• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.66.2-66
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• 2003

A gain-of-function mutant, SHM-11 obtained through gamma-ray mutagenesis, is resistant to rice blast caused by Magnaporthe grisea while wild type Sanghaehyanghyella is highly susceptible to the same disease. The resistance in the mutant was not race-specific when we tested with four races (KJ-201, KI-1113a, KI-313, KI-409) of M. grisea. To identify genes involved disease resistance in the gain-of-function mutant, genes specifically expressed in the mutant were selected by suppression subtractive hybridization using cDNAS of blast-inoculated mutant and wild type as a tester and a driver, respectively, Random 200 clones from the subtracted library were selected and analyzed by DNA sequencing. The sequenced genes represented three major groups related with disease resistance； genes encoding PR proteins, genes probably for phytoalexin biosynthesis, and genes involved in disease resistance signal transduction. A gene encoding a putative receptor-like protein kinase was identified as highly expressed only in the gain-of-function mutant after blast infection. The role of the putative receptor-like protein kinase gene during blast resistance will be further studied.

• 한국식품과학회지
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• 제32권1호
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• pp.75-81
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• 2000

아밀로오스함량, 당함량, 전분입자의 형태 등에 차이를 보이는 8품종 변이체 벼들의 쌀빵가공성에 대한 제분방법(습식 및 건식)의 차이에 대해서 검토하였다. 이들 8품종의 최대수분흡수량은 품종에 따라 상당히 차이가 있어 shr.은 61.5%, 분질미는 48.4%였고, 화청벼 남풍벼 및 그들의 변이체들은 아밀로오스 함량이 낮은 품종의 쌀일수록 최대 수분흡수량은 증가하고 있었다. 건식제분에 의해서 제조한 쌀빵이 성형성, 기계적인 물성(경도, 탄력성, 응집성. 씹힘성) 및 관능검사에 의한 질감의 면에서 습식제분의 경우보다 우수하였다.

• Plant Biotechnology Reports
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• 제4권4호
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• pp.281-291
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• 2010

The rice CHLH gene encodes the $Mg^{2+}$-chelatase H subunit, which is involved in chlorophyll biosynthesis. Growth of the chlorophyll-deficient oschlh mutant is supported by mitochondrial activity. In this study, we investigated the activity of mitochondrial respiration in the illuminated leaves during oschlh seedling development. Growth of mutant plants was enhanced in the presence of 3% sucrose, which may be used by mitochondria to meet cellular energy requirements. ATP content in these mutants was, however, significantly lowered in light conditions. Low cytosolic levels of NADH in illuminated oschlh mutant leaves further indicated the inhibition of mitochondrial metabolism. This down-regulation was particularly evident for oxidative stressresponsive genes in the mutant under light conditions. Hydrogen peroxide levels were higher in oschlh mutant leaves than in wild-type leaves; this increase was largely caused by the impairment of the expression of the antioxidant genes, such as OsAPXl, OsRACl, and OsAOXc in knockout plants. Moreover, treatment of mesophyll protoplasts with ascorbic acid or catalase recovered ATP content in the mutants. Taken together, these results suggest that the light-mediated inhibition of mitochondrial activity leads to stunted growth of CHLH rice seedlings.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.72-72
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• 2017

We found a new stay-green mutant from 'Pyeongwon' which is an early-maturing rice variety in Korea. The mutant showed green leaves after grain ripening period and it maintained higher SPAD value than wild type rice plant and original variety 'Pyeongwon'. The stay-green trait in rice, three genes have been identified up to date. The non-yellow coloring1 (NYC1) gene encodes a chloroplast-localized short-chain dehydrogenase/reductase (SDR) with three transmembrane domains. The non-yellow coloring3 (NYC3) gene encodes a plastid-localizing alpha/beta hydrolase-fold family protein with an esterase/lipase motif. The Sgr gene encodes a novel chloroplast protein and regulates the destabilization of the light-harvesting chlorophyll binding protein (LHCP) complexes of the thylakoid membranes, which is a prerequisite event for the degradation of chlorophylls and LHCPs during senescence. After sequencing the PCR products, we found a single nucleotide variation($A{\rightarrow}T$) in the NYC1 gene, which changes the amino acid lysine to methionine. The NYC1 gene encodes a short-chain dehydrogenase/reductase(SDR) protein. And we confirmed the co-segregation between SNP and stay-green trait from genotyping the progenies of the mutant.

• Molecules and Cells
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• 제28권5호
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• pp.463-472
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• 2009

Although the possible cellular roles of several ubiquitin-specific proteases (UBPs) were identified in Arabidopsis, almost nothing is known about UBP homologs in rice, a monocot model plant. In this report, we searched the rice genome database (http://signal.salk.edu/cgi-bin/RiceGE) and identified 21 putative UBP family members (OsUBPs) in the rice genome. These OsUBP genes each contain a ubiquitin carboxyl-terminal hydrolase (UCH) domain with highly conserved Cys and His boxes and were subdivided into 9 groups based on their sequence identities and domain structures. RT-PCR analysis indicated that rice OsUBP genes are expressed at varying degrees in different rice tissues. We isolated a full-length cDNA clone for OsUBP6, which possesses not only a UCH domain, but also an N-terminal ubiquitin motif. Bacterially expressed OsUBP6 was capable of dismantling K48-linked tetra-ubiquitin chains in vitro. Quantitative real-time RT-PCR indicated that OsUBP6 is constitutively expressed in different tissues of rice plants. An in vivo targeting experiment showed that OsUBP6 is predominantly localized to the nucleus in onion epidermal cells. We also examined how knock-out of OsUBP6 affects developmental growth of rice plants. Although homozygous T3 osubp6 T-DNA insertion mutant seedlings displayed slower growth relative to wild type seedlings, mature mutant plants appeared to be normal. These results raise the possibility that loss of OsUBP6 is functionally compensated for by an as-yet unknown OsUBP homolog during later stages of development in rice plants.

• 한국식품영양과학회지
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• 제43권9호
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• pp.1388-1393
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• 2014

선행연구에서 얻은 alkalophilic Bacillus I-5 유래의 CGTase wild-type과 가수분해능이 강화된 mutant 효소를 활용하여 waxy rice starch로부터 아밀로펙틴 클러스터를 제조하였다. SEC-MALLS-RI 분석법으로 CGTase wild-type과 mutant 효소가 처리된 시료의 평균 분자량을 확인한 결과 10분가량의 효소반응으로 두 반응 모두 평균 분자량은 $10^4{\sim}10^5Da$으로 급격히 감소하였음을 확인하였으며, 일정 반응 시간이 경과한 이후에는 더 이상 분자량의 감소가 일어나지 않음으로 미루어 시료가 아밀로펙틴 클러스터 단위로 분해되었으며 그 분자량은 $10^4{\sim}10^5Da$ 정도임을 알 수 있다. 또한 MALDI-TOF/MS 분석을 통하여 CGTase wild-type은 다양한 종류의 cyclic 형태의 maltodextrin을 생성하고 있으며 mutant 효소는 주로 소량의 maltooligosaccharide 들을 생산함을 확인하였다.

• 한국작물학회지
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• 제51권4호
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• pp.348-355
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• 2006

Phenotypes of panicle, hull and seed of mutant rice (Oryza sativa L.) were characterized. Panicle mutants were classified in 4 groups with their internode length of main rachis, primary rachis, secondary rachis and pedicel. Hull and seed mutants were grouped into 12 based on their mutant characters in shape, size and color of seeds. These natural and spontaneous mutant collections showed distinct phenotypes to wild type rice. This might be useful for the identification of the functions of genetic factors in the Mendelian inheritance.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.110-110
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• 2017

Stomata are the main gateways for water and air transport between leaves and the environment. Inward-rectifying potassium channels regulate photo-induced stomatal opening. Rice contains three inward rectifying shaker-like potassium channel proteins, OsKAT1, OsKAT2 and OsKAT3. Among these, only OsKAT2 is specifically expressed in guard cells. Here, we investigated the functions of OsKAT2 in stomatal regulation using three dominant negative mutant proteins, OsKAT2(T235R), OsKAT2(T285A) and OsKAT2(T285D), which are altered in amino acids in the channel pore and at a phosphorylation site. Yeast complementation and patch clamp assays showed that all three mutant proteins lost channel activity. However, among plants overexpressing these mutant proteins, only plants overexpressing OsKAT2(T235R) showed significantly less water loss than the control. Moreover, overexpression of this mutant protein led to delayed photo-induced stomatal opening and increased drought tolerance. Our results indicate that OsKAT2 is an inward-rectifying shaker-like potassium channel that mainly functions in stomatal opening. Interestingly, overexpression of OsKAT2(T235R) did not cause serious defects in growth or yield in rice, suggesting that OsKAT2 is a potential target for engineering plants with improved drought tolerance without yield penalty.

• Preventive Nutrition and Food Science
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• 제11권1호
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• pp.78-83
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• 2006

A simplex-lattice mixture design was applied to blend three varieties of rice; Ilpum (IP), Goami2 (G2) and Baegjinju (BJJ) all of which have very different physicochemical properties from one another. G2 and BJJ are mutant rice developed from IP. Increasing G2 portions in a rice blend increases indigestible carbohydrate contents. Blending at least 33.3% of G2 to either IP or BJJ increased indigestible carbohydrates, which were approximately $3.55{\pm}1.31\;to\;4.57{\pm}0.37$(g/100 g), respectively. Consumers rated higher than 6.0 (=like slightly) for the IP alone and binary blends of IP and BJJ, whereas less than 5.0 (=dislike moderately) for the blends containing G2 rice, indicating that consumers would not accept rice blends containing higher G2 portions. However, although blends with G2 were given lower consumer ratings, a rice blend with G2 could have health benefits in terms of nutritional and functional properties due to the higher indigestible carbohydrate contents.

• Molecules and Cells
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• 제27권5호
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• pp.563-570
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• 2009

We previously isolated the OsCBT gene, which encodes a calmodulin (CaM)-binding protein, from a rice expression library constructed from fungal elicitor-treated rice suspension cells. In order to understand the function of OsCBT in rice, we isolated and characterized a T-DNA insertion mutant allele named oscbt-1. The oscbt-1 mutant exhibits reduced levels of OsCBT transcripts and no significant morphological changes compared to wild-type plant although the growth of the mutant is stunted. However, oscbt-1 mutants showed significant resistance to two major rice pathogens. The growth of the rice blast fungus Magnaporthe grisea, as well as the bacterial pathogen Xanthomonas oryzae pv. oryzae was significantly suppressed in oscbt-1 plants. Histochemical analysis indicated that the hypersensitive-response was induced in the oscbt-1 mutant in response to compatible strains of fungal pathogens. OsCBT expression was induced upon challenge with fungal elicitor. We also observed significant increase in the level of pathogenesis-related genes in the oscbt-1 mutant even under pathogen-free condition. Taken together, the results support an idea that OsCBT might act as a negative regulator on plant defense.