Cucurbit Genetics Cooperative Report 5:39 (article 19) 1982
Helen Atthowe and O. Shifriss
Department of Horticulture and Forestry, Cook College, Rutgers – the State University, New Brunswick, NJ 08903
In the fall of 1981, during a routine work of transplanting squash seedlings, one of us (H.A.) discovered that the lower side of the cotyledons of some plants is white instead of green. This observation prompted us to obtain data on the incidence of white cotyledons in inbred varieties and progenies that were available at that time.
We report these data here (Tables 1 and 2) without comments because we are still ambivalent about their meaning. If white cotyledon is a heritable trait, as we presently believe, it would be interesting to determine its genetic basis as well as its adaptive value. It may also be a useful seedling marker.
The white color is usually confined to the central region of the lower side of the cotyledon. Preliminary examination suggests that the white color results from structural changes in the spongy parenchyma which affects the reflected light. But this possibility must be explored more critically.
Table 1. Incidence of plants with white cotyledons in inbred lines.
Inbred of |
Green |
White |
Total |
% white |
| ‘Caserta’ | 3 | 90 | 93 | 96.8 |
| Early Prolific Straightneck’ | 81 | 23 | 104 | 22.1 |
| ‘NJ260’ | 61 | 2 | 63 | 3.2 |
| ‘Fordhook Zucchini’ | 56 | 1 | 57 | 1.8 |
| ‘Jersey Golden Acorn’ | 80 | 0 | 80 | 0 |
Table 2. Incidence of plants with white cotyledons in some breeding progenies.
Parents z |
Offspring |
|||
Self-pollinated |
Green cotyledons |
White cotyledons |
Total |
% White |
| 1550-1 | 18 | 101 | 119 | 84.9 |
| 1550-2 | 103 | 67 | 170 | 39.4 |
| 1550-3 | 73 | 65 | 138 | 47.1 |
| 1550-5 | 165 | 2 | 167 | 1.2 |
| 1550-6 | 170 | 0 | 170 | 0 |
z These parents were the offspring of B2 generation obtained from the following operation: (1) Caserta x NJ260. (2) An F2 plant was backcrossed to Caserta B1. (3) An individual plant of B1 was backcrossed again to Caserta B2.