Cucurbit Genetics Cooperative Report 10:83 (article 43) 1987
Electrophoretic Classification of Cucurbita Cultivars
J. T. Puchalski
Botanical Garden of the Polish Academy of Sciences, Warsaw, Poland
R. W. Robinson
Horticultural Sciences Department, New York State Agricultural Experiment
Station, Geneva, NY
Cucurbita mixta was not recognized as a distinct species
until 1930. Previously, members of this species were considered to be C.
moschata. Although separated by partial sterility barriers, the two
species are very similar in morphology. The taxonomic key feature, of the
peduncle of C. mixta being corky and not flared at its attachment
to the fruit, is not always reliable for distinguishing the two species.
A more reliable method of classification is by electrophoresis, since
C. moschata and C. mixta have distinct patterns
for esterase, peroxidase, peptidase, acid phosphatase, and other isozymes.
By means of isozyme analysis, we determined that some cultivars previously
considered to be C. mixta are actually C. moschata.
The term cushaw, like that of pumpkin and squash, refers to fruit type
and usage rather than to a taxonomic entity. Isozyme analysis revealed that
each of these terms has been used for cultivars of more than one species
of Cucurbita. 'Green Striped Cushaw' has isozymes of C. mixta,
agreeing with the previous morphological classification by Cutler and Whitaker
(2). 'White Cushaw' also was previously classified as C. mixta
(2), but it had isozymes of C. moschata. 'Golden Cushaw' also
had isozyme banding patterns characteristic of C. moschata.
'Tennessee Sweet Potato' has been reported (2) to be C. mixta,
but the isozymes of the accession of this cultivar we tested were typical
of C. moschata.
The Seminole Pumpkin, which has been cultivated for centuries by Indians
in Florida (3), was identified by Bailey (1) and Erwin (3) as C.
moschata, despite its peduncle being more typical of C. mixta
than C. moschata (3). Its isozyme phenotype, although distinctive
fr6m other T. moschata cultivars tested, is in agreement with the
Seminole Pumpkin being C. moschata. The isozyme evidence does not
support the theory (4) that 'Seminole' is derived from a cross between C.
moschata and C. okeechobeensis. Fertile hybrids were
easily obtained of 'Seminole' x 'Butternut', confirming that 'Seminole'
is C. moschata.
- Bailey, L. H. 1929. Addenda in volume II, particularly in relation to
nomenclature. Gentes Herbarum 2(7):427-430.
- Cutler, H. C. and T. W. Whitaker. 1956. Cucurbita mixta,
its classification and relationships. Bull. Torrey Bot. Club 83:253-260.
- Erwin, A. T. and E. P. Lana. 1956. The Seminole Pumpkin. Econ.
Bot. 10:33- 57.
- Morton, J. F. 1975. The sturdy Seminole Pumpkin provides much food
for thought. Florida State Hort. Soc. Proc. 88:137-142.