Cucurbit Genetics Cooperative Report 10:100-102 (article 52) 1987
Precocious Fruit Pigmentation in BwB+ Plants
of Cucurbita pepo L.
O. Shifriss
21 Walter Ave., Highland Park, NJ 08904
T.H. Superak
Harris-Moran Seed Co., 3670 Buffalo Rd., Rochester, N.Y.
14624
A BwBw line of 'Table King', B+B+,
background was developed in 1979. Gene Bw is a weak allele
of B (1). The fruits of the BwBw line
are precociously pigmented and similar to the fruits of 'Jersey Golden Acorn'
except that their distal and proximal ends tend to be green. The fruits
of the heterozygote, BwB+, of 'Table King' background
are highly variable in color, ranging from completely green to different
grades of bicolor. Some of these fruits exhibit one or more precociously
pigmented golden spots. Sectioning fruits through 200 spots of different
size showed that each spot is made up of 2 contiguous golden areas, in the
"skin" (rind, exocarp) and in the "flesh" (mesocarp).
No golden spot or area in the "flesh" was unassociated with a
contiguous counterpart in the "skin". Furthermore, casual observations
suggested that the sizes of the contiguous areas of each spot are possitively
correlated (Shifriss, unpublished; see Figure 1). The present statistical
data confirm this suggestion.
Heterozygous BwB+ plants were grown together and 33 of their
fruits, each exhibiting at least 2 spots of different size, were selected
for measurement. The fruits were sectioned through the widest external ("skin")
diameter of these spots and 2 measurements were taken of each spot: the
length of the borderline between the contiguous golden areas and the depth
of the internal golden area (Figure 1). We assumed that these parameters
reflect the sizes of the two areas of each spot.
As Table 1 shows, the coefficient of correlation (r) of the 2 parameters
is highly significant statistically (P<0.001), indicating that the sizes
of the contiguous areas vary in the same direction.
The consistent contiguity of the external and internal golden areas of
the fruit and the statistically significant correlation between the measured
parameters lead us to the following conclusion: Precocious pigmentation
in "skin" and "flesh" has a common ontogenetic origin
with respect to site and time at which gene B is expressed.
Table 1. Precocious pigmentation in spotted fruits of BwB+
plants of 'Table King' background. Correlation coefficient (r) for the exterior
diameter of a spot and its interior depth. From field studies, Rochester,
NY, 1986.
z Two spots of each fruit were measured, one spot being larger (a) than
the other (b)
y Refers to the length of the borderline common to the contiguous golden
areas of each spot. See text and Figure 1.
x Refers to the depth of the internal golden area of each spot. See text
and Figure 1.
Literature Cited
- Shifriss, O. 1981. Origin, expression, and significance of gene B in Cucurbita pepo L. J. Amer. Soc. Hort. Sci. 106:220-232.
