The genetic basis of pear-shaped tomato fruit |
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Authors: | H-M Ku S Doganlar K-Y Chen S D Tanksley |
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Institution: | (1) Department of Plant Breeding and Biometry, 252 Emerson Hall, Cornell University, Ithaca, NY 14853-1902, USA, e-mail: sdt4@cornell.edu, Fax: +1-607-255-6683, US |
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Abstract: | Molecular-marker analysis of a cross between yellow pear, a tomato variety bearing small, pear-shaped fruit, and the round-fruited,
wild species, Lycopersicon pimpinellifolium LA1589, revealed that pear-shaped fruit is determined largely by a major QTL on chromosome 2 and, to a lesser extent, a minor
QTL on chromosome 10. The locus on chromosome 2 was also detected in a cross between yellow pear and the round-fruited introgression
line (IL2–5) which carried the distal portion of chromosome 2 from the Lycopersicon pennellii genome. Based on its map position, we propose that the locus detected on chromosome 2 is the same as a locus referred to
as ovate in the early tomato literature (Linstrom 1926, 1927). The fruit-shape index (length/diameter) and neck constriction were
highly correlated in both populations suggesting that ovate exerts control over both traits or that the genes for these traits are tightly linked on chromosome 2. Using two-way ANOVA
test, the minor QTL on chromosome 10 showed no significant interaction with the ovate locus on chromosome 2 with respect to the fruit-shape index. For ovate round fruit was dominant to elongated fruit in the L. pimpinellifolium populations, but additive in the IL2–5 population. Thus far, no genes controlling fruit shape have been cloned. The molecular
mapping of the ovate locus may ultimately lead to its isolation via map-based cloning.
Received: 8 January 1999 / Accepted: 30 January 1999 |
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Keywords: | Molecular markers Mapping Quntitative trait loci Fruit development Map-based cloning |
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