Rapid divergence of repetitive DNAs in Brassica relatives.

Centromeric, subtelomeric, and telomeric repetitive DNAs were characterized in Brassica species and the related Raphanus sativus and Arabidopsis thaliana. In general, rapid divergence of the repeats was found. The centromeric tandem satellite repeats were differentially distributed in the species studied, suggesting that centromeric repeats have diverged during the evolution of the A/C and B genome lineages.

Sweetpotato late embryogenesis abundant 14 (IbLEA14) gene influences lignification and increases osmotic- and salt stress-tolerance of transgenic calli.

Late embryogenesis abundant 14 (LEA14) cDNA was isolated from an EST library prepared from dehydration-treated fibrous roots of sweetpotato (Ipomoea batatas). Quantitative RT-PCR revealed a variety of different IbLEA14 expression patterns under various abiotic stress conditions. IbLEA14 expression was strongly induced by dehydration, NaCl and abscisic acid treatments in sweetpotato plants.

Molecular cytogenetic mapping of Cucumis sativus and C. melo using highly repetitive DNA sequences.

Chromosomes often serve as one of the most important molecular aspects of studying the evolution of species. Indeed, most of the crucial mutations that led to differentiation of species during the evolution have occurred at the chromosomal level. Furthermore, the analysis of pachytene chromosomes appears to be an invaluable tool for the study of evolution due to its effectiveness in chromosome identification and precise physical gene mapping.

Integration of cytogenetic and genetic linkage maps unveils the physical architecture of tomato chromosome 2.

We report the integration of the linkage map of tomato chromosome 2 with a high-density bacterial artificial chromosome fluorescence in situ hybridization (BAC-FISH)-based cytogenetic map. The euchromatic block of chromosome 2 resides between 13 and 142 cM and has a physical length of 48.12 microm, with 1 microm equivalent to 540 kb.

Extensive chromosomal polymorphism revealed by ribosomal DNA and satellite DNA loci in 13 Citrus species.

Little is known about the chromosomal variability and polymorphism existing in mitotic chromosomes of Citrus, mainly due to lack of reliable chromosomal markers and small chromosome size. To test the hypothesis of chromosomal polymorphism and provide the foundation of the genome organization in the Citrus cultivars, we have developed molecular cytogenetic markers for 13 Citrus species collected from Jeju island, Korea. In this study, we demonstrated that the chromosomal locations of cytogenetic markers are quite variable and extremely polymorphic, in contrast to the previous studies.

Molecular cloning of peroxidase cDNAs from dehydration-treated fibrous roots of sweetpotato and their differential expression in response to stress.

Three peroxidase (POD) cDNAs were isolated from dehydration-treated fibrous roots of sweetpotato (Ipomoea batatas) plant via the screening of a cDNA library, and their expressions were assessed to characterize functions of each POD in relation to environmental stress. Three PODs were divided into two groups, designated the basic PODs (swpb4, swpb5) and the anionic PODs (swpa7), on the basis of the pI values of mature proteins. Fluorescence microscope analysis indicated that three PODs are secreted into the extracellular space.

Overexpression of sweetpotato swpa4 peroxidase results in increased hydrogen peroxide production and enhances stress tolerance in tobacco.

Plant peroxidases (POD) reduce hydrogen peroxide (H(2)O(2)) in the presence of an electron donor. Extracellular POD can also induce H(2)O(2) production and may perform a significant function in responses to environmental stresses via the regulation of H(2)O(2) in plants. We previously described the isolation of 10 POD cDNA clones from cell cultures of sweetpotato (Ipomoea batatas).

Molecular characterization of a cDNA encoding DRE-binding transcription factor from dehydration-treated fibrous roots of sweetpotato.

A new dehydration responsive element-binding (DREB) protein gene encoding for an AP2/EREBP-type transcription factor was isolated by screening of the cDNA library for dehydration-treated fibrous roots of sweetpotato (Ipomoea batatas). Its cDNA (referred to as swDREB1) fragment of 1206bp was sequenced from, which a 257 amino acid residue protein was deduced with a predicted molecular weight of 28.17kDa.

Differential expression of 10 sweetpotato peroxidases in response to sulfur dioxide, ozone, and ultraviolet radiation.

Secretory class III plant peroxidase (POD, EC 1.11.1.

The reference genetic linkage map for the multinational Brassica rapa genome sequencing project.

We describe the construction of a reference genetic linkage map for the Brassica A genome, which will form the backbone for anchoring sequence contigs for the Multinational Brassica rapa Genome Sequencing Project. Seventy-eight doubled haploid lines derived from anther culture of the F(1) of a cross between two diverse Chinese cabbage (B. rapa ssp.

Suppression of RICE TELOMERE BINDING PROTEIN 1 results in severe and gradual developmental defects accompanied by genome instability in rice.

Although several potential telomere binding proteins have been identified in higher plants, their in vivo functions are still unknown at the plant level. Both knockout and antisense mutants of RICE TELOMERE BINDING PROTEIN1 (RTBP1) exhibited markedly longer telomeres relative to those of the wild type, indicating that the amount of functional RTBP1 is inversely correlated with telomere length. rtbp1 plants displayed progressive and severe developmental abnormalities in both germination and postgermination growth of vegetative organs over four generations (G1 to G4).

Enhanced tolerance to oxidative stress in transgenic tobacco plants expressing three antioxidant enzymes in chloroplasts.

The effect of simultaneous expression of genes encoding three antioxidant enzymes, copper zinc superoxide dismutase (CuZnSOD, EC 1.15.1.

A Survey of the Brassica rapa genome by BAC-end sequence analysis and comparison with Arabidopsis thaliana.

Brassica rapa ssp. pekinensis (Chinese cabbage) is an economically important crop and a model plant for studies on polyploidization and phenotypic evolution. To gain an insight into the structure of the B.

Depletion of UDP-D-apiose/UDP-D-xylose synthases results in rhamnogalacturonan-II deficiency, cell wall thickening, and cell death in higher plants.

D-apiose serves as the binding site for borate cross-linking of rhamnogalacturonan II (RG-II) in the plant cell wall, and biosynthesis of D-apiose involves UDP-D-apiose/UDP-D-xylose synthase catalyzing the conversion of UDP-D-glucuronate to a mixture of UDP-D-apiose and UDP-D-xylose. In this study we have analyzed the cellular effects of depletion of UDP-D-apiose/UDP-D-xylose synthases in plants by using virus-induced gene silencing (VIGS) of NbAXS1 in Nicotiana benthamiana. The recombinant NbAXS1 protein exhibited UDP-D-apiose/UDP-D-xylose synthase activity in vitro.

A high-resolution karyotype of cucumber (Cucumis sativus L. 'Winter Long') revealed by C-banding, pachytene analysis, and RAPD-aided fluorescence in situ hybridization.

Using molecular cytogenetic DNA markers, C-banding, pachytene analysis, and fluorescence in situ hybridization (FISH), a high-resolution karyotype was established in the cucumber. C-banding showed distinct hetero chromatic bands on the pericentromeric, telomeric, and intercalary regions of the chromosomes. The C-banding patterns were also consistent with the morphology of 4'-6-diamino-2-phenylindole dihydrochloride (DAPI)-stained pachytene chromosomes.

Characterization of rDNAs and tandem repeats in the heterochromatin of Brassica rapa.

We describe the morphology and molecular organization of heterochromatin domains in the interphase nuclei, and mitotic and meiotic chromosomes, of Brassica rapa, using DAPI staining and fluorescence in situ hybridization (FISH) of rDNA and pericentromere tandem repeats. We have developed a simple method to distinguish the centromeric regions of mitotic metaphase chromosomes by prolonged irradiation with UV light at the DAPI excitation wavelength. Application of this bleached DAPI band (BDB) karyotyping method to the 45S and 5S rDNAs and 176 bp centromere satellite repeats distinguished the 10 B.

Functional characterization of NtCEF1, an AP2/EREBP-type transcriptional activator highly expressed in tobacco callus.

Using PCR-select cDNA subtraction, we identified the genes that are predominantly expressed in the shooty callus induced by suppression of the CHRK1 receptor-like kinase gene. One of the identified genes encoded a novel AP2/EREBP-type transcription factor, and it was highly expressed in various types of tobacco callus including the CHRK1 transgenic callus, hence designated as Nicotiana tabacum Callus-Expressing Factor 1 NtCEF1. The NtCEF1-GFP fusion protein was localized in the nucleus.

A high-resolution karyotype of Brassica rapa ssp. pekinensis revealed by pachytene analysis and multicolor fluorescence in situ hybridization.

A molecular cytogenetic map of Chinese cabbage (Brassica rapa ssp. pekinensis, 2 n=20) was constructed based on the 4'-6-diamino-2-phenylindole dihydrochloride-stained mitotic metaphase and pachytene chromosomes and multicolor fluorescence in situ hybridization (McFISH), using three repetitive DNA sequences, 5S rDNA, 45S rDNA, and C11-350H. The lengths of mitotic metaphase chromosomes ranged from 1.

Characterization of the plastid-encoded carboxyltransferase subunit (accD) gene of potato.

The plastid accD gene encoding the carboxyltransferase b subunit of acetyl-coenzyme A carboxylase (ACCase) was cloned from potato. Potato accD (saccD) is 2487 bp in length with a 614 bp 5 cent upstream promoter region and an ORF of 1524 bp, corresponding to a polypeptide of 507 amino acids. The N-terminal region lacks recognizable motifs, while the C-terminal regions contains five motifs.

Construction of a garlic BAC library and chromosomal assignment of BAC clones using the FISH technique.

For molecular and cytogenetic studies, two partial bacterial artificial chromosome (BAC) libraries of the garlic cultivar Allium sativum L. 'Danyang' were constructed using high molecular weight (HMW) garlic DNA, the pBAC1-SACB1 vector, and the pIndigoBAC536 vector. The average insert size of the BAC library was about 90 kb.

A novel oxidative stress-inducible peroxidase promoter from sweetpotato: molecular cloning and characterization in transgenic tobacco plants and cultured cells.

A strong oxidative stress-inducible peroxidase (POD) promoter was cloned from sweetpotato (Ipomoea batatas) and characterized in transgenic tobacco plants and cultured cells in terms of environmental stress. A POD genomic clone (referred to as SWPA2) consisted of 1824 bp of sequence upstream of the translation start site, two introns (743 bp and 97 bp), and a 1073 bp coding region. SWPA2 had previously been found to encode an anionic POD which was highly expressed in response to oxidative stress.

Karyotype analysis of a Korean cucumber cultivar (Cucumis sativus L. cv. Winter Long) using C-banding and bicolor fluorescence in situ hybridization.

An intensive karyotype analysis of a Korean cucumber cultivar (Cucumis sativus L. cv. Winter Long) was carried out with three different methods.