Meiotic analyses ofCucumis hybrids and an evolutionary evaluation of the genusCucumis (Cucurbitaceae)

Cucurbits (Cucurbitaceae; Cucumis spp., Cucurbita spp., Citrullus spp.)

“…Fruit set is stimulated in C. melo and C. sagittatus by members of Cucumis ser. Angurioidei, but not by C. humifructus or C. metuliferus (Raamsdonk, den Nijs, and Jongerius 1989). Promising results were obtained by den Nijs and Custers (1990) after crossing C. sativus var.…”

“…This variability has, in fact, been exploited to overcome hybridization barriers in wild African Cucumis species (Visser and den Nijs 1983). These examples and many others (see Raamsdonk, den Nijs, and Jongerius 1989) suggest that biosystematic and gene-pool studies can guide the selection of genotypes to increase the probability of successful interspecific hybridization.…”

“…In cucurbit crop species, genetic diversity analysis has been rigorously applied primarily to C. sativus and C. melo to determine the nature and structure of their gene pools and to examine hypotheses that may provide insights into the nature of their domestication (Bates and Robinson 1995). These gene pools are now relatively well described in relation to their evolution, migration, and differentiation (e.g., Raamsdonk, den Nijs, and Jongerius 1989;Horejsi and Staub 1999). The concept of gene pools is also rather well elaborated for Cucurbita spp.…”

“…Based on their geographic distributions, morphological characteristics, chromosome numbers, isozyme banding patterns, chloroplast DNA profiles, and patterns of interspecific hybridization, the species of genus Cucumis fall into two principal groups, generally recognized as subgenera (Jeffrey 1980;Raamsdonk, den Nijs, and Jongerius 1989;Kirkbride 1993). Sometimes these groups have been treated as distinct genera (as Cucumis and Melo) (Pangalo 1951), but that classification has not been commonly accepted.…”

“…The nature of these relationships is important for the application of appropriate technologies to transfer desirable genes from wild Cucumis species to cucumber and melon and between cucumber and melon (Bates and Robinson 1995). Many researchers have attempted to make interspecific crosses in Cucumis, and data resulting from initial efforts was summarized by Raamsdonk, den Nijs, and Jongerius (1989). Complex experiments on crossing ability within the genus have been conducted by den Nijs and Custers (1990) with the aim of transferring valuable characters from wild species from Africa cultivated C. sativus and C. melo.…”