Green rice leafhopper(GRH), Nephotettix cincticeps Uhier, is one of the major insect pests of rice (Oryza sativa L.) in the temperate growing region of East Asia. GRH sucks sap from both xylem and phoem of susceptible rice varieties, and increased GRH populations cause sooty mold disease on the ears of rice after heading stage. In addition to direct plant destruction, GRH also causes damage to rice plants by transmitting rice dwarf viruses causing rice dwarf viruses disease which could decrease the yield of rice. Development of GRH resistant rice varieties for reducing yield loss is an important objective in current breeding programs. In this study, we developed three SSR markers(RM18166, RM516, RM18171) and one Indel marker(Indel15040) which could select Grh1-resistant varieties using population derived from cross lines between Grh1-resistant variety ‘Singwang’ which contains Grh1 gene and susceptible variety ‘Ilpum’. PCR products of RM18166 which was one of the developed markers were easily detected in agarose gel. These markers will be useful for development of the Grh1-resistant varieties through marker-assisted selection(MAS) without bio-examination in rice breeding

Transgenic potatoes expressing glyceraldehyde-3-phosphate dehydrogenase (GPD), isolated from the oyster mushroom, Pleurotus sajor-caju, had increased tolerance to salt stress (Jeong et al. 2001). To examine the physiological mechanisms enhancing salt tolerance in GPD transgenic rice plants, the salt tolerance of five GPD transgenic rice lines (T1–T5) derived from Dongjin rice cultivar was tested in a fixed 150-mM saline environment in comparison to two known wild-type rice cultivars, Dongjin (salt sensitive) and Pokali (salt tolerant). Transgenic lines T2, T3, and T5 showed a substantial increase in biomass and relative water content compared to Dongjin. Stomatal conductance and osmotic potential were higher in the GPD transgenic lines and were similar to those in Pokali. The results are discussed based on the comparative physiological response of GPD transgenic lines with those of the salt-sensitive and salt-tolerant rice cultivars.

Bakanae disease is one of the most serious and oldest problems of rice production, which was first described in 1828 in Japan (Ito and Kimura 1931). This disease may infect rice plants from the pre-emergence stage to the mature stage, with severe infection of rice seeds resulting poor germination or withering (Iqbal et al. 2011). Under favorable environmental conditions, infected plants have the capacity to produce numerous conidia that subsequently infect proximate healthy plants, resulting in major yield loss (Ou 1985). One hundred sixty nine NILs, YR28297 (BC6F4) generated by five backcrosses of Shingwang with the genetic background of susceptible japonica variety, Ilpum were used for QTL analysis. Rice bakanae disease pathogen, CF283, was mainly used in this study and inoculation and evaluation of bakanae disease was performed with the method of the large-scale screening method developed by Kim et al. (2014). A major QTL for resistance against bakanae disease on chromosome 1 was identified using SSR marker, RM9, which explaining 65 % of the total phenotype variation. The major QTL designated as qBK1 and mapped to a 4.4 Mbp region between RM24 (19.30 Mb) and RM11295 (23.72 Mb). The results of this study are expected to provide useful information toward developing resistant rice lines to this detrimental fungal disease.

A sugary mutant with low total starch and high sugar content was compared with its wild type Sindongjin for grain-filling caryopses. In the present study, developing seeds of Sindongjin and sugary mutant from the 11th day after flowering (DAF) were subjected to RNA sequencing (RNA-Seq). A total of 30,385 and 32,243 genes were identified in Sindongjin and sugary mutant. Transcriptomic changes analysis showed that 7,713 differentially expressed genes (DEGs) (log2 Fold change ≥1, false discovery rate (FDR) ≤ 0.001) were identified based on our RNA-Seq data, with 7,239 genes up-regulated and 474 down-regulated in the sugary mutant. A large number of DEGs were found related to metabolic, biosynthesis of secondary metabolites, plant-pathogen interaction, plant hormone signal transduction and starch/sugar metabolism. Detailed pathway dissection and quantitative real time PCR (qRT-PCR) demonstrated that most genes involved in sucrose to starch synthesis are up-regulated, whereas the expression of the ADP-glucose pyrophosphorylase small subunit (OsAGPS2b) catalyzing the first committed step of starch biosynthesis was specifically inhibited during the grain-filling stage in sugary mutant. Further analysis suggested that the OsAGPS2b is a considerable candidate gene responsible for phenotype of sugary mutant.

Bakanae disease incidence threat is an increasing trend in the top rice growing countries. Despite it is essential to identify the resistant genes and underlying mechanisms of bakanae disease to develop resistant varieties, there are very limited genetic studies on bakanae disease in rice. The indica rice variety Shingwang was selected as resistant donor to bakanae disease. One hundred sixty nine NILs, YR28297 (BC6F4) generated by five backcrosses of Shingwang with the genetic background of susceptible japonica variety, Ilpum were used for QTL analysis. Rice bakanae disease pathogen, CF283, was mainly used in this study and inoculation and evaluation of bakanae disease was performed with the method of the large-scale screening method developed by Kim et al. (2014). The proportion of healthy plants of Shingwang and Ilpum after inoculation was confirmed using bakanae disease pathogen, CF283. While inoculated Ilpum showed thin and yellowish-green phenotype which is typical symptom of Bakanae disease, Shingwang showed similar healthy phenotype with control plants. A major QTL for resistance against bakanae disease on chromosome 1 was identified using SSR marker, RM9, which explaining 65 % of the total phenotype variation. The major QTL designated as qBK1 and mapped to a 4.4 Mbp region between RM24 (19.30 Mb) and RM11295 (23.72 Mb). The information of qBK1 could be useful for improving rice bakanae disease resistance in marker-assisted breeding.

Plant specific gene family, NAC (NAM, ATAF, and CUC) transcription factors have been characterized for their roles in plant growth, development, and stress tolerance. In this study, we isolated OsNAC58 gene from rice and analysed expression level by inoculation of bacterial leaf blight pathogen, Xanthomonas oryzae pv. oryzae (Xoo). NAC transcription factor family can be divided into five groups (I–V). On the basis of phylogenetic analysis, OsNAC58 was fall into group III. 35S::OsNAC58-GFP fusion protein was localized on the nuclei. To investigate its biological function in the rice, we constructed vector for overexpression in rice, and then generated transgenic rices. Gene expression of OsNAC58-overexpressed transgenic rice lines were analyzed by northern blot. Analysis of disease resistance to pathogen Xoo, twelve OsNAC58-overexpressed transgenic rice lines showing high expression level of OsNAC58 were shown more resistant than wild type. These results suggest that OsNAC58 gene may play regulatory role during pathogen infection.

Understanding salt tolerance mechanisms is important for the increase of crop yields, and so, several screening approaches were developed to identify plant genes which are involved in salt tolerance of plants. Here, we transformed the Arabidopsis cDNA library into a salt-sensitive calcineurin (CaN)-deficient (cnbD) yeast mutant and isolated the colonies which can suppress salt-sensitive phenotype of cnbD mutant. Through this functional complementation screen, a total of 34 colonies functionally suppressed the salt-sensitive phenotype of cnbD yeast cells, and sequencing analysis revealed that these are 9 genes, including CaS, AtSUMO1 and AtHB-12. Among these genes, the ectopic expression of CaS gene increased salt tolerance in yeast, and CaS transcript was up-regulated under high salinity conditions. CaS-antisense transgenic plants showed reduced root elongation under 100 mM NaCl treatment compared to the wild type plant, which survived under 150 mM NaCl treatment, whereas CaS-antisense transgenic plant leaves turned yellow under 150 mM NaCl treatment. These results indicate that the expression of CaS gene is important for stress tolerance in yeast and plants.

Development of transgenic plant increasing crop yield or disease resistance is good way to solve the world food shortage. However, the persistence of marker genes in crops leads to serious public concerns about the safety of transgenic crops. In the present study, we developed marker-free transgenic rice inserted high molecular-weight glutenin subunit (HMW-GS) gene (Dx5) from the Korean wheat cultivar ‘Jokyeong’ using Agrobacterium-mediated co-transformation method. The Dx5’s own promoter was used for protein expression. Two expression cassettes comprised of separate DNA fragments containing only the Dx5 and hygromycin resistance (HPTII) genes were introduced separately into Agrobacterium tumefaciens EHA105 strain for co-infection. Each EHA105 strain harboring Dx5 or HPTII was infected into rice calli at a 3: 1 ratio of EHA105 with Dx5 gene and EHA105 with HPTII gene expressing cassette. Then, among 270 hygromycin-resistant transformants, we obtained 27 transgenic lines inserted with both the Dx5 and HPTII genes into the rice genome. We reconfirmed integration of the Dx5 gene into the rice genome by Southern blot analysis. Wheat Dx5 transcripts in T1 rice seeds were examined with semi-quantitative RT-PCR. Protein expression of the Dx5 was analyzed with Western blot using polyclonal antibody recognising x-type of glutenin subunits in T1 seeds. It was suggested that the protein-processing system was conserved between rice and wheat. Finally, the marker-free plants containing only the Dx5 gene were successfully screened at the T1 generation.

Bakanae disease of rice, caused by Fusarium moniliforme Sheldon, the imperfect stage of Gibberella fujikuroi, is one of the most important rice diseases worldwide, but no rice variety has been found to be completely resistant to this fungus. Cultivation of resistant cultivars is the most beneficial way of reducing quantitative or qualitative losses to for bakanae disease in rice. To facilitate the study of this disease, accurate and large scale screening methods were developed for the inoculation and evaluation of Bakanae disease. Even and large scale infection was achieved by using F. moniliforme spore in tissue embedding cassette and seedling tray. The efficiency of F. moniliforme infection with the concentration of 1×106 spore/ml caused better distribution (F-value=33.96) than 1×102 (F-value=10.69), and 1×104 spore/ml (F-value=2.63). We established new criteria of healthy and non-healthy plant, and introduced calculation of proportion of healthy plants to meet fast evaluation of resistance level of each variety. The effect of F. moniliforme strains containing different genetic background was also evaluated with rice varieties to figure out the stability of resistance level. GA3 response of rice variety was significantly correlated with bakanae disease, but it did not adequate for direct indicator of bakanae disease resistance. These results indicated that a large scale infection method developed in this study is fast and reproducible, as well as a disease evaluation system provides an accurate measurement of bakanae disease resistance of rice.

Farmers have use phosphate fertilizer to provide sufficient yields. However, overuse of phosphorus accumulate in soil and causes soil and water pollution. We evaluated the phosphate acquisition and growth characteristics of OsPT1 transgenic rice (OsPT1-OX, over-expressing the high affinity phosphate transporter 1) in high phosphate soils with different level of nitrogen fertilizer treatment to investigate removing ability of excessive phosphate from soil. OsPT1-OX had shorter culm length but more tillers than those of wild-type plants in each soil conditions. Phosphate content per dry weight of OsPT1-OX was 1.8 times higher than that of wild-type under control fertilizer treated conditions. Although the dry weight of OsPT1-OX was not different from that of wild-type plants, whole plant phosphate content was 1.7 times higher than that of wild-type plants under control fertilizer conditions. Tiller number and phosphate content per dry weight of wild-type plants increased following high levels of phosphate application but did not change by following additional nitrogen application. Tiller number and phosphate content per dry weight of OsPT1-OX did not change under the high phosphate condition, but increased following nitrogen application under similar conditions. Whole plant phosphate content was highest under high nitrogen and high phosphate application conditions. These results suggest that OsPT1-OX may reduce phosphate content in soils containing excess phosphate and may be further effective under high nitrogen condition.

Plant specific gene family, NAC (NAM, ATAF, and CUC) transcription factors have been characterized for their roles in plant growth, development, and stress tolerance. In this study, we isolated OsNAC69 gene and analysed expression level by inoculation of bacterial leaf blight pathogen, Xanthomonas oryzae pv. oryzae (Xoo). NAC transcription factor family can be divided into five groups (I–V). On the basis of phylogenetic analysis, OsNAC69 was fall into group II. OsNAC69 was strongly induced 1 hr after infected with Xoo. To investigate its biological function in the rice, we constructed vector for overexpression in rice, and then generated transgenic rices. Gene expression of OsNAC69-overexpressed transgenic rice lines were analyzed by northern blot. Analysis of disease resistance to pathogen Xoo, nine OsNAC69-overexpressed transgenic rice lines showing high expression level of OsNAC69 were shown more resistant than wild type. These results suggest that OsNAC69 gene may play regulatory role during pathogen infection.

Rice stripe disease, caused by rice stripe virus (RSV), is one of the major virus diseases in east Asia. The objective of this study was conducted to identify new resistance genetic source to rice stripe virus (RSV) disease. Genetic diversity of 155 rice cultivars was evaluated using 9 co-dominant InDel markers and STS marker ST10. These cultivars were classified into two groups by cluster analysis based on Nei`s genetic distances. The marker showed different band pattern among RSV resistance or susceptible cultivar. In comparison with bioassay for RSV resistance and genotyping using SSR markers showed that Stv-bi and InDel 7 marker observed recombination value within 3.8% and RSV resistance gene was closely related to InDel 7. Also InDel 7 divided as resistance type alleles and susceptible type alleles except for some varieties. Interestingly, 02428, Daw dam, Erguailai, Padi Adongdumarat, PERVOMAJSZKIJ, and Tung Ting Wan Hien 1 showed Japonica type in InDel 7 marker. However, these cultivars revealed resistant to RSV bioassay. These results indicate that those cultivar can be able to get the different gene resistance with Stv-bi gene. Newly identified resistance gene is considered useful for improving RSV resistance in japonica rice. Therefore, we will progress the allelism test and genetic analysis for identification of new gene source.

Glycolysis is responsible for the conversion of glucose into pyruvate and for supplying reducing power and several metabolites. Fructose-1,6-bisphosphate aldolase (AtFBA1), a central enzyme in the glycolysis pathway, was isolated by functional complementation of the salt-sensitive phenotype of a calcineurin (CaN)-deficient yeast mutant. Under high salinity conditions, aldolase activity and the concentration of NADH were compromised. However, expression of AtFBA1 maintained aldolase activity and the NADH level in yeast cells. AtFBA1 shares a high degree of sequence identity with known class I type aldolases, and its expression was negatively regulated by stress conditions including NaCl. The fusion protein GFP-AtFBA1 was localized in the cytosol of Arabidopsis protoplasts. The seed germination and root elongation of AtFBA1 knock-out plants exhibited sensitivity to ABA and salt stress. These results indicate that AtFBA1 expression and aldolase activity is important for stress tolerance in yeast and plants.

In order to improve rice dough functionality, we cloned 4 kinds of high-molecular-weight glutenin subunit (HMW-GS) genes from bread wheat, ‘Jokyeong’. Among them, we first examined Dx5 gene to generate marker-free transgenic rice for advanced quality processing of bread and noodles. The GluB1 promoter was inserted into binary vector for seed specific expression of the Dx5 gene. Two expression cassettes comprised of separate DNA fragments containing only the high-molecular-weight glutein subunit (HMW-GS) protein (Dx5) and hygromycin phosphotransferase II (HPTII) resistance genes were introduced separately to tumefaciens EHA105 strain for co-infection. Each EHA105 strain harboring Dx5 or HPTII was infected to rice calli at 3: 1 ratio of Dx5 and HPTII, respectively. Then among 66 hygromycin-resistant transformants, we obtained two transgenic lines inserted both with Dx5 and HPTII gene to rice genome. We reconfirmed integration of the Dx5 and HPTII genes into the rice genome by Southern blot analysis. Wheat Dx5 transcriptsin rice seeds was examined with semi-quantitative RT-PCR. Finally, the marker-free plants containing only Dx5 gene were successfully screened at T1 generation. This result also provides that co-infection system with two expression cassettes could be efficient strategy to generate marker-free transgenic rice plants.

With both common and Tartary buckwheat species, this study was aimed at producing new commercially useful bio-materials with higher nutritional and medicinal value due to higher components for health promotion and diseases care. In common buckwheat sprouts, it was found that root length at 20℃ was longer (5.93 cm) than at 25 and 30℃, whereas the hypocotyls length, fresh weight of each sprout, and whole fresh weight showed the highest value at 30℃. For Tartary buckwheat, the root length, hypocotyl length and fresh weight of each sprout and whole fresh weight were also the highest at 30℃. Common buckwheat (Suwon No.1) and Tartary buckwheat (KW45) sprouts cultured at 20℃ showed that hypocotyl length, fresh weight of each sprout, and whole fresh weight in the control were higher than those sprouts treated with 5% and 10% deep sea water (DSW), while the sprouts cultured at 30℃ showed were significantly longer hypocotyls than the control or 5% DSW treatment.