Cytological analysis of the genome of cucumber [Cucumis sativus L.] and muskmelon [Cucumis melo L.]
01 Jan 1986-
About: The article was published on 1986-01-01 and is currently open access. It has received 40 citations till now. The article focuses on the topics: Cucumis.
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TL;DR: In this article, a high-density genetic map for Cucumis sativus was developed that contained 735 marker loci in seven linkage groups spanning 707.8 cM. Integration of genetic and physical maps resulted in a chromosomelevel draft genome assembly comprising 193 Mbp, or 53% of the 367 Mbp cucumber genome.
Abstract: Cucumber, Cucumis sativus L. is the only taxon with 2n = 2x = 14 chromosomes in the genus Cucumis. It consists of two cross-compatible botanical varieties: the cultivated C. sativus var. sativus and the wild C. sativus var. hardwickii. There is no consensus on the evolutionary relationship between the two taxa. Whole-genome sequencing of the cucumber genome provides a new opportunity to advance our understanding of chromosome evolution and the domestication history of cucumber. In this study, a high-density genetic map for cultivated cucumber was developed that contained 735 marker loci in seven linkage groups spanning 707.8 cM. Integration of genetic and physical maps resulted in a chromosome-level draft genome assembly comprising 193 Mbp, or 53% of the 367 Mbp cucumber genome. Strategically selected markers from the genetic map and draft genome assembly were employed to screen for fosmid clones for use as probes in comparative fluorescence in situ hybridization analysis of pachytene chromosomes to investigate genetic differentiation between wild and cultivated cucumbers. Significant differences in the amount and distribution of heterochromatins, as well as chromosomal rearrangements, were uncovered between the two taxa. In particular, six inversions, five paracentric and one pericentric, were revealed in chromosomes 4, 5 and 7. Comparison of the order of fosmid loci on chromosome 7 of cultivated and wild cucumbers, and the syntenic melon chromosome I suggested that the paracentric inversion in this chromosome occurred during domestication of cucumber. The results support the sub-species status of these two cucumber taxa, and suggest that C. sativus var. hardwickii is the progenitor of cultivated cucumber.
165 citations
TL;DR: The authors of this study assume that the novel cucumber reference genes determined will enable better normalization and quantification of transcript levels in future expression studies on cucumber plants.
Abstract: It has been shown that genes considered to be valid reference genes using semi-quantitative techniques (e.g. northern blot) appear to be less reliable when highly sensitive real-time PCR (qPCR) or microarrays are used. Therefore, the validation of expression stability of reference genes has become an important component of any study using such types of assay. No reference genes have been validated for expression studies of cucumber genes to date. Since the genome of this widely cultivated crop has been recently sequenced, the availability of suitable reference genes for expression analyses of the new cucumber genes is urgently required. For the purpose of normalization in studying expression of cucumber target genes, the stability of twelve reference genes in different cucumber tissues and under various stresses and growth regulators were determined in this study. These included commonly used cucumber reference genes, such as actin, EF, cyclophilin, ubiquitin and tubulin and the newly identified candidates for reference genes that encode clathrin adaptor complex subunit (CACS), F-box protein, PPA2 activator (tonoplast intrinsic protein, TIP41), mitosis protein (YSL8), protein phosphatase 2 (PDF2), helicase (HEL) and protein homolog of At4g33380. Analyses of quantitative real-time PCR data by three commonly used Excel-based applets, BestKeeper, geNorm and NormFinder, confirmed that expression stability of reference genes depends on the experimental parameters. In addition, they revealed that, except for EF, the most stable cucumber genes included mainly the new reference genes: CACS, F-box and TIP41, whereas the commonly used internal controls demonstrated various (actin, cyclophilin, ubiquitin) or much lower stability (tubulin). Hence, the authors of this study assume that the novel cucumber reference genes will enable better normalization and quantification of transcript levels in future expression studies on cucumber plants.
141 citations
Cites background from "Cytological analysis of the genome ..."
...…decades (Bhaduri and Bose 1947; Burzyński et al. 2005; Chen et al. 1998; Janicka-Russak et al. 2008; Koo et al. 2002; Migocka and Klobus 2007; Ramachandran and Seshadri 1986), whereas the analysis of cucumber genes, gene transcription and expression has grown only slowly, since most of the…...
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TL;DR: One hundred and ten markers were analysed for linkage in 218 F2 plants derived from two divergent cultivars of Cucumis melo, spanning 14 linkage groups covering 1390 cM of the melon genome.
Abstract: One hundred and ten markers were analysed for linkage in 218 F2 plants derived from two divergent cultivars (‘Vedrantais’ and ‘Songwhan Charmi’) of Cucumis melo (L.). Thirty-four RFLPs, 64 RAPDs, one isozyme, four disease resistance markers and one morphological marker were used to construct a genetic map spanning 14 linkage groups covering 1390 cM of the melon genome. RAPD and RFLP markers detected similar polymorphism levels. RFLPs were largely due to base substitutions rather than insertion/deletions. Twelve percent of markers showed distorted segregation. Phenotypic markers consisted of two resistance genes against Fusarium wilt (Fom-1 and Fom-2), one gene (nsv) controlling the resistance to melon necrotic spot virus, one gene (Vat) conferring resistance to Aphis gossypii, and a recessive gene for carpel numbers (3 vs 5 carpels: p).
128 citations
Cites background from "Cytological analysis of the genome ..."
...Meiotic analysis (Ramachandran and Seshadri 1986) revealed an average of 1....
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01 Jan 1993
TL;DR: The use of this vegetable is highlighted and its cytology, genetics, germplasm resources, and reproductive biology are reviewed and techniques applicable to the improvement of cucumber are described.
Abstract: Publisher Summary Cucumber, Cucumis sativus L., is a member of the Cucurbitaceae, which comprises 90 genera and 750 species. It is one of the oldest cultivated vegetable crops and is cultivated in nearly all countries of temperature zones. It is a thermophilic and frost-susceptible plant species, growing best at temperatures above 20 °C. This chapter highlights the use of this vegetable and reviews its cytology, genetics, germplasm resources, and reproductive biology. The taste and demands of the consumer varies according to country. Special varieties must be bred that set fruit under suboptimal temperature conditions. The demands of the processing industry concerning outer appearance—fruit shape, size, and color—also varies depending on the preservation process and the corresponding country. Therefore, cucumber breeders must consider several different breeding aims. General breeding objectives in cucumber are resistance to diseases and animal pests, maintenance of resistance in existing varieties, fruit quality, and fruit yield. Additionally, breeding aims such as parthenocarpy, constancy of femaleness, germination, and fruit set at suboptimum temperatures may be of importance in special breeding programs. Unlike many other plant species, there are different sex types in cucumber, which are of different value in breeding and concerning yield potential. By using sex inheritance and influencing sex expression, the breeding methods of self-pollinated and open-pollinated plants can be applied to cucumber. Thus, the cucumber breeder needs complete knowledge of sex inheritance and of potential ways of influencing sex expression. The chapter provides an overview of the selection of cucumber breeding methods and these methods. There have been several reports on the possibility of applying in vitro techniques in plant breeding of cucumber. The chapter describes techniques that are applicable to the improvement of cucumber.
128 citations
TL;DR: A 58-point genetic map was constructed with RFLP, RAPD, isozyme, morphological, and disease-resistance markers for a cross within the cultivated cucumber and the wild or feral C. hardwickii, agreeing with previous studies documenting a narrow genetic base for cucumber.
Abstract: A 58-point genetic map was constructed with RFLP, RAPD, isozyme, morphological, and disease-resistance markers spanning 766 cM on ten linkage groups for a cross within the cultivated cucumber (Cucumis sativus var. sativus). Relatively few DNA polymorphisms were detected, agreeing with previous studies documenting a narrow genetic base for cucumber. Most RFLPs within the cultivated cucumber appear to be changes at restriction-enzyme sites. Sixty-four percent of RAPD markers that fit expected ratios at P<0.001 were unlinked, possibly due to poor amplification and the inefficiency of dominant markers to detect linkage in an F2 family. A 70-point linkage map, spanning 480 cM on ten linkage groups, was constructed with RFLP, isozyme, morphological, and diseaseresistance markers for a cross between the cultivated cucumber and the wild or feral C. sativus var. hardwickii. Unlinked markers and more linkage groups than chromosome pairs indicated that both maps were not saturated. Twentyone markers doubly segregated in both families and regions of colinearity were identified.
114 citations