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Wild Cucumis species have been divided into Australian/Asian and African groups using morphological and phylogenetic characteristics, and new species have been described recently. No molecular cytogenetic information is available for most of these species. The crossability between 5 southern African Cucumis species (C. africanus, C. anguria, C. myriocarpus, C. zeyheri, and C. heptadactylus) has been reported; however, the evolutionary relationship among them is still unclear. Here, a molecular cytogenetic analysis using FISH with 5S and 45S ribosomal DNA (rDNA) was used to investigate these Cucumis species based on sets of rDNA-bearing chromosomes (rch) types I, II and III. The molecular cytogenetic and phylogenetic results suggested that at least 2 steps of chromosomal rearrangements may have occurred during the evolution of tetraploid C. heptadactylus. In step 1, an additional 45S rDNA site was observed in the chromosome (type III). In particular, C. myriocarpus had a variety of rch sets. Our results suggest that chromosomal rearrangements may have occurred in the 45S rDNA sites. We propose that polyploid evolution occurred in step 2. This study provides insights into the chromosomal characteristics of African Cucumis species and contributes to the understanding of chromosomal evolution in this genus.

A molecular cytogenetic survey of Cucumis sativus L. revealed a chromosomal polymorphism among 2 European pickling cultivars of ‘Borszczagowski’ and ‘Monastyrski’, and one Japanese cultivar of ‘Zibai’ by fluorescent banding method with chromomycin A3 (CMA) and 4′,6-diamidino-2-phenylindole (DAPI), and fluorescence in situ hybridization (FISH) with the probes of 5S, 45S rDNA and telomere repeat sequences. Heterochromatic banding polymorphism was found in some chromosomes with CMA and DAPI staining, whereas no chromosomal polymorphism was found in FISH. Thus, the FISH allowed us to identify all of homologous chromosomes in each cucumber cultivars, while CMA and DAPI banding showed an easy detection of the polymorphism in cucumber chromosomes, even in close related cultivars between European pickling cultivars.

The positions of heterochromatic bands, 45S and 5S rDNA regions were detected on the chromosomes in three cultivars of cucumber (Cucumis sativus L.). The post-heated DAPI bands, which revealed heterochromatic region, were observed on the both terminal and pericentromeric regions of most of the chromosomes in three cultivars. However, these band patterns were different between European and Eastern Asian cultivars. The major 45S rDNA sites were found around the centoromeric region of the chromosomes 1, 2 and 5, and the minor 45S rDNA sites were found around centoromeric region of the chromosomes 3 and 7. The positional variation of this region was not found among three cultivars, but size difference was observed in the chromosome 5. The 5S rDNA site was observed on the interstitial region of the chromosome 6 in all of the cultivars studied. These results indicated that the variation of chromosome structure among cucumber cultivars occurred in the heterochromoatic region and suggested that the genetic variation in cucumber cultivars would be revealed by strict analysis and comparison for the position and size of heterochromatic region.

To resolve the discrepancy among previous karyotype descriptions, chromosome comparative study between two closely related cucumber cultivars, C. sativus L. cv. Borszczagowski and cv. Monastyrski, was performed by chromosome preparation technique with enzymatic maceration, and fluorescent banding method with chromomycin A3 (CMA) and 4′,6-diamidino-2-phenylindole (DAPI). Heterochromatic band polymorphisms were detected in chromosomes 2, 3, 5 and 7, whereas no chromosomal polymorphism was found in chromosomes 1, 4 and 6. In cv. Borszczagowski chromosome 2, CMA+DAPI+ heterochromatic band at terminal region of the long arm was smaller than that of cv. Monastyrski. Chromosome 3 of cv. Monastyrski was characterized by CMA+DAPI+ bands on the terminal regions of both arms, whereas that of cv. Borszczagowski displayed only on the terminal region of long arm. Distinct CMA+DAPI+ band located at terminal region of the long arm in cv. Borszczagowski was larger than that of cv. Monastyrski. In chromosome 7, terminal CMA+DAPI+ band at the short arm was only observed in cv. Monastyrski. This result suggested that inconsistency of karyotypes among previous reports was due to chromosomal polymorphism.

Zamia angustifolia, Z. integrifolia, Z. pumila and Z. pygmaea had the common chromosome number of 2n= 16 and the common karyotype which consisted of 12 median-, 2 submedianand 2 subterminal-centromeric chromosomes. The 4 species showed commonly the CMA-positive band in the centromeric region of 2 median-, 2 submedian-and 2 subterminal-centromeric chromosomes. In contrast, Z. furfuracea, Z. loddigesii, Z. skinneri and Z. vazquezii had commonly the chromosome number of 2n=18 and 10 median-and 2 submedian-centromeric chromosomes in karyotype but exhibited 6 different chromosomes from each other. Zamia furfuracea and Z. loddigesii displayed the CMA-positive band in the centromeric region of 8 median-and 6 acro-centromeric chromosomes. Zamia skinneri performed the CMA-positive band in the centromeric region of 4 acro-and 2 terminal-centromeric chromosomes, while Z. vazquezii performed the CMA-positive band in the centromeric region of 4 median-and 6 terminal-centromeric chromosomes. Zamia muricata had the chromosome number of 2n=23 differed from that of the previous count, the karyotype which consisted of 7 median-and 16 acro-centromeric chromosomes and the CMA-positive band in the centromeric region of 4 median-and 16 acro-centromeric chromosomes. Then, the 9 species of Zamia studied exhibited unclear DAPI-positive bands near the centromeric region of most of their chromosomes. By comparison, the closely related Ceratozamia mexicana had the chromosome number of 2n=16 and the CMA-positive band at the terminal region of 6 chromosomes.

Effects of the five macro-components and sucrose in half strength MS (1/2MS) agar medium on red-color pigmentation were studied in the plant bodies of Dionaea muscipula and Drosera spathulata generated from multiple shoots in vitro. In 1/2MS agar medium modified with 10.31mM NH4NO3 and 9.40mM KNO3 and supplemented with 0.75 or 0% sucrose the subcultured plants continuously proliferated by multiple shoots and generated large, green-colored plants, while with dilution of those nitrogen components and increase of sucrose to 1.5% the red-color anthocyanin pigmentation spread from the glands or glandular hairs to the entire leaves and the plant sizes and dry weight decreased in inverse proportion to the depth of red color. The anthocyanin pigments of Dionaea muscipula consisted of delphinidin 3-O-glucoside which was new to the species and cyanidin 3-O-glucoside (chrysanthemin), and those of Drosera spathulata, studied here for the first time, consisted of cyanidin 3, 5-di-O-glucoside (cyanin), cyanidin 3-O-galactoside (idaein), cyanidin 3-O-glucoside, pelargonidin 3-O-galactoside, and pelargonidin 3-O-glucoside (callistephin).

The chromosomal sites of 5S rDNA, 45S rDNA and Arabidopsis-iypt telomere sequence repeats characterize individual species and population constitutions in chrysanthemums and cycads and those of Sau3A in spruces. The sites of the telomere sequence repeats in the cycad chromosomes occur not only in the usual terminal regions of chromosome-arms as small dots, but also in several centromeric to proximal regions as relatively large signals. Large signals of the 278 bp DNA segment with respect to Cycas revoluta involved with pCrT7-4. The Y-chromosome of Cycas revoluta was distinct by lack of the large signal of pCrT7-4 and the Arabidopsis-type telomere sequence repeats. A highly conserved chromosomal location of these genes lead to speculation on the karyotype evolution and species property of the chrysanthemum and cycad groups.

Cucumber (Cucumis sativus L.), a widely cultivated crop, has originated from Eastern Himalayas and secondary domestication regions includes highly divergent climate conditions e.g. temperate and subtropical. We wanted to uncover adaptive genome differences between the cucumber cultivars and what sort of evolutionary molecular mechanisms regulate genetic adaptation of plants to different ecosystems and organism biodiversity. Here we present the draft genome sequence of the Cucumis sativus genome of the North-European Borszczagowski cultivar (line B10) and comparative genomics studies with the known genomes of: C. sativus (Chinese cultivar – Chinese Long (line 9930)), Arabidopsis thaliana, Populus trichocarpa and Oryza sativa. Cucumber genomes show extensive chromosomal rearrangements, distinct differences in quantity of the particular genes (e.g. involved in photosynthesis, respiration, sugar metabolism, chlorophyll degradation, regulation of gene expression, photooxidative stress tolerance, higher non-optimal temperatures tolerance and ammonium ion assimilation) as well as in distributions of abscisic acid-, dehydration- and ethylene-responsive cis-regulatory elements (CREs) in promoters of orthologous group of genes, which lead to the specific adaptation features. Abscisic acid treatment of non-acclimated Arabidopsis and C. sativus seedlings induced moderate freezing tolerance in Arabidopsis but not in C. sativus. This experiment together with analysis of abscisic acid-specific CRE distributions give a clue why C. sativus is much more susceptible to moderate freezing stresses than A. thaliana. Comparative analysis of all the five genomes showed that, each species and/or cultivars has a specific profile of CRE content in promoters of orthologous genes. Our results constitute the substantial and original resource for the basic and applied research on environmental adaptations of plants, which could facilitate creation of new crops with improved growth and yield in divergent conditions.