A genetic map of squash (Cucurbita sp.) with randomly amplified polymorphic DNA markers and morphological markers

Abstract

A molecular and morphological marker map would improve our knowledge of Cucurbita genetics, and would facilitate efforts to breed improved summer and winter squash cultivars. Random amplified polymorphic DNA (RAPD) markers were used to construct a partial map of the Cucurbita genome. The mapping population was the BC1 progeny of the Cucurbita pepo L. yellow straightneck inbred A0449 and the tropical Cucurbita moschata Duchesne ex Lam. landrace 'Nigerian Local'. A0449 was the recurrent parent. This cross was chosen because of the relatively greater economic importance of summer squash, traits of value to be introgressed from the C. moschata parent, and maximized genetic variation from the interspecific cross. The map contains 148 RAPD markers in 28 linkage groups. Loci controlling five morphological traits were placed on the map. The map covers 1,954 cM, which is estimated to be 75% of the Cucurbita genome. The qualitative traits placed on the map include the B gene for fruit which turn yellow before anthesis, the M gene for silver mottling of leaves, and a locus controlling the intensity of rind color on mature fruit. Quantitative trait loci (QTL) associated with fruit shape and the depth of the indentations between primary leaf veins were identified.