Soo-Seong Lee

Developing stable progenies of ×Brassicoraphanus, an intergeneric allopolyploid between Brassica rapa and Raphanus sativus, through induced mutation using microspore culture.

Induced mutations were used to improve the low seed fertility of an intergeneric allopolyploid, ‘Baemoochae,’ ×Brassicoraphanus, synthesized following hybridization between Brassicarapa and Raphanus sativus. The mutagen N-methyl-N-nitroso-urethane (NMU) was added to microspore cultures. Four lines of nine in the Mi2 generation showed very high fertility under controlled pollination. The progeny lines (Mi3) confirmed this result under open pollination, and excellent uniformity was observed in plants grown in the field, as well as in their AFLP profile. On attaining high fertility and uniformity, one of the lines was released to farmers as a new leafy vegetable crop. The original nine lines shared very similar AFLP banding patterns, without any large differences between the high and low seed fertility lines. Thus, mutation induction accelerated genetic stabilization of a newly synthesized allopolyploid, ×Brassicoraphanus.

Screening of gamma irradiated spices in Korea by using a microbiological method (DEFT/APC)

Irradiation can be used to control the microbiological spoilage and pathogen microorganisms of foods. Microbiological changes associated with food irradiation include the reduction or elimination of spoilage and pathogenic microorganisms, insect disinfestation and parasite disinfection. The effects on the microbial populations of irradiated foods have been used to develop detection methods for irradiated foods. The method used in this study was direct epifluorescent filter technique/aerobic plate count (DEFT/APC), which is based on the difference between DEFT counts and APC counts. The samples were imported spices and domestic spices produced in Korea. These samples were irradiated at 1.0, 3.0, 5.0, 7.0, and 10 kGy to reduce the spoilage organisms. Irradiation doses of 3.0 kGy or over eliminated viable microorganisms effectively, and the logDEFT/APC ratio gradually increased with dose increment in all the samples. It could be suggested that if the logDEFT/APC ratio is 2.5 or over for peppers in Korea, the samples can be suspected as irradiated at a dose level of at least 3.0 kGy. The DEFT/APC method could be used for screening for the irradiation treatment of spices produced in Korea.

Development of a leafy Brassica rapa fixed line collection for genetic diversity and population structure analysis

Brassica rapa is an economically important crop with a wide range of morphologies. Developing a set of fixed lines and understanding their diversity has been challenging, but facilitates resource conservation. We investigated the genetic diversity and population structure of 238 fixed lines of leafy B. rapa with 45 new simple sequence repeat markers and 109 new NGS (next-generation sequencing)-generated single nucleotide polymorphism markers evenly distributed throughout the B. rapa genome. Phylogenetic analysis classified the vegetable fixed lines into four subgroups, with the three oil types forming a separate and relatively distant cluster. A model-based population structure analysis identified four subpopulations corresponding to geographical origins and morphological traits, and revealed extensive allelic admixture. In particular, the Chinese cabbage cluster was subdivided into three groups and showed considerable correlation with leaf- and heading-related traits (leaf and heading shape). The vegetable B. rapa fixed lines successfully developed in our study could be valuable materials for establishing a multinational Brassica rapa diversity resource. Understanding the genetic diversity and population structure could be useful for utilization of the representative genetic variation and further genomic analysis.

Identification of monogenic dominant male sterility and its suppressor gene from an induced mutation using a broccoli (Brassica oleracea var. italica) microspore culture

Male sterility (MS) has been studied intensively in Brassica crops to ensure high purity and the protection of F1 hybrids. In the preceding trial, broccoli microspores were treated with a mutagen, n-nitroso-n-methyl urethane (NMU), during the cultural process to produce MS. Many MS plants were derived from the 0.01 μM and 0.1 μM treatments just before and at the fourth day of culture, respectively. In this study, most MS plants inherited sterility from a single recessive gene. Only one plant, 9-4C-106, which originated from the 0.1 μM treatment on the fourth day, was controlled by a single dominant gene. Another dominant mutant gene suppressing the expression of this dominant MS gene was discovered in a plant treated with 0.01 μM NMU. A hybrid breeding system using this MS structure is discussed.

Characterization of self-incompatibility genes in the intergeneric hybrid xBrassicoraphanus

Brassica rapa and Raphanus sativus are strictly self-incompatible (SI) plants; however, xBrassicoraphanus (baemoochae) is an intergeneric hybrid synthesized following hybridization of B. rapa and R. sativus that is self-compatible (SC). Self-incompatibility in Brassicaceae is controlled by multiple alleles of the S-locus. Two S-locus genes, SRK (S-locus receptor kinase) and SP11/SCR (S-locus protein 11 or S-locus cysteine-rich), have been reported to date, both of which are classified into class I and II. In this study, we investigate if there is an alteration in the structure or the expression in SRK or SP11 genes behind the alteration of SI to SC in baemoochae. Class I and II SRK were identified by PCR of the genomic DNA of baemoochae using SRK-specific universal primers. Cloning and sequencing of both classes of SRK was conducted and compared with SRK genes of parental species. Comparison analysis showed no genomic alterations and both of them showed expression in the stigma. Similarly, SP11 genes also showed no genomic alterations and normally are expressed in the anther. Other SI-related genes (MLPK, ARC1, THL) also showed normal expression in the stigma and anther. Taken together, these results revealed that no structural/gene expression change in these genes was responsible for the breakdown of SI in baemoochae. Rather, the transformation from SI parents to SC descendants could be responding to epigenetic mechanisms.

P04.10: Frontomaxillary facial angle in chromosomally normal Korean population at 11 + 0 to 13 + 6 weeks

Objectives: To determine whether absent flow during atrial contraction in the Doppler velocimetry of the ductus venosus can improve the predictive capacity of this method in the detection of Down syndrome at 11–14 weeks of gestation. Methods: Ductus venosus Doppler ultrasound blood velocity waveforms were obtained prospectively at 11–14 weeks of gestation in 2495 consecutive singleton pregnancies. In the first group waveforms were classified either as normal in the presence of a positive A-wave, or as abnormal if the A-wave was absent or negative. In the second group, waveforms were classified as abnormal if only A-wave was negative (reverse flow). All cases were screened for chromosomal defects by a combination of maternal age and fetal nuchal translucency thickness. Results: Down syndrome was found in 39 cases. In the first group the flow was abnormal in 30 cases, the overall detection rate, specificity, positive predictive value, negative predictive value and likelihood ratio for trissomy 21 were 76.9%, 99.0%, 54.5%, 99.6% and 75.5 respectively. On basis in the ductus venosus blood flow during atrial contraction as positive marker only A-wave was negative (24 cases) the sensitivity, specificity, the positive and negative predictive values and likelihood ratio were 61.5%, 99.1%, 53.3%, 99.4%, 71.9 respectively. Conclusions: Abnormal ductus venosus blood flow is an useful marker of Down syndrome in the first trimester ultrasound screening. We could improve the predictive for the detection of trisomy 21, and consequently becoming an excellent marker, by considering absent flow during atrial contraction as a positive marker (abnormal). Screening for Down syndrome in Brazil presents comparable results to those in other countries. It is a method of clinical applicability in any part of the world.