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.

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.

The rice sucrose synthase 3 (RSUS3) localized predominantly inrice seed endosperm may play an important role in the starch filling in the milky stage of rice seed. As the genetic diversity at this locus is not known yet, forty three rice varieties/accessions were objected to amplify full sequence of the RSUS3 to examine the distribution of DNA polymorphisms. A total of 254 sequence variants, including 82, 150 and 22SNP sand indels, were successfully identified in whole length of 7,733bp sequence comprising promoter, exon and intron, and 3’ down stream non transcribed region(NTR). Eleven haplotypes were distinguishable among 43 rice varieties based on the nucleotide variation on the three defined regions (5’NTR, transcript and 3’NTR). The promoter region showed the occurrence of a base change on a cis-element which might involve a functional role of the motif in seed-specific expression. Non random process seemed to be acted in the genetic diversity of RSUS3geneamongricegermplasmusedinthisstudy. The analysis of polymorphism sites indicated a history of eleven minimum recombination mostly occurred in the transcribed region. This result might provide an insight for a clasditic approach for establishing future genetic association studies of RSUS3locus.

Field resistance is defined as the resistance that allows effective control of a parasite under natural field condition and is durable when exposed to new races of that parasite. To identify the genes for field resistance against rice blast, quantitative trait loci (QTLs) conferring field resistance in japonica rice cultivars were detected and mapped using SSR markers. QTL analysis was carried out in 190 RILs population from the cross between Suweon365 (moderately resistance) and Chucheong (highly susceptible). Fourteen QTLs for nine blast races inoculated were detected on chromosomes 1, 2, 4, 5, 6, 7, 11 and 12. They explained from 6.4 to 39.7% of total phenotypic variation. Eight QTLs for blast nursery screening in 4 regions for three years were detected on chromosomes 1, 2, 4, 5, 11 and 12. The phenotypic variation was explained by each QTL ranged from 5.9 to 38.0%. Three BC2F5 backcrossed progeny lines were developed to transfer the QTLs into the susceptible cultivar Chucheong as a recurrent parent. A NIL4 containing two QTLs Qbl6.2 and Qbl7 for blast races showed the reaction 6 to 7 in blast nursery in 2007 and 2008, respectively. Two lines NIL143 and NIL93 containing Qbl11.2 and Qbl12.1 for QTLs related with field resistance, respectively, were 3 to 4 reactions in blast nursery.

Sucrose synthase 3 which is a third active gene present in rice, is localized predominantly in rice endosperm. This sucrose synthase 3 may play an important role in the starch filling in the milky stage rice seed, probably involving in the starch physicochemical properties. As the genetic diversity at this locus is little informed, forty three rice consisting of japonica, indica and Oryza rufipogon were targeted to amplify full sequence of sucrose synthase 3 to examine the frequency and distribution of nucleotide polymorphism. Total of 755 all sequence variants detected, 491 single nucleotide polymorphisms (SNPs) and 264 indels were successfully identified in 7618 bp of sequence containing the sucrose synthase 3 transcript, promoter and 3' non-transcribed region. The frequency of nucleotide changes and indels were high, on average one polymorphism per 15.5 bp and one indel per 28.9 bp with 11 sequence-based haplotypes distinguishable among the varieties and lines. Both the frequency of nucleotide changes and indels were frequent in non-coding region, but rare in coding region. Sequencing a polymorphism region in the promoter showed one base change on one of cis-element from T (CATGCATA to A (CATGCACA) that might implicate in seed specificity. The presence of a high number of haplotype shared by a few varieties indicated a little information on linkage disequilibrium.

The giant embryo(ge) mutation was genetically mapped to chromosome 7 by Koh et al. The ge mutations were analyzed at the morphologic and genetic level by Hong et al. And this publication linked the GE gene as being required for proper endosperm development. Researchers in Dupont cloned the GE gene, sequenced and characterized the ge alleles of the mutants. the three giant embryo mutant lines we obtained by treating MNU to Hwacheongbyeo, a japonica type Korean rice cultivar, differed in their embryo and endosperm size and their embryo/endosperm ratios. We named these alleles affecting the embryo size in rice GE, ge-m, ge, ge-s (GE: the wild type, ge-m: embryo slightly larger than in the wild type, ge: large embryo, ge-s: embryo even larger than in ge). The ORFs and introns of the four different alleles in the GE locus were sequenced and compared with the corresponding sequences in the patent that dupont presented. Each mutant alleles sequence showed a few SNPs in the ORF region. Two SNPs were shared among the three mutant lines and each mutant line hab one or two additional SNPs. Further studies are in progress regarding the GE RNA expression level in each mutant line and the F1 seed phenotypes and allelism relationship among the mutant lines.

Plant proteomic study requires a high-throughput separation to the detection and analysis of peptides and proteins by mass spectrometry (MS) to detect low abundant proteins. Together, efficient separation and MS can lead to the detection of thousands of plant proteins in a cell or tissue and help build proteome maps that can provide a global snap-shot of the cell or tissue status. Recently efficient separations based on the HPLC were introduced to allow deeper protein detection and improve throughput. For the HPLC based methods, Multidimensional Protein Identification Technology (MudPIT) and 1D-Gel-LC-MS/MS will be introduced. In MudPIT analysis, all proteins in a sample are digested into peptides before the separation step then the mixture of peptides are separated through the biphasic capillary column and sequentially eluted into the mass spectrometer and analyzed. 1D-Gel-LC-MS/MS separates protein samples in 1D-SDS-Gel then the proteins in each band were ingel-digested into peptides followed by peptides separation with Reverse Phase column and elution into the mass spectrometer. The main goal of this presentation is to introduce the recent protein separation and identification methods based on the HPLC coupled with MS analysis including conventional method of 2D-PAGE.

This study was carried out to obtain the basic information for breeding cold-tolerant rice varieties with high yield-productivity through wide crosses between indica and japonica rice. Genetic analysis was conducted using 55 F1 s obtained from half-diallel crosses among eleven cultivars of various origin including indica and japonica rice. Screening for cold tolerance was done with cold-water irrigation after transplanting until ripening stage. Both general combining ability (GCA) and specific combining ability (SCA) effects were highly significant in all characters associated with dry matter accumulation at 30 and 50days after cold-water irrigation (DAC). The variance of GCA was much larger than that of SCA in plant height, shoot dry weight per plant (DWP), crop growth rate (CGR) and cold-water response index (CRI) of these characters except CRI of shoot dry weight per plant. The DWP, CGR and CRI of these characters of Gaochan 102, Tong88-7 and TR22183 were markedly higher than those of the others. GCA effects of these varieties on DWP, CGR and their CRI were also higher than those of the others, indicating that they are useful as promising parents for breeding cold-tolerant varieties. Analysis of genetic parameters for 11~times 11 half-diallel F1 s revealed that inter-locus gene interaction were concerned in the expression of plant height at 50 DAC, CRI of DWP at 50 DAC, and CRI of CGR, and that intra-locus gene interaction for plant height and the other characters were partial dominance and over-dominance, respectively. Narrow-sense heritability (h2 N ) was the highest in plant height as 0.729, and the lowest in CRI of DWP at 30 DAC as 0.048, suggesting that selection for cold tolerance will be quite effective in case that the selection criterion is the performance itself.f.