Cucurbit Genetics Cooperative Report 7:64-65 (article 28) 1984
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 | Total | Chi square | P | ||||
---|---|---|---|---|---|---|---|
Ses-B | Ses-B+ | ||||||
M | m | M | m | ||||
P1, ‘Jersey Golden Acorn’ B/B Ses-B+/Ses-B+ m/m |
0 | 0 | 1(?)b | 29 | 30 | — | — |
P2, NJ4 B/B Ses-B/Ses-B M/M |
30 | 0 | 0 | 0 | 30 | — | — |
F1, P1 x P2 | 20 | 0 | 0 | 0 | 20 | — | — |
BC1, F1 x P1 | 79 | 76 | 76 | 79 | 310 | 0.12 | >0.98 |
F2 | 89 | 28 | 28 | 12 | 157 | 0.63 | >0.85 |
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 some background. |
Literature Cited
- Davis, R.F. and O. Shifriss. 1983. Natural virus infection in silvery and non-silvery lines of Cucurbita pepo L. Plant Disease 67:379-380.
- 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. Rpt. 6:89-90.