Reproduction and cytogenetic characterization of interspecific hybrids derived from Cucumis hystrix Chakr. × Cucumis sativus L.

Abstract

Interspecific hybrids between Cucumis hystrix Chakr. (2n = 2 x = 24) and Cucumis sativus L. (2n = 2 x = 14) were produced by means of F(1) (2n = 19) embryo rescue and subsequent chromosome doubling. The hybridity was confirmed by genomic in situ hybridization (GISH) and chromosome analysis. The amphidiploid (2n = 38) was self-pollinated and backcrossed to cucumber resulting in lines with improved crossability to C. sativus. Examination of shape, stainability, and germination rate of pollen grains and yield as a function of mature fruit set per ten pollinated flowers indicated a tendency for increased fertility in BC(1)S(1) progeny when compared to F(1) and amphidiploid offspring. Cytogenetic characterization of F(1) and amphidiploid progeny was performed. Generally normal meioses produced viable pollen grains, and fertilization resulted in partial fertility restoration in amphidiploid progeny. Chromosome anomalies such as "frying-pan trivalent", chromosome lagging and spindle mis-orientation were also observed. In most of the PMCs of the F(1) diploid hybrid progeny, 19 univalents were observed at diakinesis and MI. In the amphidiploid, more than 90% of the configurations at MI consisted of the predicted 19 bivalents and less than 5% contained multivalents [trivalents (2.3%) + quadrivalents (0.3%)], suggesting the presence of preferential pairing, and a distinctive parental genome as well. The chiasmata observed between homoeologous chromosomes further demonstrated the introgression of the C. hystrix genome into that of C. sativus.

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

“…sativus (Chen et al 1997b). Cucumis hystrix appears to possess economically important traits such as root-knot nematode resistance (Chen and Lewis 2000;Chen et al 2001), gummy stem blight (D. bryoniae) resistance, downy mildew (P. cubensis) resistance, unique nutritional qualities, and tolerance to growth under low irradiance and temperature (Chen et al 2003b;Chen, Moriarty, and Jahn 2004b).…”

“…sativusX C. hystrix matings, indicating maternal and paternal inheritance for certain morphological and molecular (RAPD) characters (Chen et al 2004c). The resulting amphidiploid (HHCC, 2n = 4x = 38) was designated as a new synthetic nothospecies (C. Xhytivus Chen) and has been reproduced in subsequent experiments, ultimately resulting in an array of amphidiploids that have been self-pollinated to produce viable seeds (Chen and Kirkbride 2000;Chen et al 2003b). More recently, hybridization experiments have produced allotriploids (2n=3x=26; genome designated as HCC) from amphidoploidXdiploid (C. sativus var.…”

“…sativus (C), respectively) were completely heterologous, chromosome-doubling experiments were initiated to restore fertility (Chen and Staub 1997). This doubling of chromosome number in F 1 interspecific hybrid progeny was accomplished by monitoring in vitro cultures for somaclonal variation (Chen et al 1998(Chen et al , 2003bChen and Adelberg 2000). Putative tetraploid somaclonal variants were initially identified by their unique morphological characters (e.g., serrated leaf edge) and then by chromosome counts (Chen et al 2003a(Chen et al , 2003b).…”

Cytogenetic comparison among three cultivars of cucumber (Cucumis sativus L.) by using post-heated DAPI band, 45S and 5S rDNA sites

“…In cytogenetic field, cucumber's chromosomes were studied in order to demonstrate their genomic characters (Trivedi and Roy 1970, Ramachandran and Seshadri 1986, Chen et al 2003, Tagashira et al 2006. The most standard references demonstrated that Cucumis sativus had the chromosome number of 2n=14, which was different from that of the other species of Cucumis (Dane and Tsuchiya 1976;Dane et al 1980).The basic karyotype was analyzed by the conventional method (Trivedi and Roy 1970;Sing and Roy 1974;Dane and Tsuchiya 1976;Ramachandran and Seshadri 1986;Hoshi et al 1998) and differential staining method such as C-banding method (Ramachandran and Seshadri 1986;Chen et al 1998;Hoshi et al 1998;Koo et al 2002), chromomycin A 3 (CMA) method and 4',6-diamidino-2-phenylindole (DAPI) staining method Hoshi et al 1999;Hoshi et al 2008).…”

Genetic and Ecological Consequences of Transgene Flow to the Wild Flora

“…[47], Cucumis sp. [48]). However, for numerous plant groups such approaches are very laborious and/or have low or no success (e.g.…”