Cucurbit Genetics Cooperative Report 7:64-65 (article
Independence of Genes Ses-B and M in Cucurbita pepo L.
Bloksberg, L.N. and O. Shifriss
Department of Horticulture and Forestry, Cook College, Rutgers-
The State University, New Brunswick, NJ 08903
Gene B conditions precocious depletion of chlorophyll in fruits leading
to precocious fruit yellowing. In addition, B can deplete chlorophyll
in leaves at early stages of plant development leading to leaf yellowing.
This effect is particularly severe at low temperatures (3). However, gene Ses-B selectively suppresses the expression of B in leaves (6).
Thus, plants of the B/B Ses-B/Ses-B genotype
produce precociously yellow fruits, but their leaves appear persistently green
as those of B+/B+ individuals.
Gene M conditions the mottled-leaf characteristic (2). The latter was
also described as the silvery-leaf trait (5). This is a complex trait and
some data suggest that it can impart a tendency to escape aphid-transmitted
viruses (1, 4, 7).
'Jersey Golden Acorn' (JGA) is B/B Ses-
B+/Ses-B+ m/m. It produces
precociously pigmented fruits, is susceptible to leaf yellowing, and bears
non-silvery leaves. We attempted to substitute Ses-B for Ses-
B+ and M for m in JGA by crossing it with one of
our breeding lines, NJ4, B/B Ses-B/Ses-B M/M, followed by several backcrosses to JGA. This operation
gave us an opportunity to study the relationship between Ses-B and M. The data in Table 1 clearly show that the two genes are independent.
The incorporation of both Ses-B and M into JGA may increase the
economic value of this cultivar.
Table 1. Independence of genes Ses-B and M.
Number of plantsa in respective classes
P1, 'Jersey Golden Acorn'
B/B Ses-B+/Ses-B+ m/m
B/B Ses-B/Ses-B M/M
F1, P1 x P2
BC1, F1 x P1
aAll plants were grown under controlled conditions: 16 hr
photoperiod, light 11 x 103 lu/m2, 95% from fluorescent tubes and
5% from incandescent bulbs, 20 C day and 15 C night.
bThe origin of this plant is not known, but it could reflect a
low penetrance of the silvery-leaf trait among m/m individuals of
- Davis, R.F. and O. Shifriss. 1983. Natural virus infection in
silvery and non-silvery lines of Cucurbita pepo L. Plant Disease
- Scarchuk, J. 1954. Fruit and leaf characters in summer squash.
J. Hered. 45:295-297.
- Shifriss, O. 1981. Origin, expression, and significance of gene B in Cucurbita pepo L. J. Amer. Soc. Hort. Sci. 106:220-231.
- Shifriss, O. 1981. Do Cucurbita plants with silvery leaves
escape virus infection? Origin and characteristics of NJ260.
Cucurbit Genetics Coop. Rpt. 4:42-43.
- Shifriss, O. 1982. On the silvery-leaf trait in Cucurbita pepo L. Cucurbit Genetics Coop. Rpt. 5:48-50.
- Shifriss, O. 1982. Identification of a selective suppressor
gene in Cucurbita pepo L. HortScience 17:637-638.
- Shifriss, O. 1983. Reflected light spectra from silvery and
non-silvery leaves of Cucurbita pepo L. Cucurbit Genetics Coop.