Cucurbit Genetics Cooperative Report 4:32-33 (article 16) 1981
Hypersensitivity to Anthracnose Infection in Citrullus
B. B. Rhodes
Edisto Experiment Station, P. O. Box 247,
Blackville, SC 29817
Van der Plank (3) discussed the hypersensitivity reaction
in plants as first defined by Muller. It includes the morphological
and histological change that when produced by an infectious
agent, elicit the premature dying of the infected tissue
as well as the inactivation and localization of the infectious
Two very different types of hypersensitive reactions to
Colletotrichum lagenarium, isolate CIBR (2), have
been noted in Citrullus lanatus. The most common
type is rapid wilting and death of the infected leaf. The
other type is not as common and does not elicit rapid wilting
and death of the leaf. Instead, yellowing occurs around
the lesion and may extend over the entire leaf. In some
plants the pale area of the leaf is well defined; in others,
the entire plant may be notably paler than normal.
In a line derived from PI 189225, initial lesions on plants
showing leaf yellowing were smaller than lesions on plants
hypersensitive to the pathogen. Plants in this line segregated
into 38 non-hypersensitive, 16 hypersensitive. Another line
derived from a single plant of PI 299778, which did not
demonstrate the yellowing response to inoculation, did not
exhibit the traits among eight progeny. F2 progeny from
a cross of 'Dixielee' with a plant of PI 299778, which did
exhibit the trait, segregated 31: 5 for non-hypersensitivity:
Extracts from four young lesion-free leaves were taken
from a single hypersensitive plant and a single non-hypersensitive
plant of the PI 189225 progeny. Slab gel electrophoresis
with SDS (1) revealed an additional protein in the extract
from the hypersensitive plant.
- Conejero, V. and J. S. Semancik. 1977. Analysis of the
proteins in crude plant extracts by polyacrylamide slab
gel electrophoresis. Phytopathology 67: 1424-1426.
- Sowell, Jr., G., B. B. Rhodes and J. D. Norton. 1980.
New sources of resistance to watermelon anthracnose. J.
Amer. Soc. Hort. Sci.105: 197-199.
- Van der Plank, J. E. 1968. Disease Resistance in
Plants. Academic Press, New York. p. 124.