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Application of Genome Editing Nucleases to Crop Breeding
Geung-Joo Lee,Heon-Joong Kim,Seokjoong Kim,Gabbin Wee,Jin-Soo Kim 한국육종학회 2012 한국육종학회 심포지엄 Vol.2012 No.07
Reliable and precise techniques for targeting modification of plant genomes have been explored in plant breeding communities. Initiated in the animal genome first, now the genome editing tool using a nuclease has been reported in some plant species including Arabidopsis, Maize, Tobacco, and other model systems. When the artificial nuclease is introduced into a plant cell and breaks the genomic sites randomly, endogenously operating DNA-repair mechanisms including non-homologous end joining(NHEJ) or homologous recombination(HR) are anticipated, leading to insertion of foreign DNA or deletion of the target locus, which collectively allows changes in plant traits of interest. Traditionally custom designed for induction of double-strand DNA break(DSB) at a predetermined locus was based on zinc-finger nuclease which contains nonspecific cleavage domains with target specificities of DNA binding zinc finger domains(three to four). The binding domains containing more than 20 DNA bases with high affinity to the target gene enable recognition of the locus efficiently. From this project, we focus on a petunia chalcone synthase(CHS) as a model system. The engineered nuclease will target the CHS gene, which is expected to be modified either constitutely or transiently. The derived transformed plants will be genetically or phenotypicly screened, along with molecular confirmation analysis by using various tools. We eventually extend the tools to various crop species and target genes, which makes the brand-new breeding technique more reliable and robust.
Biomass and Molecular Characteristics of Multi-tillering Miscanthus Mutants
Lee, Geung-Joo,Zhang, Lili,Choi, Young In,Chung, Sung Jin,Yoo, Yong Kweon,Kim, Dong Sub,Kim, Sang Hoon The Plant Resources Society of Korea 2012 한국자원식물학회지 Vol.25 No.6
Compared to wide ranges of genetic variation of natural populations, very limited Miscanthus cultivar has been released. This study was the first report on the development of Miscanthus cultivar by means of radiation breeding. Seeds of M. sinensis were initially exposed to gamma rays of 250 Gy for 24 h, generated from a $^{60}Co$ gamma-irradiator. The irradiated seeds were sown and then the highly tiller-producing mutants were selected for this study. Biomass-related parameters including tiller number, plant height, stem diameter, and leaf number were measured. Ploidy level and internal transcribed spacer (ITS) were investigated to characterize the mutants compared to wild type (WT) Miscanthus. Plant height and tiller number were negatively related, where multi-tillering mutants were relatively short after 4 month growth. However stem diameter and leaf number were greater in mutants. All the materials used in this study were diploid, implying that the mutants with greater tiller numbers and stem diameter were not likely related to polyploidization. Based on the sequence of ITS regions, the mutants demonstrated base changes from the gamma irradiation where G+C content (%) was decreased in the ITS1, but increased in ITS2 when compared to WT sequence. ITS2 region was more variable than in ITS1 in the mutants, which collectively allows identification of the mutants from WT. Those mutants having enhanced tillers and allelic variations might be used as breeding materials for enhanced biomass-producing Miscanthus cultivars.
Lee, Sun-Joo,Kim, Woo Young,Lee, Jeong-Won,Kim, Hyoung Sun,Choi, Yoon-La,Ahn, Geung Hwan,Lee, Je-Ho,Kim, Byoung-Gie,Bae, Duk-Soo BMJ 2009 International journal of gynecological cancer Vol.19 No.3
<B>Objective:</B><P>This study was performed to evaluate the efficacy and feasibility of electrosurgical conization and cold coagulation as definitive treatments for patients with International Federation of Gynecology and Obstetrics stage IA1 squamous cell carcinoma of the cervix and a resection margin free from (micro)invasive carcinoma after conization.</P><B>Methods:</B><P>Patients with stage IA1 cervical squamous cell carcinoma without lymphovascular space invasion who had been treated by electrosurgical conization and cold coagulation and who wanted to preserve fertility (or only undertake conservative treatment) were followed up without further surgical intervention. Patients with invasive or microinvasive carcinoma at resection margins or positive endocervical resection margins were excluded from the study. Cervicovaginal smears and colposcopic examination were performed at regular intervals. Disease recurrence was defined as a histologic diagnosis of cervical intraepithelial neoplasia 2 or higher-grade lesions.</P><B>Results:</B><P>A total of 85 patients enrolled were deemed eligible to be involved in the study. The median follow-up period was 81.0 months (range, 13-127 months). Nineteen of the 85 patients had exocervical resection margins. There was one case of recurrence, which was node-positive invasive cancer recurrence (1.2%, 1/85), in patients with negative resection margins.</P><B>Conclusions:</B><P>These results suggest that electrosurgical conization with cold coagulation is a feasible treatment and could be used as a definitive therapy for patients with stage IA1 cervical squamous cell carcinoma without lymphovascular space invasion. In addition, patients having cervical intraepithelial neoplasias 2 and 3 at exocervical resection margins could be followed up carefully without further treatment after conization and cold coagulation.</P>