• Mycobiology
• /
• 제46권2호
• /
• pp.172-176
• /
• 2018

A new species belonging to the genus Alternaria was isolated from the necrotic leaf spots of Brassica rapa subsp. pekinensis in Yuseong district, Daejeon, Korea. It is an occasional isolate, not an etiological agent, which is morphologically similar to A. broccoli-italicae, but differs in conidial size and conidiophore shape. Phylogenetic analysis using the sequence datasets of the internal transcribed spacer (ITS) region of the rDNA, glyceraldehyde-3-phosphate dehydrogenase (gpd), and plasma membrane ATPase genes showed that it is distantly related to A. broccoli-italicae and closely related to Alternaria species in the section Pseudoalternaria, which belonged to a clade basal to the section Infectoriae. Morphologically, the species is unique because it produces solitary conidia or conidial chains (two units), unlike the four members in the section Pseudoalternaria that produce conidia as short branched chains. It exhibits weak pathogenicity in the host plant. This report includes the description and illustration of A. brassicifolii as a new species.

• Journal of Plant Biology
• /
• 제5권3호
• /
• pp.21-24
• /
• 1962

Intergeneric crossings between the inbred line of Brassica pekinensis var. Chongbangkokun and inbred line of Raphanus sativus var. Oolsanjaelae were made using Brassica as female plant, and obtained two individuals of intergeneric hybrids. Morphological characters of the two F1 hybrids are mostly intermediate of the two parental species, and their somatic chromosome number is 19. Meiotic behaviors of the parental plants were normal, while those of F1 plants were extremely irregular. The mean pairing frequencies per cell of hybrids are 1.09II＋16.811(examined in May), and 1.76II＋15.47i(examined in June). Majority of the pollen grain of parent species are normal, whereas those of F1's are invariably abortive. No seed setting was obtained in the hybrid plants left in the open field.

• Plant Resources
• /
• 제8권3호
• /
• pp.286-292
• /
• 2005

Shoot induction system was developed in the recalcitrant plant species, Brassica rapa ssp. rapifera by using optimum selection of profit organ, phytohormone combination, seedling age and kind of culture container. Out of in vitro cultured leaf segment, petiole, hypocotyl, and cotyledon with petiole, only cotyledon with petiole derived from 4 day-old seedlings induced multiple shoot. The optimum combination of auxin and cytokinin for the multiple shoot induction was MS medium containing 5mg/L BA and 0.5mg/L NAA. The major factors for multiple shoot propagation were part of plant organ, age of seedling, and ratio of auxin and cytokinin. In addition, shoot regeneration was promoted in the 100ml Erlenmeyer flask compared with the $90mm{\times}20mm$ Petri-dish. The induced shoots formed roots easy on MS medium containing 0.1mg/L IBA and the whole plants were successfully cultivated in soil.

• Journal of Plant Biotechnology
• /
• 제39권1호
• /
• pp.1-12
• /
• 2012

With the increasing advances in Brassicaceae genetics and genomics, considerable progress has been made in the transformation of Brassicaceae. Transformation technologies are now being exploited routinely to determine the gene function and contribute to the development of novel enhanced crops. $Agrobacterium$-mediated transformation remains the most widely used approach for the introduction of transgenes into Brassicaceae. In $Brassica$, the transformation relies mainly on $in$ $vitro$ transformation methods. Nevertheless, despite the significant progress made towards enhancing the transformation efficiencies, some genotypes remain recalcitrant to transformation. Advances in our understanding of the genetics behind various transformations have enabled researchers to identify more readily transformable genotypes for use in routine high-throughput systems. These developments have opened up exciting new avenues to exploit model $Brassica$ genotypes as resources for understanding the gene function in complex genomes. Although many other Brassicaceae have served as model species for improving plant transformation systems, this paper summarizes on the recent technologies employed in the transformation of both $Arabidopsis$ and $Brassica$. The use of transformation technologies for the introduction of desirable traits and a comparative analysis of these as well as their future prospects are also important parts of the current research that is reviewed.

• Journal of Plant Biotechnology
• /
• 제37권2호
• /
• pp.186-195
• /
• 2010

In most self-incompatible plant species, recognition of self-pollen is controlled by a single locus, termed the S-locus. The self-incompatibility (SI) system in Brassica is controlled sporophytically by multiple alleles at a single locus, designated as S, and involves cell-cell communication between male and female. Two highly polymorphic S locus genes, SLG (S locus glycoprotein) and SRK (S receptor kinase), have been identified, both of which are expressed predominantly in the stigmatic papillar cell. Gain-of-function experiments have demonstrated that SRK solely determines S haplotype-specificity of the stigma, while SLG enhances the recognition reaction of SI. The sequence analysis of the S locus genomic region of B. campestris (syn. rapa) has led to the identification of an anther-specific gene, designated as SP11/SCR, which is the male S determinant. Molecular analysis has demonstrated that the dominance relationships between S alleles in the stigma were determined by SRK itself, but not by the relative expression level. In contrast, the expression of SP11/SCR from the recessive S allele was specifically suppressed in the S heterozygote, suggesting that the dominance relationships in pollen were determined by the expression level of SP11/SCR. Furthermore, recent studies on recessive allele-specific DNA methylation of Brassica self-incompatibility alleles demonstrate that DNA methylation patterns in plants can vary temporally and spatially in each generation. In this review, we firstly present overview of self incompatibility system in Brassica and then describe dominance relationships in Brassica self- incompatibility regulated by allele-specific DNA methylation.

• Molecules and Cells
• /
• 제23권3호
• /
• pp.349-356
• /
• 2007

Simple Sequence Repeats (SSRs) represent short tandem duplications found within all eukaryotic organisms. To examine the distribution of SSRs in the genome of Brassica rapa ssp. pekinensis, SSRs from different genomic regions representing 17.7 Mb of genomic sequence were surveyed. SSRs appear more abundant in non-coding regions (86.6%) than in coding regions (13.4%). Comparison of SSR densities in different genomic regions demonstrated that SSR density was greatest within the 5'-flanking regions of the predicted genes. The proportion of different repeat motifs varied between genomic regions, with trinucleotide SSRs more prevalent in predicted coding regions, reflecting the codon structure in these regions. SSRs were also preferentially associated with gene-rich regions, with peri-centromeric heterochromatin SSRs mostly associated with retrotransposons. These results indicate that the distribution of SSRs in the genome is non-random. Comparison of SSR abundance between B. rapa and the closely related species Arabidopsis thaliana suggests a greater abundance of SSRs in B. rapa, which may be due to the proposed genome triplication. Our results provide a comprehensive view of SSR genomic distribution and evolution in Brassica for comparison with the sequenced genomes of A. thaliana and Oryza sativa.

• Journal of Plant Biotechnology
• /
• 제3권1호
• /
• pp.27-31
• /
• 2001

New types of cytoplasmic male sterility in Brassica species would be very useful for the production of F$_1$, hybrid seeds. Leaves and stems of rapid cycling stock of B.juncea (CrGC4-3) containing Anand CMS were used as experimental materials for plant regeneration from protoplast culture. Very high plant regeneration rate (85%) was found in the Kao & Michayluk medium supplemented with 2 mg/L zeatin, 0.5 mg/L BAP, and 1 mg/L NAA when only leaf, not stem, segments were cultured. Protoplasts were isolated from leaves using mixtures of enzymes (1% Cellulycin, 0.5% Macerozyme) in 0.4 M mannitol and 50 mM $CaCl_2$.$2H_2$O. Mcrocalli induced from protoplasts were transferred to the shoot regeneration medium containing 2 mg/L BAP, 2 mg/L zeatin, and 0.5 mg/L NAA. After 60 days of initial protoplast culture, regenerated plantlets were obtained, acclimatized, transplanted into the pots, and grown up to the flowering stage.

• Genomics & Informatics
• /
• 제15권4호
• /
• pp.128-135
• /
• 2017

As next-generation sequencing technologies have advanced, enormous amounts of whole-genome sequence information in various species have been released. However, it is still difficult to assemble the whole genome precisely, due to inherent limitations of short-read sequencing technologies. In particular, the complexities of plants are incomparable to those of microorganisms or animals because of whole-genome duplications, repeat insertions, and Numt insertions, etc. In this study, we describe a new method for detecting misassembly sequence regions of Brassica rapa with genotyping-by-sequencing, followed by MadMapper clustering. The misassembly candidate regions were cross-checked with BAC clone paired-ends library sequences that have been mapped to the reference genome. The results were further verified with gene synteny relations between Brassica rapa and Arabidopsis thaliana. We conclude that this method will help detect misassembly regions and be applicable to incompletely assembled reference genomes from a variety of species.

• Journal of Plant Biotechnology
• /
• 제39권1호
• /
• pp.13-22
• /
• 2012

Plant regeneration has been optimized increasingly by organogenesis and somatic embryogenesis using a range of explants with tissue culture improvements focusing on factors, such as the age of the explant, genotype, media supplements and $Agrobacterium$ co-cultivation. The production of haploids and doubled haploids using microspores has accelerated the production of homozygous lines in Brassicaceae crop plants. Somatic cell fusion has facilitated the development of interspecific and intergeneric hybrids in sexually incompatible species of $Brassica$. Crop improvement using somaclonal variation has also been achieved. Transformation technologies are being exploited routinely to elucidate the gene function and contribute to the development of novel enhanced crops. The $Agrobacterium$-mediated transformation is the most widely used approach for the introduction of transgenes into Brassicaceae, and $in$ $vitro$ regeneration is a key factor in developing an efficient transformation method in plants. Although many other Brassicaceae are used as model species for improving plant regeneration and transformation systems, this paper focuses on the recent technologies used to regenerate the most important Brassicaceae crop plants.

• Molecules and Cells
• /
• 제22권3호
• /
• pp.300-307
• /
• 2006

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. rapa genome we analyzed 12,017 BAC-end sequences for the presence of transposable elements (TEs), SSRs, centromeric satellite repeats and genes, and similarity to the closely related genome of Arabidopsis thaliana. TEs were estimated to occupy 14% of the genome, with 12.3% of the genome represented by retrotransposons. It was estimated that the B. rapa genome contains 43,000 genes, 1.6 times greater than the genome of A. thaliana. A number of centromeric satellite sequences, representing variations of a 176-bp consensus sequence, were identified. This sequence has undergone rapid evolution within the B. rapa genome and has diverged among the related species of Brassicaceae. A study of SSRs demonstrated a non-random distribution with a greater abundance within predicted intergenic regions. Our results provide an initial characterization of the genome of B. rapa and provide the basis for detailed analysis through whole-genome sequencing.