Cucurbit Genetics Cooperative Report 4:41-42 (article 22) 1981
Virus Studies with Cucurbita foetidissima
M. E. Rosemeyer and W. P. Bemis
University of Arizona,
Tucson, AZ 85721
Two isometric viruses have been isolated from field-grown
buffalo gourd (bg), Cucurbita foetidissima. Host
range studies, electron microscopy, and serology have been
used to identify these viruses as squash mosaic virus (SqMV)
and a cucumber mosaic-like (CMV-like) virus. These viruses
have then been reinoculated to buffalo gourd as well as
reisolated and characterized.
Host Range. After SqMV was transferred from buffalo
gourd to Cucurbita pepo var. 'sugar Pumpkin', the
viruses range was determined by inoculating cultivated species.
Squash mosaic virus-buffalo gourd did not infect Chenopodium
amaranticolor or Nicotiana tabacum var. 'Xanthi',
which is identical to known SqMV but unlike other isometric
The CMV-like virus has host range identical to known CMV
(ATCC PV-242, PV-59): local lesions (no systemic reaction
on C. amaranticolor, systemic mosaic on N.
tabacum var. 'Xanthi', local lesions (no systemic necrosis)
on cowpea, Vigna sinensis, thereby eliminating
tobacco ringspot virus (TRSV), tomato ringspot virus (TmRSV),
and SqMV. Its isometric shape eliminates the possibility
of watermelon mosaic virus (WMV).
Electron-Microscopy and Serology (Transmission
Electron Microscopic Serology). The SqMV-bg aggregates when
combined with SqMV antisera and viewed in the electron microscope.
These findings correspond to that of Ochterlony agar gel
The CMV-like virus disintegrated when stained with phosphotungstic
acid but is stable in uranyl acetate, as does known CMV.
The Derrick technique (1) has been employed to avoid the
aggregations present in the control when the previous technique
was used. Three different strains of ATCC CMV antisera (PVAS
30, 242, 260) have provided no conclusive results, though
two known strains of CMV (ATCC PV-59, PV-242) react moderately
to very well with the antisera. Tomato ringspot virus, TRSV,
alfalfa mosaic virus (AMV) and SqMV antisera were also tried
unsuccessfully, Agar gel tests have proved inconsistent.
Therefore, there are several possible identities of the
CMV-like virus: it is a known strain of CMV, which we do
not have antiserum to as yet, it is a unique strain of CMV,
it is not CMV but another virus, known or unknown.
Reinoculation to Buffalo Gourd and Subsequent Reisolation. When SqMV-bg was reinoculated to seedlings of buffalo gourd
in the greenhouse, a mild systemic mosaic appeared. However,
about 1-2 weeks later, the new leaves appear normal. Squash
mosaic virus was recovered from these buffalo gourd plant.
Known SMV II (Cantaloupe; Mesa, AZ) produced identical symptoms.
Similar symptom patterns appeared when the CMV-like virus
was reinoculated to buffalo gourd except that the mosaic
was very severe, leaves recurved. However, new leaves appeared
normal in three weeks. The virus was recovered from the
inoculated buffalo gourd. However, buffalo gourd is resistant
to known CMV (ATCC PV-59, PV-242). Provvidenti also reported
buffalo gourd as resistant to CMV in New York (2).
Watermelon mosaic virus (cantaloupe; Yuma, AZ) and TRSV
(ATCC PV-157) have been inoculated to seedling buffalo gourds
in the greenhouse. The plants were mechanically inoculated
three times over a 10-day period, allowed to express symptoms
for one month, viewed in the electron microscope, and then
inoculated to appropriate host plants. Buffalo gourd has
proved resistant to both WMV and to RSV, which has concurred
with observations of Provvidenti (2).
- Derrick, K. S. and R. H. Brlansky. 1976. Phytopathology 66:815-820.
- Provvidenti, R., R. W. Robinson and H. M. Munger. 1978.
Research in feral species to six viruses infecting Cucurbita.
Plant Disease Reporter 62:326-329.