• Proceedings of the Korean Society of Life Science Conference
• /
• 2007.10a
• /
• pp.45.2-45.2
• /
• 2007

See Full Text

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2021.10a
• /
• pp.25-25
• /
• 2021

• Proceedings of the Korean Society of Plant Pathology Conference
• /
• 2004.10a
• /
• pp.48-52
• /
• 2004

We have found the role of rice mitogen-activated protein kinase kinase kinase (MAPKKK), OsEDR1, as controling hypersensitive response (HR) and increased disease resistance to rice blast fungus Magnaporthe grisea. Generation of transgenic rice plants through introduction of the over-expression construct of OsEDR1 using Agrobacterium-mediated transformation results in lesion mimic phenotype. Up-regulation of defense mechanism was detected through detection of increased transcription level of rice PBZ1 and PR1a. Inoculation of rice blast fungus on the lesion mimic transgenic lines displayed significantly increased resistance. The disease symptoms were arrested like HR responses which are commonly detected in the incompatible interactions. High accumulation of phenolic compounds around developing lesions was detected under UV light. There was variation among transgenic lines on the timing of lesion progression as well as the lesion numbers on the rice leaves. Transgenic lines with few lesions also show increased resistance as well as equal amount of grain yields compared to that of wild type rice cultivar Nipponbare. This is the first report of the MAPKKK as a positive regulator molecule on defense mechanism through inducing HR-like cell death lesion mimic phenotype. The application of OsEDR1 is highly expected for the development of resistant cultivars against rice pathogens.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.13-13
• /
• 2017

By the progress of genome sequencing, infrastructures for marker-assisted breeding (MAB) of rice came to be established. Fine mapping and gene isolation have been conducted using the breeding materials derived from natural variations and artificial mutants. Such genetic analysis by the genome-wide dense markers provided us the knowledge about the many genes controlling important traits. We identified several genes or quantitative trait loci (QTL) for heading date, blast resistance, eating quality, high-temperature stress tolerance, and so on. NILs of each gene controlling heading date contribute to elongate the rice harvest period. Determination of precise gene location of blast resistance gene pi21, allowed us to overcome linkage drag, co-introduction of undesirable eating quality. We could also breed the first practical rice cultivar in Japan with a brown planthopper resistance gene bph11 in the genetic back-ground of an elite cultivar. Discovery of major and minor QTLs for good eating quality allowed us to fine-tune of eating quality according to the rice planting area or usage of rice grain. Many rice cultivars have bred efficiently by MAB for several traits, or by marker-assisted backcross breeding through chromosome segment substitution lines (CSSLs) using genetically diverse accessions. We are also systematically supporting the crop breeding of other sectors by MAB or by providing resources such as CSSLs. It is possible to pyramid many genes for important traits by using MAB, but is still difficult to improve the yielding ability. We are performing a Genomic Selection (GS) for improvement of rice biomass and grain yield. We are also trying to apply the genome editing technology for high yield rice breeding.

• Korean Journal of Food Science and Technology
• /
• v.49 no.1
• /
• pp.1-7
• /
• 2017

Molecular structure, physicochemical properties, and in vitro digestibility of starch from Korean rice cultivars for special uses (Baegjinju 1, Hanareum, Deuraechan, and Goami 4) were investigated. The starch from Baegjinju 1 had the lowest amylose content (9.7%) and Hanareum, Deuraechan, and Goami 4 had intermediate amylose (20-25%) contents. Baegjinju 1 had a lower proportion of short amylopectin branch chains than the other rice starches. Hanareum had the lowest relative crystallinity and the highest intensity ratio of $1047cm^{-1}/1022cm^{-1}$ among the rice starches. The starch from Goami 4 had a higher pasting temperature and lower gelatinization enthalpy than the other rice starches. Peak viscosity of rice starch from Baegjinju 1 was substantially higher than peak viscosity of other rice starches. Rice starch from Baegjinju 1 had significantly higher rapidly digestible starch content and lower resistant starch content than other rice starches, whereas there was no significant difference in resistant starch content among the rice starches.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.329-329
• /
• 2017

The study was conducted to investigate the effects of different harvesting time on pasting properties of starch in three colored rices. Seven major parameters of starch pasting properties, peak viscosity (PKV), hot pasting viscosity (HPV), cool pasting viscosity (CPV), setback (CPV minus PKV), breakdown (PKV minus HPV), peak time, and pasting time were determined by Rapid Visco Analyzer. The peak viscosity, hot viscosity, cool viscosity and peak time were influenced by different harvesting times. Pasting time was delayed slightly with prolonged harvesting time in all rice cultivars. Pasting temperature in each rice cultivar differed from each harvesting time, and pasting temperature of the two rice cultivars, Hongjinju and Joseongheugchal, showed the highest at the 40 days after heading and then it decreased at the final harvesting time. With the delay of the harvesting time, peak viscosity, hot viscosity, cool viscosity, setback value and pasting temperature did not exhibit a regular trend depending on their genetic characteristics. Branch chain length distribution of amylopectin was demonstrated a distinct difference among these colored rices. In changes of amylopectin branch chain-length distribution, the amylopectin structure of Hongjinju rice cultivar as affected by different harvesting time, the shortest chain length of amylopectin in rice starch harvested at 20 days after heading was characterized by the significant increase in A chains with $DP{\geq}12$ and remarked decrease in long chains $37{\leq}DP$ compared to that of 30, 40, and 50 days after heading. In particular, when harvesting time is delayed the distribution percentage of short chain (A chains with $DP{\geq}12$) was increased except for the rice which harvested 20 days after heading. The similar results were also observed in Sintoheugmi rice cultivar like that of Hongjinju rice cultivar. Otherwise, distribution percentage of the shortest chain length of amylopectin in rice starch harvested at 20 days after heading was characterized by the significant decrease in A chains with $DP{\geq}12$ and remarked increase in B chains $13{\leq}DP{\geq}24$ compared to that of 30, 40, and 50 days after heading.

• Korean Journal of Agricultural Science
• /
• v.41 no.4
• /
• pp.327-334
• /
• 2014

Light intensity is one of the most important requirements for plant growth, affecting growth, development, survival, and crop productivity. Sunlight is the main energy source on Earth which is energy used by photosynthesis to convert light energy to chemical energy. In this study, the light use efficiency and photosynthetic characteristics of high-quality rice cultivars were evaluated after shading on ripening stage. For the study, we treated of three levels of shade (0, 50 and 70%) on rice at ripening stage and two levels of nitrogen (9 and 18 kg/10a) used three high yielding rice cultivars, such as Boramchan, Hopum, and Honong. The shade was given for the respective plots from heading up to harvesting. We were performed to determine growth survey, SPAD and chlorophyll fluorescence every 10 days interval after shading on ripening stage. At harvest stage, grain yield and yield components were determined. Results of analysis of the results representing the maximum photosynthetic efficiency of PSII, Fv/Fm, and SPAD were decreased by depending on the time at full sunlight. But shade treatments were not changed and a significant difference among cultivars did not appear. Compared with the full sunlight, shade treatments significantly delayed ripening rate and decreased rice quality of cultivated rice. Therefore, rice yield, can be reduced in proportion to the shading density is apparent, the rate of decrease was not observed difference between varieties, when protected from light 70%, and decreased to less than 50%. The adverse effects of low light intensity on the yield and yield components were not able to significantly minimize by the nitrogen level.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.48 no.6
• /
• pp.479-483
• /
• 2003

Knowledge of N accumulation during the vegetative growth stage of rice (Oryza sativa L.) is useful for determining the need for topdressing fertilizer N at panicle initiation and booting stage. The chlorophyll content showing SPAD threshold values generated by a simple and portable diagnostic instrument, chlorophyll meter, enables implement the measures of greenness and/or relative chlorophyll contents of leaves. Two-year field experiment was conducted to evaluate the possible application of the chlorophyll meter for N diagnosis in transplanted paddy rice. The chlorophyll meter threshold values (SPAD reading) were taken from uppermost fully expanded leaves at 10days interval from 10 days after transplanting. SPAD readings and N contents of rice leaf blade were closely related at the maximum tillering stage. SPAD readings during growth period showed M-shaped distribution, sharply finished to drop at 20 days after heading date. As N fertilizer increased, the SPAD readings increased. The SPAD readings showed more critical and clear difference in immature paddy field than in ordinary paddy field, where the former soil showed higher response to N fertilizer topdressed. Based on the PAD readings for obtaining an optimum sink size bearing the maximum grain yield, N fertilizer to be dressed at the panicle initiation stage is to be adjusted within the SPA$\times$tillers value range 888 in ordinary paddy, and 800 in immature paddy vice. Among the cultivars tested, Huckhyangbyeo, Jinpumbyeo, Ansungbyeo, Sobibyeo, Manpungbyeo, Sangmibyeo, Jinbongbyeo, showed high SPAD values, whereas the cultivars, Nonghobyeo, Saechuchungbyeo, Hwabongbyeo, Mananbyeo, did low values and others intermediate SPAD threshhold values.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.31 no.1
• /
• pp.43-48
• /
• 1986

The experiment was conducted to know the varietal difference in changing aspect of daily filling sink during of rice using three cultivars; ‘Suweon 295’ (japonica), ‘Suwoen 264’ and ‘IR 1317-70-1’ (semi-dwarf indica) cultivated in the field and green house of the Crop Experiment Station in 1983. There was not significant varietal difference in flowering habit and duration of flowering period each panicle. Semi-dwarf indica cultivars showed shorter days to physiological maturity of rice kernel than the japonica one. The former also displayed earlier decrease in water content of rice grain during ripening than the latter. Japonica variety revealed larger difference in ripening advancement between vigorous florets and inferior one than semi-dwarf indica varieties. The semi-dwarf indica rice cultivars expressed significantly shrewder parabola of daily filling of sink per panicle during ripening than the japonica one. The time showing maximum capacity of daily filling of sink per panicle during ripening was 10-12 days after anthesis. The filling capacity of daily sink filling per panicle for 'IR 1317-70-1', 'Suweon 264' and 'Suweon 265' at this time were about 240 mg, 165 mg and 145 mg, respectively. Pattern of sink filling per panicle during ripening was slightly changed by the cultural environment. ‘Suweon 295’ showed slightly sharper parabola and 2-3 days earlier time showing maximum capcity of daily sink demand per panicle during ripening in the field than those in the green house.

• Research in Plant Disease
• /
• v.7 no.2
• /
• pp.86-92
• /
• 2001

This experiment was carried out to analyze the recent epidemic of rice blast in southern provinces of Korea in 1999 and 2000. Incidences of leaf blast and panicle blast in these years were 1.5 and 2.9 times greater than those in 1998, respectively. Cultivation areas of rice cultivars, Daesan, Ilmi and Dongan bred from Milyang 95 as a recurrent parent increased over the country from 11% in 1998 to 38.4% in 2000, which were grown in more than 85% of total paddy fields in Jeonnam province. Predominant race populations of Pyricularia grisea in the farmers' fields had been changed from KJ-301 to KI-1117 in 1999 and KI-1113 and KJ-105 in 2000. Distribution ratio of the KI-1117 race in 1998 in the southern provinces was 1.7%, but increased to 30% in 1999. Although the cultivars Daesan, Ilmi and Dongan have shown wide spectrum of resistance to many races including KJ-301, they were susceptible to such races as KI-1117, KI-1113 and, KJ-105. These three races could be further classified into two sub-races, KI-1117 and KI-1117a, KI-1113 and Kl-1113a, and KJ-105 and KJ-105a based on virulence to Daesan. The newly classfied races, Kl-1113a, Kl-1117a, and KJ-l05a were also pathogenic to Ilmi and Dongan. This indicates that rice blast epidemic in southern provinces in 1999 and 2000 resulted from the breakdown of the resistance of Daesan, Ilmi and Dongan by the rapid increase of virulent races KI-1117, KI-1113, KJ-105 and their new sub-races.