Cucurbit Genetics Cooperative Report 3:80-81 (article 39) 1980
STOCKS AND GERMPLASM DESIRED OR FOR EXCHANGE
T. C. Wehner
Chlorophyll deficient stocks of Cucumis sativus,
including lines with any of the following genes: cd,
g, gc, ls, pl, v,
vvi, yc-1, yc-2, and yp.
Stocks for Exchange
G. W. Bohn, A. N. Kishaba, and J. D. McCreight
Cantaloupe breeding line WMR 29 is a high quality watermelon
mosaic virus (WMV) 1-resistant cantaloupe adapted to southwestern
desert production areas for use in cantaloupe breeding programs.
WMR 29 is also tolerant to high concentrations of minor
elements, sulfur dust, WMV race-3 and is heterozygous for
resistance to powdery mildew race-2.
WMR 29 was originated at the U.S Imperial Valley Conservation
Research Center at Brawley in cooperation with the Boyden
Entomology Laboratory at Riverside. The released seed is
the 17th inbred generation (Sib17=F) from the fifth backcross
(BC5) to breeding line PMR 29 (a sib of Campo) from the
cross PMR 29 x WMV 1-resistant line 90105. Line 90105 was
selected from PI 180280, a muskmelon used in soups and stews
in southern Asia (1).
Different selection and breeding procedures were used at
different locations in different series of generations to
combine the several resistances and tolerances with high
quality. Resistance to WMV race-1 derived from 90105 was
selected in greenhouse tests at La Jolla and Riverside.
Watermelon mosaic virus race-1 inoculated plants remain symptomless.
Tolerance to WMV race-2 was selected during spring with
natural infection in the Imperial Valley. Adaptation to desert
culture, freedom from crown blight, high fruit quality,
and plant longevity were selected in the field in the Imperial
Valley during both spring and summer.
Tolerance to high minor element concentration was tested
in the greenhouse ar Riverside by growing plants in a modified
Hewitt's solution with the minor elements five times more
concentrated than normal. Its source is unknown. Tolerance
to sulfur dust for powdery mildew control first observed
in a Blythe planting was confirmed in controlled field trails
at the University of California Imperial Valley Field Station.
Its source is unknown. Resistance to powdery mildew race-2
derived from PMR 29 is controlled by the single gene Pmr-2.
WMR 29 is segregating for resistance to powdery mildew race-2
since selection for homozygous resistant plants was not
WMR 29 produces well-netted, nearly spherical fruits with
well-defined tracks, thick salmon-colored flesh, dry seed
cavity and high soluble solids content. Fruits are extremely
hard at fully slip and, thus, should withstand mechanical
harvest and cross-country shipment.
WMR 29 retains considerable heterozygosity due to mass
selection of open pollinated fruits for ten generations.
It should be kept under selection pressure for fruit quality.
Muskmelon breeders desiring seed of WMR 29 should submit
written requests to Dr. James D. McCreight, U.S. Agricultural
Research Station, P.O. Box 5098, Salinas, CA 93915 or to
Dr. Albert N. Kishaba, U.S. Boyden Entomology Laboratory,
University of California, Riverside, CA 92521.
- Webb, R. E. 1979. Inheritance of resistance to watermelon
mosaic virus in Cucumis melo L. HortScience