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Abstract: Gherkin (Cucumis anguria L.), also known as West Indian gherkin, burr gherkin, and maxixe, is mainly cultivated and consumed in Brazil and the United States. Marker-assisted selection (MAS) would be a highly desirable tool for breeding of gherkin as gherkin cultivation generally requires considerable time, labor, and space. However, DNA markers available for gherkin have rarely been reported, although many microsatellite linkage maps have been constructed for cucumber and whole genomic sequences have been reported. In this study, we attempted to transfer 86 microsatellite markers derived from cucumber to gherkin and assess amplification and polymorphism between two gherkin accessions to enable the use of the microsatellite markers in gherkin. In PI 320052 and PI 364475, 58 (67.4%) and 55 (64.0%) microsatellite markers were successfully amplified, respectively. Of the amplified markers, the polymorphism number between the two accessions was 40. Thus, an adequate number of cucumber microsatellite markers can be transferred to gherkin. Current polymorphic microsatellite markers could then be made available for the study of landmarks in linkages, genomic structures, evolutionary ecology, and MAS in gherkin and Cucurbitaceae. [Copyright &y& Elsevier]

Abstract: Wild Cucumis spp., which have resistance to various diseases, have the potential to be used for melon (C. melo L.) breeding. Nevertheless, few interspecific hybrids between melon and wild Cucumis spp. have been obtained because of strong reproductive barriers such as pollen–pistil incongruity and hybrid seed abortion. For this study, we examined the temperature conditions enhancing pollen tube growth and fruit set in interspecific crosses between melon and wild Cucumis spp. Before temperature-conditioned pollination, four wild Cucumis spp. were pollinated with the melon line ‘MR-1’ and two lines of C. anguria, PI 147065 and PI 320052, and a line of C. metuliferus, PI 526242, were selected for later experiments. These three lines were crossed reciprocally with ‘MR-1’ under controlled temperatures of 24–34°C at 2°C intervals. When ‘MR-1’ pistils were pollinated with three lines of wild Cucumis spp., pollen tube growth was arrested after germination at all temperatures. However, in the pistil of wild Cucumis spp., pollen tube growth of ‘MR-1’ was significantly greater at 32°C and at 34°C than that under 30°C. Furthermore, pollen tube length in pistils of PI 320052 and PI 526242 at 32°C was comparable to that of ‘MR-1’ self-pollination at 28°C. Fruit set frequency was also improved at 32°C. These results demonstrated that the pollen tube inhibition of Cucumis spp. interspecific crosses might be partially or fully recoverable in higher-temperature conditions. Moreover, 32°C is apparently the threshold temperature for promoting pollen tube growth in these cross combinations. [Copyright &y& Elsevier]