMV.
Antiserum produced against a typical CABMV isolate
RN-7C, yielded CABMV-specific immunoglobulin G, when used in DAS-ELISA.
Twenty-one seed-borne isolates each of B1CMV and CABMV were compared for pathogenicity on 51 cowpea genotypes, and found to vary markedly in both pathogenicity and virulence. Based on differential reactions of these genotypes, 21 distinct variants of B1CMV and 25 of CABMV were identified. Two genotypes, TVU 401 and TVU 1582, were immune to all isolates of CABMV. Two other genotypes, TVU 2657 and TVU 3433, were immune to all isolates of B1CMV except those naturally seed-transmitted in the cowpea cultivar 'Pusa Phalguni' (India). Serological and Biological Characterization ofSeed-borne
Isolates of Blackeye Cowpea Mosaic and CowpeaAphid-borne
Mosaic Potyviruses in Vigna unguiculata (L.)Walp.
by
Muhammad Bashir
A THESIS
Submitted to
Oregon State University
in partial fulfillment of the requirement for the degree of Doctor of Philosophy
Completed September 17, 1992 Commencement June, 1993 APPROVED:
Redacted for Privacy Professor of Botany and Plant Phology in charge of major
Redacted for Privacy Head of Department of Botany and PlantPat ology
Redacted for Privacy Dean of Graduat chool
Date thesis is presented September 17, 1992 Typed by M. Bashir for Muhammad Bashir ACKNOWLEDGEMENTS
In the name of Allah, the most beneficent, the most
merciful:
It is my great privilege to thank Dr. R.O. Hampton, my major professor,for hisinvaluable technical advice,
assistance, patience and friendship in planning my thesis
research, andfor providing excellentlaboratory and
greenhouse facilities.
I am also grateful to the faculty members Dr. J. R.
Baggett, Dr. W. G. Dougherty, Dr. G. W. Krantz, and
Dr. C. C. Mundt, who served on my committee, and for their
valuablesuggestions