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  • Author or Editor: Harry S. Paris x
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Abstract

The inheritance of fruit flesh color in Cucurbita pepo L. (squash, pumpkin) was studied in filial and backcross generation progenies of the cross between ‘Vegetable Spaghetti’, which has pale flesh, and ‘Precocious Fordhook Zucchini’, which has orange flesh. Orange flesh was found to be conditioned by two complementary dominant genes, B and L-2.

Open Access
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The fruits of Cucurbita pepo cv. Table Queen are light green when young, turn dark green by intermediate age (15-18 days past anthesis) and remain dark green through maturity. Three major genes are known to affect developmental fruit color intensity in C. pepo: D, 1-1, and 1-2. Table Queen was crossed with cv. Vegetable Spaghetti and with tester stocks of known genotype in order to determine the genetic basis of its developmental fruit coloration. The results from filial, backcross. and testcross generations suggest that Table Queen carries gene D, which confers dark stem and fruit color from intermediate fruit age through maturity. Table Queen also carries L-2. which confers Light Type 2 (a pattern of grayish green hue) fruit color from intermediate age, but D is epistatic to L-2. The genotype of Table Queen is D/D 1-1/1-1 L-2/L-2. Clear-cut results were not obtained -- regarding the genetic basis of the retention of green color through maturity of Table Queen fruits.

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Most cultivars of acorn squash (Cucurbita pepo), such as `Table Queen', have fruit that are light green when young, become dark green by intermediate age, and remain dark green through maturity, carrying genotype D/D l-l/l-1 L-2/L-2. Many other forms of C. pepo that carry this genotype, the most familiar being the Halloween and pie pumpkins, turn orange at maturity. The genetic basis for green color retention of acorn squash was investigated by crossing `Table Queen' with `Vegetable Spaghetti', `Fordhook Zucchini', and accession 85k-9-107-2 (the parental, filial, backcross, and testcross generation progenies being grown out in the field and observed and scored for fruit color at maturity, between 40 and 44 days past anthesis). The results indicated that the three stocks crossed with `Table Queen' carry two recessive genes, designated mature orange-1 (mo-1) and mature orange-2 (mo-2), which act in concert to result in complete loss of green color before maturity in 1-1/1-1 plants. `Table Queen' is Mo-l/Mo-1 Mo-2∼o-2. Genes D and mo-2 are linked, ≈15 map units apart.

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Summer squash (Cucurbita pepo L.) is grown in many temperate and subtropical regions, ranking high in economic importance among vegetable crops worldwide. A native of North America, summer squash has been grown in Europe since the Renaissance. There are six extant horticultural groups of summer squash: cocozelle, crookneck, scallop, straightneck, vegetable marrow, and zucchini. Most of these groups have existed for hundreds of years. Their differing fruit shapes result in their differential adaptations to various methods of culinary preparation. Differences in flavor, while often subtle, are readily apparent in some instances. The groups differ in geographical distribution and economic importance. The zucchini group, a relatively recent development, has undergone intensive breeding in the United States and Europe and is probably by far the most widely grown and economically important of the summer squash.

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Pumpkin and squash (Cucurbita L. spp.) are important cucurbit crops and are grown in almost all arable regions of the world. The three economically important species, Cucurbita pepo L., Cucurbita moschata Duchesne, and Cucurbita maxima Duchesne are highly polymorphic in fruit characteristics, inspiring much research into their inheritance. A comprehensive list of genes for Cucurbita was last published more than a decade ago. This new gene list for pumpkin and squash includes descriptions of gene interactions and the genetic background of the parents that had been used for crossing to allow easy confirmation of previous work and provide a sound foundation for further investigation. This gene list includes 79 loci for phenotypic/morphological traits and 48 polymorphic allozyme loci. Linkage and mapping are discussed.

Free access

Abstract

Data from a cross between ‘Table King’, B +/B +, bearing green fruits, and ‘Precocious Small Sugar’, B/B, bearing yellow fruits, revealed the existence of 2 independent modifier genes, designated Ep-1 and Ep-2, each of which can extend the boundaries of precocious fruit pigmentation conditioned by gene B. The effect of these modifiers of B is cumulative, but the dosage of B plays an important role in controlling the extent of precocious pigmentation. Some commercial hybrids are B/+ and these tend to produce bicolor fruits, an undesirable feature in squash. The present findings suggest that B/+ hybrids can produce yellow fruits exclusively, provided they carry 2 or more Ep genes.

Open Access

Most summer squash, Cucurbita pepo L., produce one flower bud per leaf axil, whereas some genotypes can produce two or more. The former genotypes are referred to as single-flowering, whereas the latter are referred to as multiple-flowering. The objective was to determine the mode of inheritance of multiple flowering. The zucchini ‘True French’, which is single-flowering, was crossed with Accession 1777, a nearly isogenic line of this cultivar, which is multiple-flowering. Parental, filial, and back-cross plants were grown in pots in the greenhouse and each of their first 15 leaf axils was scored for the number of flower buds. Nearly all F1 plants, regardless of the direction of the cross, and plants resulting from back-crossing to ‘True French’ were single-flowering. Approximately one-fourth of the F2 plants, regardless of the direction of the cross, and half of the plants of the back-cross to 1777 produced two flowers at one or more leaf axils. These results indicate that the ability to produce more than one flower per axil is conferred by a single recessive gene, herewith designated multiple flowering, symbol mf.

Free access

Abstract

The effects of gene B in Cucurbita moschata Poir. were studied by comparing 2 near-isogenic lines, PI 165561 (B+B+ ) and Precocious PI 165561 (BB) at 2 locations in Israel. B significantly increased femaleness and number of fruits, but decreased fruit size and yield and numerically decreased seed yield at one or both locations. Fruits of B+B heterozygotes were distinctly bicolor. There was a deficiency in the number of bicolor-fruited plants in BC6 progeny, the deviation from the expected 1:1 ratio of green-fruited to bicolor-fruited being significant. Overall, the effects of B in C. moschata were no different from its effects in C. pepo L.

Open Access

Abstract

Gene B of Cucurbita pepo L. conditions precocious yellow-fruit pigmentation and is incompletely dominant to its allele, B + (3). This gene is found in representatives of several C. pepo cultivar groups, including ornamental gourd, zucchini, straightneck, pumpkin, and acorn. In addition to its primary effect, gene B can have a number of secondary effects, such as yellow spotting of leaves, decreased fruit size, reduced yields, bright orange flesh color, increased carotene content of the flesh, and improved flavor. The extent to which a particular secondary effect is manifested is dependent upon the genetic background.

Open Access

Abstract

Precocious Caserta is a summer squash (Cucurbita pepo L.) of the vegetable marrow type. Unlike other vegetable marrows, its fruit are yellow with yellow broken stripes, and the flesh is bright golden yellow. Plant characteristics resemble those of ‘Caserta’, but leaves may exhibit much yellow spotting.

Open Access