Cucurbit Genetics Cooperative Report 7:88 (article
A Nuclear Gene Codes for the Plastid-specific Aldolase in Cucurbita Species
Dept. Horticultural Sciences, New York State Agricultural
Experiment Station, Geneva, NY 14456
At least two forms of fructose 1,6-diphosphate aldolase (EC
184.108.40.206) are present in leaves of Cucurbita species. One
of these isozymes is localized in the plastid compartment while
the other is cytosolic (1). Polymorphism in the plastid-specific
aldolase has been observed using electrophoretic techniques. The
genetic basis of this polymorphism was investigated in the
backcross C. maxima x (C. maxima x C.
ecuadorensis) and in backcross and F2 populations
of a cross involving the two C. pepo cultivars 'Black
Jack' and 'Early Prolific Straightneck'. In all cases the
aldolase phenotype segregated as if controlled by a single locus
with codominant alleles (Table 1). The locus has been designated Aldo-p, the suffix reflecting the intracellular
compartmentation of aldolase.
As is typical for allelic variants of isozymes, 'wild type' and
'mutant' terminology is not appropriate. Both allozymes perform
the identical biochemical catalysis, and it would be very
difficult to demonstrate which allozyme was derived from which.
I have used the term "fast" and "slow" to discriminate between
the two allozymes segregating in each population. It should not
be assumed that the slow allozyme in the C. maxima x
(C. maxima x C. ecuadorensis) backcross is the same
as the slow allozyme in the C. pepo populations; instead,
4 Aldo-p alleles have probably been identified: 2 in C.
pepo, a third in C. maxima and a fourth in C.
Table 1. Number of individuals with designated aldolase
phenotypes in three segregating populations.
C. maxima x (C. maxima x C. ecuadorensis)
Black Jack x Early Prolific Straightneck (F2)
Black Jack x (Black Jack x EPSN)
- Anderson, L.E. and V.R. Advani. 1970. Chloroplast and
cytoplasmic enzymes. Plant Physiol. 45:585.