Brown planthopper (BPH) is a destructive insect pest of rice in Korea. Identification and the incorporation of newBPH resistance genes into modern rice cultivars are important breeding strategies to control the damage caused by BPH. To expand genetic resource against BPH in Korea, we screened more than 2,500 mutant lines, which were derived from EMS treatment on Namil, a high yielding Korean japonica cultivar. One mutant line, Namil(EMS)M2-1463-1-1-1-1, designated as ‘Namil(EMS)-bl10,bph1’ performed high level of resistance against BPGH and rice blast, while the wild type, Namil, performed highly susceptible to rice blast as well as BPH. A mapping population was constructed by using F2 progeny lines derived from cross between Namil(EMS)-bl10,bph1 and Milyang23, a BPH susceptible Tongil type cultivar. DNAs prepared from F2 individuals were used for SSR marker based linkage map skeleton, and F2:3 seeds were subjected to BPH infestation to infer resistance level of corresponding F2 plant. Association analysis between marker genotype and evaluated survival ratio of each progeny line were used to localize the putative chromosomal location(s) involved to BPH resistance. The location was initially located on the subterminal region of the long arm of chromosome 12 flanked by the SSR markers RM1337 and RM277, where at least three BPH resistance genes, Bph1, Bph18, and Bph21, were localized previously.

Toward molecular understanding of flower senescence/abscission, we have identified a mutant, designated as dea1-1D (dealyed abscission1-1D), with delayed flower senescence/abscission syndrome from activation-tagged pools. Phenotypic analysis revealed pleiotropic effects of dea1-1D mutation including delayed flowering as well as smaller serrated leaves. Genetic analysis showed that it is a dominant mutation. Molecular analysis on the flower senescence syndrome indicated that dea1-1D might define novel regulatory branch of flower abscission, controlling expression of ethylene-responsive AP2 transcription factor. On the contrary, triple responses was not affected by dea1-1D mutant. Though the penetrance was not complete, the mutant phenoytpes was shown to be tightly linked with the T-DNA selection marker, BASTA-resistance. We identified the T-DNA insertion site through molecular cloning of the T-DNA flanking genomic DNA and found that a neighboring gene was overexpressed in the dea1-1D mutant. Together with gene expression analysis, we will discuss possible function of DEA1 during flower senescence and abscission.

In plants, the Dof (DNA binding with One Finger) proteins are plant-specific transcription factors with a particular class of zinc-finger DNA-binding domain. The Dof genes have been predicted 30 different Dof genes in the rice Oryza sativa genome by phylogenetic analysis. The mostly Dof proteins contain a conserved region of 50 amino acids with a C2-C2 zinc finger motifs that binds a cis-regulatory element sequence 5’-T/AAAAG-3’. We found that a member of the DOF transcription factor family, Dof1 gene of rice, was expressed to wound from Ds insertion mutant population. Sequencing of the flanking regions of the transposon insertion site indicated that the gene-trap had been inserted near the front of the second exon of OsDof1 gene in chromosome 7. Genomic southern analysis revealed that mutant line contained a single copy of Ds gene trap. The Ds tagged rice mutant line, OsDof1::Ds, wound-inducible GUS expression was identified. To analyze the cis-acting elements, we constructed fusion genes with the OsDof1 promoter fused to the β-glucuronidase (GUS) reporter gene and transformed Arabidopsis and rice plants with these constructs. Wound-induced GUS expression was observed in the leaves of transgenic OsDof1::GUS rice and Arabidospsis plants. These results showed that, OsDof1 protein might be involved in stress responses and growth regulation in plant, might plays a role as a transcription regulator in stress response signal transduction pathways of plant.

Mutagenesis approach in combination with whole genome sequencing has become an import role in genetic and molecular biological study and breeding of crop plants. In this study, we screened the fast neutron M4 10,000 soybean mutant plants based on morphological phenotypes of agronomically important traits and characterized the mutant of interest using resequencing. Fast neutron radiation has been known to be a very effective mutagen to cause large deletion in genome. The screened mutant showed abnormal phenotypes in plant heights, seed sizes, color of leaves, number of leaves, maturity and number of branches etc. Among them, the mutant displaying short plant height and bush type of growth habit was selected for identification of the altered genomic regions. Analysis of deletion sites of genome in interesting soybean mutant was performed using next generation sequencer Illumina Hi-seq. Mutant sequence reads generated by paired-end shotgun library were mapped on a draft soybean reference soybean (G. max cv. Williams 82). The paired-end DNA sequences of 21.6 Gb produced by Illumina Hi-seq produced 21 fold sequence depth. Among the predicted deletion sites, total 3 deletion regions confirmed by PCR. Glyma03g02390 gene and Glyma03g03560 gene were involved in the deletion regions. Glyma03g02390 gene was related to AMP binding, catalytic activity, cofactor binding and metabolic process of cell growth and Glyma03g03560 gene was concerned to oxygen binding, defense response to bacterium, and especially process of indole acetic acid (IAA) biosynthesis. These genes detected in this mutant will be studied about their molecular function in stunted phenotype.

Two sugary mutants, Hwacheong sugary-1 (Hsu1) and Hwacheong sugary-2 (Hsu2) were obtained by chemical mutagenesis from japonica cultivar, Hwacheongbyeo. Sugary mutants exhibited wrinkled and translucent grain with high soluble sugar content. In addition, amber-colored endosperm of sugary mutants was loosely packed due to abnormal starch granules compared to densely packed wild-type. Especially, the grain of Hsu2 mutant was less wrinkled than that of Hsu1, thus Hsu2 can be polished easily. Previous studies reveal that su1 mutant was resulted from mutation in gene for a debranching enzyme, isoamylase but the sequence of the mutated gene has not been identified. To identify the sequence of sugary genes, the map-based cloning strategy was applied. The genetic study revealed that the phenotype of Hsu2 mutant was controlled by two recessive genes. Interestingly, one of the genes was located on chromosome 8 at the position of isoamylase which was known as su-1. This indicates that mutation in isoamylase gene causes sugary endosperm characteristics. However we found different mutation points between the Hsu1 and Hsu2. The point mutation in Hsu1 was occurred at 10th exon whereas the other mutation related with Hsu2 was occurred at 15th exon. As mentioned above, the Hsu2 mutant has less wrinkled shape and less soluble sugar content than the Hsu1 mutant. Thus, we hypothesize that the other gene controlling Hsu2 mutant phenotype may have a role in weakening the effect of the su-1. Further study on the other gene associated with the Hsu2 phenotype is in progress.

In plant, senescence is associated with various aspects of the final stage of leaf development, nutrient relocation from leaves to reproducing seeds and stress resistance, and yield which is the most important trait in crops. Thus, the increase of knowledge on the regulatory processes of plant senescence will allow us to manipulate senescence for agronomic benefit in the future. of genetic studies have been conducted with mutants, where most of studies were focused on the delayed senescence mutants which are associated with positive factors on senescence by treating EMS to Koshikari, we induced a mutant showing early senescence phenotype, which possibly enable us to identify a negative factor of senescence. The appearance of the mutant is identical before booting stage and then the mutant showed senescence phenotype rignt before booting stage whereas Koshikari have health green leaves. The clumn length of the mutant is 98cm and the panicle length is 23cm as same as those of Koshikari. The chlorophyl contents of the mutant leaves, measured by SPAD, decreased during senescence. The soluble protein contents in the mutant leaves also decreased but no differences in the constitution reolved 1D-SDS-PAGE was detected. However, an additional shotgun proteomic approach to detect the differences of the protein constitutions during the senescence in the mutant leaves will be conducted.

Mutant populations generated by ethyl methanesulfonate (EMS) have been used for crop improvement and functional genomics. Since pepper is very recalcitrant to be transformed, EMS mutagenesis can be a very useful to generate useful alleles and to characterize the function of genes. We have been developing a mutant population aiming at 5,000 mutants by treating EMS on seeds of C. annuum ‘Yuwolcho’. A total of 4,300 M1 mutants have been developed until now. Among the 4,300 M1 population, almost 800 M2 mutant lines have been phenotyped and evaluated to confirm the effect of EMS. We categorized seven key organ development and subdivided them into twenty secondary categories. Among them, 50 and 72 families have been shown variations in plant growth and leaf development, respectively. In addition, we detected nucleotide variations using HRM analysis in eIF4E and putative aminotransferase genes. These results demonstrated that our mutant population can be very useful for study function of genes in near future.

Grain size is one of the most important trait determining yield in cereal crops, apart from number of grains per panicle, number of panicles per plant and 1000 seed weight. Other than grain characteristics, plant architecture is another very important factor influencing yield by affecting the amount plant surface area directly exposed to the sun light. Erect panicle is important morphological characteristic which helps in enhancing the yield by allowing sun light to fall directly on leaves unlike curved panicle which blocks sunlight and consequently reduce photosynthesis. A small round grain and erect panicle mutant was obtained by treating Hwacheong rice (japonica) with MNU (N-methyl-N-nitrosourea) chemical mutagen. Through bulked segregant analysis (BSA) using STS (Sequence-Tagged Sites) and SS-STS (Sub-species Specific Sequence-Tagged Site) markers we located the mutated gene on the long arm of chromosome 7 and narrowed down candidate region to 168.75kbp through fine mapping. Mutant manifested characteristics like reduced grain size and plant height, dense and erect panicle and relatively erect plant compared to the wild type. When we crossed the mutant with its parent (Hwacheong), F1 panicle and grain characteristics showed intermediate phenotype, therefore, we concluded that wild type allele of this gene shows incomplete dominance. Scanning electron microscopy(SEM) result shows that increase in width of mutant grain, which changes its shape, is due to increase in width of glume cells. Phenotypic examination shows that dense and erect panicle phenotype is result of reduction in length of rachis, primary and secondary branch.

The early senescence mutant was isolated from the japonica rice Koshihikari through Ethyl-methane-sulfonate(EMS) mutagenesis. The early senescence phenotype was controlled by a single recessive nuclear gene, tentatively symbolized as es-k. Using phenotypic and molecular markers, we mapped the es-k locus to the long arm of chromosome 7 between STS markers 147-1 and 150-1, a physical region of 370-kb. The symptom of early senescence appeared even before heading, while appeared after heading in those of the wild-type rice during senescence. Early stage physiological characteristics of the es-k mutant was similar to that of the wild-type. However, after heading, es-k mutants started to exhibit a significant decrease in chlorophyll content, soluble protein content 10 days earlier compared to normal type. To characterize the interaction with the environment factors, experiments were carried out under controlled temperature and light conditions, respectively. The wild-type leaf color appeared normal irrespective of temperature treatment, while the leaf of es-k mutant appeared pale-green at the low temperature and dark-green at the high temperature. During dark-induced senescence, mutant did not show significant differences compared to normal type. The results show that es-k is sensitive to temperature but not to light.

This study was conducted to determine the physicochemical properties of a giant embryo rice 'P47JB-4-B-5-B' derived from the cross between 'P47', a mutant of 'Hwayoung' induced by T-DNA insertion, and 'Junam'. The grain appearance and chemical components of the embryo were analyzed and compared with a donor cultivar, 'Hwayoung'. The proportion of embryo weight to grain weight of 'P47 JB-4-B-5-B' was 2.2 times heavier (6.7%) than that (3.1%) of 'Hwayoung'. Total free amino acid content (75.81 mg/100 g) of 'P47JB-4-B-5-B' was 2.1 times higher than that of 'Hwayoung'. The GABA content in brown rice was 14.06 mg/100 g in 'P47JB-4-B-5-B' and 6.8 mg/100 g in 'Hwayoung'. Especially, the GABA content in brown rice of 'P47JB-4-B-5-B' remarkably increased (about 33 times from 1.48 mg to 44.81 mg/100 g) 2 days after germination. Continuous frequency distributions and transgressive segregation in embryo length and width were observed in the F2 population of the cross between 'P47' and 'Cheongcheong', indicating that the giant embryo was controlled by quantitative trait loci. However, embryo length and width demonstrated high broad sense heritability, implying that giant embryonic traits could be selected in earlier generations in comparison with other quantitative traits.

A chemical, MNU-induced hulless barley mutant line designated as 'Mutant 98 (M98)' was developed from a Korean hulless waxy barley cultivar, 'Chalssalbori'. The objective of the study was to determine the genetic basis of 'M98' and the possibility of using 'M98' as breeding parent to improve lysine level. Compared to 'Chalssalbori', 'M98' had large embryo and higher lysine content in both the embryo and endosperm. Significantly different lysine content in 'M98' and the other high-lysine barley mutant stocks was observed for two years. However, the genotype by year interaction was not significant. 'M98' was higher than the other high-lysine barley mutant stocks in the percentage of lysine of total amino acid composition (0.75%). The trait of shrunken endosperm of 'M98', which was typical in the high-lysine mutants, was inherited by a single recessive gene. Based on seed morphology and lysine content of F1 seeds, 'M98' had a genetically different gene from the other high-lysine mutants for shrunken endosperm. Segregation of F2 for plump/shrunken endosperm did not fit the expected ratio of Mendelian inheritance except for only one cross combination (GSHO1784 (lys1)/M98). The amino acid analysis of F5 and F6 progenies from the cross between 'M98' and 'Chalssalbori' revealed that the attempt to increase the range of lysine content of plump lines did not go beyond the limit of the average high-lysine barley germplasm.