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Changnyeong, South Korea

Park J.,Chonnam National University | Cho D.Y.,ONBREETECH Corporation | Moon J.S.,Onion Research Institute | Yoon M.-K.,South Korean National Institute of Animal Science | Kim S.,Chonnam National University
Korean Journal of Horticultural Science and Technology | Year: 2013

Inactivation of the gene coding for dihydroflavonol 4-reductase (DFR) is responsible for the color difference between red and yellow onions (Allium cepa L.). Two inactive DFR-A alleles, DFR-APS and DFR-ADEL, were identified in our previous study. A functional marker was developed on the basis of the premature stop codon that inactivated the DFR-APS allele. A derived cleaved amplified polymorphic sequences (dCAPS) primer was designed to detect the single nucleotide polymorphism, an A/T transition, which produced the premature stop codon. Digested PCR products clearly distinguished the homozygous and heterozygous red F2 individuals. Meanwhile, to develop a molecular marker for detection of the DFR-ADEL allele in which entire DFR-A gene was deleted, genome walking was performed and approximately 3 kb 5' and 3' flanking sequences of the DFR-AR coding region were obtained. PCR amplification using multiple primers binding to the extended flanking regions showed that more of the extended region of the DFR-A gene was deleted in the DFR-ADEL allele. A dominant simple PCR marker was developed to identify the DFR-ADEL allele using the dissimilar 3' flanking sequences of the DFR-A gene and homologous DFR-B pseudogene. Distribution of the DFR-APS and DFR-ADEL alleles in yellow onion cultivars bred in Korea and Japan was surveyed using molecular makers developed in this study. Results showed predominant existence of the DFR-APS allele in yellow onion cultivars.

A field experiment was conducted to evaluate yield performance and soil fertility of onion (Allium cepa) grown with beef cattle manure compost (CMC) under a reduced rate of chemical fertilizer for sustainable production in the 2006-07 growing season. Chemical fertilizer application rate was reduced to a third of the recommended rate of nitrogen (N), phosphorus (P), and potassium (K). Treatments consisted of five levels of CMC (0, 20, 40, 60, and 80 Mg·ha-1). There was a significant increasing effect on growth and yield parameters by applying CMC compared with 0 Mg·ha-1. In addition, there was also a significant increasing quadratic effect on yield on increasing CMC rates from 0 to 80Mg·ha-1 with an R2 of 0.46. Maximum marketable yield was 62.7 Mg·ha-1 at 40 Mg·ha-1 CMC, which was due to increased stand reduction and unmarketable bulbs as well as decreased bulb weight at higher rates of CMC. The CMC rates had no effect on bulb dry weight and N or P concentration in the bulb and leaf. Furthermore, there was an increasing linear effect on soil pH, and organic matter (OM), available P, and exchangeable cations throughout vegetative growth and at harvest. We concluded that the excessive application of CMC did not affect onion yield and accumulated soil fertility.

Kwon Y.S.,South Korean National Institute of Animal Science | Kim C.W.,South Korean National Institute of Animal Science | Kim J.S.,Yeungnam University | Moon J.S.,Onion Research Institute | Yoo K.S.,Yeungnam University
Horticulture Environment and Biotechnology | Year: 2016

The growth of a flower stem (bolting) causes a decrease in yield and marketability in onion. We have examined the effects of bolting and of the removal of flower stems at different lengths on the growth and chemical qualities of onion bulbs. Two onion cultivars, ‘Mapshihwang’ (M) and ‘Yeongmihwang’ (Y), were grown in the field and allowed to bolt. The treatments included the removal of three different lengths of the flower stem (short, medium, or long), uncut flower stem until harvest, or unbolted plants (control). Bolting and the length of the flower stem removed had no effect on bulb diameter but caused a decrease in bulb weight. The flower stems were generated after three to five scales; bolting and flower stem removal reduced the number of scales by approximately one scale. The total soluble solid content (SSC) and the total sugar content were also unaffected by bolting and the length of the flower stem removed. The pungency of the M and Y cultivars, being an average of about 5.0 and 2.8 μmol·mL-1 pyruvic acid, respectively, was not changed. The total quercetin content showed various responses to the treatments and no clear differences compared to the unbolted bulbs. The total phenolic content was not changed by bolting or the stem removal treatments. In conclusion, bolting and removal of the flower stem caused a decrease in bulb weight, whereas the SSC, total sugar content, pungency, quercetin content, and total phenolic content remained unaffected, indicating that the chemical qualities of the bolted bulbs was identical to those of the unbolted, normal bulbs. The removal time of the flower stem had no significant difference on bulb quality. © 2016, Korean Society for Horticultural Science and Springer-Verlag GmbH.

This study was carried out to maximize the fertilization efficiency of mixed organic fertilizer (OF) for organically managed onion (Allium cepa L.) production during the one growing season of 2005-2006. The organic fertilizer was made of organic materials like sesame oil cake, rice bran and molasses and minerals like illite and mountainous soil. Four organic topdressing treatments, which all followed the same basal fertilization with solid OF, consisted of solid OF without mulch (OF/OFnM), liquid organic fertilizer without mulch (OF/LOFnM), liquid organic fertilizer under mulch (OF/LOFuM) and liquid organic fertilizer over mulch (OF/LOFoM). Chemical fertilizer (CF) and no fertilizer (NF) were treated as controls. The solid organic fertilization base was 2.0 ton ha-1, and 4.57 ton ha-1 and was used for topdressing. The total amount of liquid organic fertilization was 133.2 ton ha-1, which was divided into 6 applications from February through March. The OF/LOFuM and OF/LOFoM topdressings did not reduce onion height, leaf number or bulb diameter as compared to chemical fertilizer, whereas no mulch treatments made onion growth significantly poorer. Onion top weight in CF was significantly higher than that in OF groups at the peak growth stage, while there was not much difference in bulb weight between the CF and OF/LOFoM treatment. Finally, the onion marketable yield was 45.9 ton ha-1 in the OF/LOFoM treatment, which exceeded that in the CF treatment by up to 1.9 ton. Furthermore, OF/LOFoM was the most effective among all the treatments in transferring the nutrients from sink to source. CF made the soil pH more acidic than OF did, and the electrical conductivity (EC) remained higher with CF than OF as well. While organic fertilizer helped to keep the NO3-N content stable throughout the growing season, the concentration rapidly oscillated up and down according to CF fertilization. Organic fertilizer increased population number of soil microorganisms like aerobes, actinomycetes in the field. © 2010 Elsevier B.V. All rights reserved.

Song S.,Chonnam National University | Kim C.-W.,South Korean National Institute of Crop Science | Moon J.S.,Onion Research Institute | Kim S.,Chonnam National University
Molecular Breeding | Year: 2014

Inactivation of the gene (DFR-A) coding for dihydroflavonol 4-reductase (DFR) involved in the anthocyanin biosynthesis pathway results in a yellow bulb color in onion (Allium cepa L.). Three inactive alleles have previously been identified in onion, and in this study we identified three active and six inactive novel DFR-A alleles from extensive analyses of diverse onion germplasms. Of the germplasms analyzed, we identified a yellow mutant containing a 171-bp deletion in the promoter region, which we designated DFR-APD. Critically reduced transcription of this mutant allele and perfect co-segregation with color phenotypes in segregating populations were observed. A second yellow mutant (DFR-A5′DEL) which we identified contained a 518-bp deletion covering exons 1 and 2, which played important roles in DFR function. Both 2- and 4-bp insertions in the coding region leading to the creation of pre-mature stop codons were also identified and designated DFR-AGT and DFR-A2AT, respectively. A 1-bp substitution mutation (DFR-AK48N) which changed a positively charged lysine residue into a neutral asparagine was identified. This lysine residue, a NADPH binding site, was strictly conserved in other species. In addition, insertion of a leucine residue around substrate binding sites and catalytic triad was identified in several yellow accessions and designated DFR-ATTA. Phylogenetic analysis of DFR-A alleles showed that all inactive alleles were independently derived from four different active alleles. In addition, the close relatedness and diversity of DFR-A mutants implied that all these mutations might have occurred after domestication of onions and had probably been maintained by artificial selection. © 2013 Springer Science+Business Media Dordrecht.

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