Dark-stem-dependent reverse fruit striping in Cucurbita pepo (pumpkin, squash, gourd: Cucurbitaceae): Genes l - 2 and W
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Dark-stem-dependent reverse fruit striping in Cucurbita pepo (pumpkin, squash, gourd: Cucurbitaceae): Genes l-2 and W are at the same locus Harry S. Paris
Received: 6 July 2020 / Accepted: 26 September 2020 Ó Springer Nature B.V. 2020
Abstract Cucurbita pepo contains a wealth of genetic variability in fruit size, shape, and color. A common fruit color pattern in C. pepo is striping of the fruits. Stripes occur on the fruit exterior in accordance with the positions of the 10 main subepidermal vein tracts, and can be normal, with darker stripes occurring between and lighter stripes over and adjacent to the vein tracts, or reversed, with lighter stripes occurring between and darker stripes over and adjacent to the vein tracts. Reverse striping has been reported as being independent and at other times dependent on the presence of the dominant allele for dark stem color, D. The objective of this investigation was to determine the relationship, if any, between the two types of reverse striping, dark-stem-dependent and independent. For this purpose, two accessions, which when crossed produced progeny having dark-stem-dependent reverse striping, were crossed with seven nearisogenic tester accessions of known genotype. The results indicated that the two types of reverse striping are conferred by different alleles at the same locus,
which is also the same locus at which other alleles confer normal striping. The results of crossing among the nine accessions suggest that two genes reported as having major effects on fruit color, l-2 and W, are actually the same locus (or two tightly linked loci). To minimize possible confusion, it is suggested that this multiple-allelic locus be hereafter referred to as l-2. This locus has seven alleles, of which the two top dominants, L-2WS and L-2W, and the bottom recessive, l-2, confer the exact same fruit phenotype, weak coloration. Two intermediate alleles, L-2 and L-2i, result in intense fruit coloration and normal striping, and two other intermediate alleles, L-2Wr and l-2R, respectively, confer dark-stem-dependent and independent reverse striping. The order of dominance of the seven alleles is L-2WS [ L-2W [ L-2Wr [ L2 [ L-2i [ l-2R [ l-2.
H. S. Paris (&) Department of Vegetable Crops and Plant Genetics, Agricultural Research Organization, Newe Ya‘ar Research Center, P. O. Box 1021, Ramat Yishay 3009500, Israel e-mail: [email protected]
Introduction
Present Address: H. S. Paris P. O. Box 6114, Yoqne‘am 2065626, Israel
Keywords Cucurbits Fruit coloration Fruit striping Multiple allelism
Striping of the fruit surface is a common feature among the Cucurbitaceae. This external striping is positioned in accordance with the placement of the main sub-epidermal vasculature of the ovaries and fruits. The ovaries of cucurbits are inferior to the calyx
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and corolla, and the vascular tracts (veins) connect the pedicel with the five sepals and five petals via the ovary (Duchesne 1786). Fruit striping is often
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