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Zoysia japonica Steud. is a warm-season lawn grass popular in Korea and elsewhere. They are cultivated in many places such as river banks, roadside, and play grounds. However, there still is a disadvantage of frequent mowing, and the grass grows poorly under the chilly conditions. To develop a grass variety that circumvents these drawbacks, we cloned the chitin-inducible gibberellins-responsive1 gene (CIGR1) from zoysiagrass. The full length of the ZjCIGR1 (Zj; Zoysia japonica Steud.) gene was obtained by 5′/3′ RACE PCR and the phylogenetic tree showed that it belonged to the CIGR1-subgroup in the PAT1-group of GRAS protein family. Expression of the ZjCIGR1 in wild-type plants was confirmed in roots, meristems, leaves, and flowers, especially high in the flowers. The transgenic zoysiagrass was confirmed by PCR using gene-specific primers, phosphinothricin-acetyl-transferase (PAT) strip test, and Southern blot analysis. ZjCIGR1-overexpressing plants acquired tolerance to cold stress displaying morphological phenotypes characteristic of stress resistance. In addition, in the transformants, expression of the ZjCIGR1 as well as cold-regulated (COR) gene was increased compared to the wild-type plants under cold stress condition. These results suggest that ZjCIGR1 gene is an important candidate for regulating cold stress resistance.

Insect-resistant Agb0101 rice was recently developed by modifying the cry1ac1 gene by changing codon usage changes relative to the native truncated cry1ac1 gene. To assess the toxicity of genetically modified Agb0101 rice, we conducted bioinfomational comparisons of the amino acid sequences that are not similar to known toxic proteins. Sufficient quantities of mCry1Ac1 protein were produced in Escherichia coli for in vitro evaluation and animal study. We compared the amino acid sequences and molecular mass. There have the same amino acid sequences and molecular masses after purifying the modified Cry1Ac1 (mCry1Ac1) protein from highly expressed bacteria and genetically modified rice were identical. We also investigated the acute and 90-days oral toxicities. No adverse effects were observed in mice following acute oral exposure to 2,000 mg/ kg body weight mCry1Ac1 protein of body weight and 90 days oral exposure to Agb0101. These results indicate that mCry1Ac1 proteins and Agb0101 rice demonstrate no adverse effects in these tests when applied via gavage and feed, respectively. Key words: Modified Cry1Ac1, food safety assessment, toxicity, insect- resistant rice Agb0101.

Most Bt transgenic rice events have an underlying grain cost depending on the insect pressure in the field. This study was conducted (1) to determine if the cry1Ac/bar genetically modified (GM) rice (designated Agb0101) based on a Korean japonica rice cultivar has any underlying grain cost and (2) to develop cry1Ac/bar GM rice lines with yield performance similar to those of Korean elite cultivars via crossbreeding. A three-year field experiment showed that Agb0101 had a high underlying grain cost equivalent to 18% grain yield loss, and this cost was mainly due to the grain number per panicle. Moreover, it was found that the cry1Ac/bar transgene was inherited as a single dominant gene. BC1F4―F5 crossbred progeny derived from an anther culture of Agb0101―showed phenotypic resemblance to non-transgenic Korean elite cultivars, resulting in a decrease in the grain yield cost of Agb0101 from 27% to 10%. These results suggest that Bt-GM rice-oriented cross-fertilization with a non-GM elite cultivar followed by two- or threefold selection is a feasible method to minimize or remove the underlying grain cost of the Bt transgenic insect-resistant rice line.

Bakanae disease (BD) has emerged as a serious threat in almost all rice cultivation regions worldwide. Nampyeong is a Korean japonica rice variety known to be resistant to BD. In this study, quantitative trait locus (QTL) mapping was performed with F2 and F3 plants derived from a cross between the Nampyeong variety and a susceptible Korean japonica line, DongjinAD. First, resequencing of Nampyeong and DongjinAD was performed, which identified 171,035 single nucleotide polymorphisms (SNPs) between the two parental varieties. Using these SNPs, 161 cleaved amplified polymorphic sequence (CAPS) markers and six derived CAPS markers were developed; then, a genetic map was constructed from the genotypes of 180 plants from the DongjinAD/Nampyeong F2 plants. The total length of the constructed genetic map was 1386 cM, with an average interval of 8.9 cM between markers. The BD mortality rates of each F3 family were measured by testing 40 F3 progenies using in vitro seedling screening method. QTL analysis based on the genetic map and mortality rate data revealed a major QTL, qFfR1, on rice chromosome 1. qFfR1 was located at 89.8 cM with a logarithm of the odds (LOD) score of 22.7. Further, there were three markers at this point: JNS01033, JNS01037, and JNS01041. A total of 15 genes were identified with annotations related to defense against plant diseases among the 179 genes in the qFfR1 interval at 95% probability, thereby providing potential candidate genes for qFfR1. qFfR1 and its closely linked markers will be useful in breeding rice varieties resistant to BD.

Four transgenic rice lines harboring insect-resistant gene cry3A showed ideal field performances characterized by high considerable resistance to rice water weevil ( Lis-sorhoptrus oryzophilus Kuschel). In this study, we estimated the insertion number of foreign genes, and analyzed the flanking sequences of T-DNAs in rice genome. As a result, T-DNA of BT12R1 line was inserted in exon region of rice chromosome 10. Two copies of T-DNAs were inserted in line BT12R2. BT12R3 line was analyzed at only left border flanking sequence. BT12R4 line was confirmed one copy of foreign gene insertion at the position 24,516,607 ~ 24,516,636 of rice chromosome 5, accompanied by a deletion of 30 bp known genomic sequences. This intergenic position was confirmed none of expressed gene and any deletion/addition of T-DNA sequence. In conclusion, these molecular data of rice water weevil resistant Bt rice would be used to conduct the biosafety and environment risk assessment for GM crop commercialization.

Stacked genetically modified (GM) crops are becoming popular for their enhanced production efficiency and improved functional properties. In this study, we developed an event-specific PCR method for simple qualitative detection of stacked events combining more than 2 transgenic traits. Ten primer sets were designed, including 9 that were event-specific and 1 that was specific for a maize endogenous gene. Five event-specific multiplex-PCR systems were built, based on the main type of stacked GM events approved in Korea. Multiplex PCR was performed with mixtures of template DNA extracted from certified reference materials. PCR amplicons (3 or 4 by type) of expected sizes and mutually similar intensities were detected. The limit of detection was approximately 0.1%(v/v) for stacked GM maize in all event-specific PCRs. This method may be useful for the specific detection and monitoring of stacked GM maize lines and individual parent GM maize lines, by effectively distinguishing genestacked events.

The rice water weevil (RWW), Lissorhoptrus oryzophilus Kuschel, is the most widely distributed and destructive early season insect pest of rice, Oryza sativa L. worldwide. The rice plants were transformed with cryIIIA insecticidal gene as well as with the bar gene coding phosphinothricin acetyltransferase. CryIIIA gene under the control of a modified RCg2 promoter drives the insect-toxic gene expression in roots and/or leaves. The cryIIIA gene was transferred into O. sativa L. cv. Nakdong by Agrobacterium-mediated transformation. Stable integration of the transgene was confirmed in putative transformed rice by Southern blot analysis. The expression of the cryIIIA toxin gene in the roots of transgenic rice plants was verified by RT-PCR and immunoblot analysis. Transgenic rice plants were also evaluated for resistance to natural infestations of the RWW under field conditions between 2007 and 2011. The transgenic Btt8R and Btt12R lines reduced the growth rate of RWW larvae and pupae populations compared with non-transgenic control plants by approximately 52 and 58 %, respectively. To further examine the efficacy of the RWW bioassay, we used pots and performed experiments in trays and under field conditions in 2012. The Btt12R line reduced the total populations of RWW larvae and pupae in trays and under field conditions by 56 and 45 %, respectively. The bioassay experiments conducted over 6 years, showed a significant reduction rate of RWW larvae and pupae populations demonstrating that the cryIIIA gene in transgenic rice confers resistance to RWW.

본 연구는 종자로부터 유도된 캘러스를 아그로박테리움을 이용해 감염하여 고체배지에서 배양하는 기존의 방법과 달리, 형질전환에 소모되는 노동력과 시간, 비용을 단축하고자 감염과 공동배양, 균제거와 캘러스 선발까지 액체배양을 시도하였다. 성숙 종자로부터 유도된 캘러스를 바로 아그로박테리움으로 감염함으로써 조직배양으로 인한 체세포 변이의 발생을 최소화하고 감염부터 그 후 캘러스선발까지 총 4단계의 시간과 비용을 최소화하였으며, 감염된 캘러스로부터 재분화 시킴으로써 형질전환 식물체를 얻는 방법을 새롭게 수립하였다. 배양과정 중 감염과 공동배양 기간을 3일로 단축시킴으로써 캘러스의 스트레스를 최소화 하였고, PCR 분석을 통해 원하는 목표 유전자가 형질전환체에 안정적으로 도입이 되는 것도 확인할 수 있었다. 이러한 결과를 종합해 볼 때, 본 실험을 통해 얻어진 새로운 액체배양 방법은 우수한 농업적 형질을 가진 벼 품종 개발시 효율적으로 이용할 수 있을 것으로 생각된다. 【Rice is one of the most important cereal crops as a model plant for functional genomics of monocotyledons and usually transformed using Agrobacterium tumefaciens. However, the transformation's process using previous method is still time consuming and uneconomical, low efficiency. In this study, we established a new method by modifying the general Agrobacterium protocol especially in the infection and co-cultivation, Agrobacterium elimination, infected calli's selection steps using liquid media. We directly inoculated Agrobacterium containing a ZjLsL gene under the control of constitutive promoter into the 1- to 3-week-old rice calli derived from mature seeds. After 3 days of co-cultivation, the infected calli were transferred onto liquid media of Agrobacterium elimination and calli's selection for 3 days. The calli were transferred to calli's growth solid media for 14 days and then the calli transferred to shoot induction and root induction media. Putative transformants were initially selected on the medium containing phosphinothricin, and the PAT protein verified by PAT strip test. This method in this study would lead to reduction of substantial labor and time to generate transgenic plants.】

Insect-resistant transgenic rice was developed by inserting the mCry1Ac1 a modified gene fromthe soil bacterium Bacillus thuringiensis (Bt). For biosafety assessment, we studied the effects onsurvival of cantor Daphnia magna, a commonly used as a model organism in ecotoxicologicalstudies. D. magna fed on Bt rice and its near non-genetically modified (GM) counterparts(Nakdong) grown in the same environment (100% ground rice suspension). The Bt rice wascomfirmed to have the insertion of T-DNA and protein expression by the polymerase chainreaction and ELISA analysis. Feeding study showed similar cumulative immobility and abnormalresponse of D. magna between Bt rice and non-GM counterparts. 48 h-EC

A novel genetically modified organism (GMO) detection method was developed using a simple and rapid procedure to identify a regulatory gene introduced into genetically modified (GM) maize. After DNA extraction from GM maize flours, fragments of the conserved sequence of the cauliflower masaic virus (CaMV) 35S promoter gene along with a competitive internal control gene were amplified using duplex polymerase chain reaction (PCR). Amplification products were then detected using a disposable detection device. The quantitative detection limit for GM maize 59122 was found to be 1.0% (w/w). Because the combination-method involving PCR technology coupled with a disposable detection device does not require expensive instrumentation or expertise, it will serve as a valuable alternative to immunoassays and traditional PCR-based tests in the detection of GMOs.

The development of marker-free transgenic plants has responded to public concerns over the safety of biotechnology crops. It seems that continued work in this area will soon remove the question of unwanted marker genes from the debate concerning the public acceptability of transgenic crop plants. Selectable marker genes are co-introduced with genes of interest to identify those cells that have integrated the DNA into their genome. Despite the large number of different selection systems, marker genes that confer resistance to the antibiotics, hygromycin (hpt) and kanamycin (nptII) or herbicide phosphinothricin (bar), have been used in most transgenic research and crop development techniques. The techniques that remove marker gene are under development and will eventually facilitate more precise and subtle engineering of the plant genome, with widespread applications in both fundamental research and biotechnology. In addition to allaying public concerns, the absence of resistance genes in transgenic plants could reduce the costs of developing biotechnology crops and lessen the need for time-consuming safety evaluations, thereby speeding up the commercial production of biotechnology crops. Many research results and various techniques have been developed to produce marker-free transgenic plants. This review describes the strategies for eliminating selectable marker genes to generate marker-free transgenic plants, focusing on the three significant marker-free technologies, co-transformation, site-specific recombinase-mediated excision, and non-selected transformation.

Composition analysis of genetically modified crops is an important consideration in the assessment of food safety. Agb0101 (Oryza sativa L. cv. Nakdongbyeo) developed in Korea is a form of insect-resistant rice that contains a synthetic truncated cry1Ac gene isolated from Bacillus thuringiensis (Bt), and demonstrates high resistance to rice leaf folder under field conditions. Nutrients, anti-nutritive components, and secondary metabolites of Agb0101 were analyzed and compared with those of its non-transgenic counterpart. The amounts of proximates, amino acids, fatty acids, minerals, vitamins, trypsin inhibitors, phytic acid, and ferulic acid in brown rice from Agb0101 were comparable to those of its non-transgenic counterpart. Statistical comparisons to test for equivalence showed that all the analyzed components in the insect-resistant rice plants were substantially equivalent to those of its non-transgenic counterpart. Furthermore, most of the measured values from Agb0101 were within the range of values reported for other commercial rice varieties.

Lactoferrin is an 80-kDa iron-binding glycoprotein that is found in high concentrations in human milk. Human lactoferrin (hLF) has several beneficial biological activities including immune system modulation and antimicrobial activity. In the present study, we devolved a method of hLF expression through introducing the hLF gene construct into Oriza sativa cv. Nakdong using the Agrobacterium-mediated transformation system. The expression of the hLF gene under the control of the rice glutelin promoter was detected in the seeds of transgenic rice plants. Transformed rice plants were selected on media containing herbicide(DL-phosphinothricin) and the integration of hLF cDNA was confirmed by Southern blot analysis. The expression of the full length hLF protein from the grains of transgenic rice plants was verified by Western blot analysis. The lactoferrin expression levels in the transformed rice grains determined by enzyme-linked immunosorbant assay accounted for approximately 1.5% of total soluble protein. Taken together, these data indicate that rice grains expressing hLF can be directly incorporated into infant formula and baby food.

Coordination of multiple transgenes is essential for metabolic engineering of biosynthetic pathways. Here, we report the utilization of two bicistronic systems involving the 2A sequence from the foot-and-mouth disease virus and the internal ribosome entry site (IRES) sequence from the crucifer-infecting tobamovirus to the biosynthesis of carotenoids in rice endosperm. Two carotenoid biosynthetic genes, phytoene synthase (Psy) from Capsicum and carotene desaturase (CrtI) from Pantoea, were linked via either the synthetic 2A sequence that was optimized for rice codons or the IRES sequence under control of the rice globulin promoter, generating PAC (Psy-2A-CrtI) and PIC (Psy-IRES-CrtI) constructs, respectively. The transgenic endosperm of PAC rice had a more intense golden color than did PIC rice, demonstrating that 2A was more efficient than IRES in coordinating gene expression. The 2A and IRES constructs were equally effective in driving transgene transcription. However, immunoblot analysis of CRTI, a protein encoded by the downstream open reading frame of the bicistronic constructs, revealed that 2A was ninefold more effective than IRES in driving translation. The PAC endosperms accumulated an average of 1.3 μg/g of total carotenoids, which was ninefold higher than was observed for PIC endosperms. In particular, accumulation of β-carotene was much higher in PAC endosperms than in PIC endosperms. Collectively, these results demonstrate that both 2A and IRES systems can coordinate the expression of two biosynthetic genes, with the 2A system exhibiting greater efficiency. Thus, the 2A expression system described herein is an effective new tool for multigene stacking in crop biotechnology.

Selectable marker gene systems are vital for the development of transgenic plants, but the presence of selectable marker genes encoding antibiotic or herbicide resistance in genetically modified plants poses a number of problems. A lot of research results and various techniques have been developed to produce marker-free GM plants. The aim of this review is to describe the principal methods used for eliminating selectable marker genes to generate marker-free GM plants, concentrating on the three significant methods(co-transformation, site-specific recombinase-mediated ex-cision, non-selected transformation) in several marker-free techniques. 서 론 1996년 처음 상업화된 유전자변형 (Genetically Modified, GM) 작물의 재배면적은 매년 급속한 성장을 기록하여 2009년에는 25개국 1억 3천 4백만 헥타르에 이르고 있다(James 2009). 이와 같은 GM작물의 성장세는 개발도상국과 선진국의 재배농민 모두에게 GM작물이 경제적으로 도움이 되며 식물형질전환기술의 급속한 발전으로 주요작물에서 높은 효율로 형질전환 (transformation)이 가능해졌기 때문이다. GM작물 개발을 위한 식물형질전환기술의 급속한 발전은 새로운 배지나 형질전환법의 개발이 빠르게 이루어졌기 때문이기도 하지만, 항생제 내성 유전자와 같은 선발표지 시스템을 식물형질전환에 적용했기 때문이다 (Miki and McHung 2004). 일반적으로 식물체 내에 목적유전자를 형질전환하기 위해서는 운반체 (vector)라는 DNA 구성물을 사용하여 목적유전자와 함께 항생제 내성 유전자와 같은 선발표지 유전자를 토양미생물인 아그로박테리움 (

Although susceptibility to seed shattering causes severe yield loss during cereal crop harvest, it is an adaptive trait for seed dispersal in wild plants. We previously identified a recessive shattering locus, sh-h, from the rice shattering mutant line Hsh that carries an enhanced abscission layer. Here, we further mapped sh-h to a 34-kb region on chromosome 7 by analyzing 240 F(2) plants and five F(3) lines from the cross between Hsh and Blue&Gundil. Hsh had a point mutation at the 3' splice site of the seventh intron within LOC_Os07g10690, causing a 15-bp deletion of its mRNA as a result of altered splicing. Two transferred DNA (T-DNA) insertion mutants and one point mutant exhibited the enhanced shattering phenotype, confirming that LOC_Os07g10690 is indeed the sh-h gene. RNA interference (RNAi) transgenic lines with suppressed expression of this gene exhibited greater shattering. This gene, which encodes a protein containing a conserved carboxy-terminal domain (CTD) phosphatase domain, was named Oryza sativa CTD phosphatase-like 1 (OsCPL1). Subcellular localization and biochemical analysis revealed that the OsCPL1 protein is a nuclear phosphatase, a common characteristic of metazoan CTD phosphatases involved in cell differentiation. These results demonstrate that OsCPL1 represses differentiation of the abscission layer during panicle development.

The insecticidal toxin gene of Bacillus thuringiensis (Bt) is one of the most commonly used in the development of genetically modified (GM) crops. In this research, we analyzed Bt rice showing lepidopteran pest-resistance. The Bt gene is a synthetic Cry1Ac composed of optimal codons for plants, and the Bt protein is targeted to the chloroplast by a transit peptide. Three Cry1Ac rice events (C103-3, C127-1, and C7-1) were analyzed for molecular characterization. C103-3 contains two copies of T-DNA where the left border (LB) region is truncated. Both C7-1 and C127-1 have a single copy of T-DNA, but a part of the vector backbone DNA is inserted into the genome of C127-1; thus, only C7-1 had intact T-DNA. Progenies of C7-1 crossed with the original cultivar, Nakdong, and double-haploid lines from anther culture of lines crossed with the elite cultivar, Dongjin, were analyzed for T-DNA flanking genomic DNA and genotyping. Results showed that an intact T-DNA region without the vector backbone was inserted into the genome and was stably inherited through generations. The C7-1 homozygous event could be used as breeding material to develop GM rice with pest resistance.

In recent years, several genetically modified (GM) crops have been developed worldwide through the recombinant DNA technology and commercialized by various agricultural biotechnological companies. Commercialization of GM crops will be required the assesment of risks associated with the release of GM crops. In advance of the commercial release of GM crops, developer should submit the several information on GM crops for approval. In this study, we carried out to provide the molecular data for the risk assessment of GM rice containing insect-resistant gene, modified Cry1Ac (CryIAc1). Through the molecular analysis with CryIAc1 induced GM rice, we confirmed the steady integration and expression of transgene, the transgene copy number, the adjacent region sequences of inserted gene into rice genome, and the transgene stability in progenies. For the qualitative PCR detection methods, specific primer pairs were designed on the basis of integration sequences, and construct- and event-specific detection markers were developed for leaf folder-resistant rice, Cr7-1 line. From these results, we demonstrated that the molecular data and the PCR detection methods of leaf folder- resistant GM rice could be acceptable to conduct the biosafety and environment risk assessment.

A gene encoding a putative guanosine 5′-diphosphate (or 5′-triphosphate) 3′-diphosphate ((p)ppGpp) synthetase, designated PepRSH ( Pep per RelA / SpoT homologue), was isolated from hot peppers. PepRSH was found to contain five introns and six exons and a 2166-bp open reading frame encoding a protein of 721 amino acids; this protein displayed significant homology with other plant (p)ppGpp synthetases. A genomic DNA gel blot analysis revealed that the pepper genome has at least a single copy of PepRSH . PepRSH transcripts were highly accumulated in non-host resistance response-induced leaves and in leaves following induction with salicylic acid, methyl jasmonate, wounding, hydrogen peroxide, and ultraviolet-B. The expression of PepRSH was also influenced by abiotic stresses, such as flooding and high salinity. The deduced PepRSH protein has a putative chloroplast-targeting transit peptide at its N-terminus, and immunolocalization studies verified the translocation of PepRSH to the chloroplast. The predicted PepRSH protein is markedly similar to known plant and bacterial RSH proteins. Expression of a putative (p)ppGpp synthetase domain in an Escherichia coli single mutant ( RelA − SpoT + ) complemented growth of the mutant but not of an E. coli double mutant ( RelA − SpoT − ), demonstrating that PepRSH has (p)ppGpp synthetase activity only in the (p)ppGpp synthetase domain. Site-directed mutagenesis of the conserved histidine and aspartic acid (HD) site in the putative HD domain of PepRSH revealed that the histidine and aspartic acid dual sites were critical residues for the (p)ppGpp synthetase activity of PepRSH protein. Mutation of the HD site limited the tolerance of bacteria to both salt and osmotic stress. Our results indicate that pepper plants have a (p)ppGpp regulatory system that is similar to that of bacteria and which may transduce stress-related signals through the regulation of (p)ppGpp by PepRSH localized in chloroplasts.

For the development of qualitative PCR detection method of genetically modified (CM) rice, rice species-specific gene, OsCc-1 (rice cytochrome c gene), was selected as suitable far use as an endogenous gene in rice. The primer pair OsCytC-5`/3`with 111 bp amplicon was used for PCR amplification of the rice endogenous gene, OsCc-1 and no amplified product was observed from 8 different crops as templates. Qualitative PCR method was carried out with stack traits of L528CryIAc1 GM rice developed in Korea. For the qualitative PCRs, some primer pairs were designed with a construct-specific and event-specific type based on T-DNA and junction sequences of T-DNA in GM rice. Actck-5`/3` amplifying between actin promoter and OsCK1 gene introduced in LS28 gave rise to an amplicon 306 bp; also, CrLB-5`/3` from CryIAcl and CKRB-5`/3`amplifying the junction region of T-DNA and genome sequence from LS28 as event-specific primers gave rise to an amplicon 142 bp and 91 bp, respectively. These primer pairs for the detection of event-specific targets not produced PCR amplicons on non-CM rice and various crops in contrast to event lines. Therefore, in this study we verified that event-specific primers were effective to specifically detect stack trait lines and demonstrated that this method presented could be provided with the detection-method data for risk assessment analysis of GM rice to be commercialized.

Using an F 2:3 population with 200 lines derived from a cross between the japonica rice ( Oryza sativa L.) varieties Gaochan 106 and Changbai 9, quantitative trait loci (QTLs) for root number, root length, seedling height, and their relative alkaline damage rates at early seedling stage were identified under 0.15% Na 2 CO 3 alkaline stress. A total of 26 QTLs associated with these traits were detected on chromosomes 1, 5, 6, 7, 8, 9, and 11, consisting of 4 QTLs for root number, 5 QTLs for relative alkaline damage rate of root number, 6 QTLs for root length, 2 QTLs for relative alkaline damage rate of root length, 5 QTLs for seedling height, and 4 QTLs for relative alkaline damage rate of seedling height. QTLs qRN6-1 , qRN11 , qRRN11-2 , qRRL11-2 , qSH1 , qSH11-2 , qRSH5 , and qRSH6-2 accounted for 29.91, 13.42, 23.86, 21.06, 15.81, 16.53, 29.89, and 34.63% of the phenotypic variations, respectively. These QTLs, except for qRN6-1 with the marker flanking distance of 19.0 cM, were located with relatively large marker flanking distances over 26.3 cM. The positive alleles at 13 loci originated from the tolerant parent Changbai 9, and the positive alleles at other loci were from the sensitive parent Gaochan 106. Partial dominance and over dominance were the main effects at these loci.

Transposon-mediated insertional mutagenesis is one of powerful strategy for assessing functions of genes in higher plants. In this report, we have selected highly susceptible and tolerance plant by screening about high salt (3% NaCl) and cold stresses () from F2 seeds of 30,000 Ac/Ds insertional mutagenesis lines in rice (Oryza sativa L. cv. Dongjin). In order to identify the gene tagging, insertion of Ds element was analyzed by Southern blot and these results revealed that 19 lines were matched genotype of selected lines with phenotype from the first selected 212 lines, and 13 lines have one copy of Ds elements. The Franking Sequence Tags (FSTs) of selected mutant lines showed high similarities with the following known function genes: signal transduction and regulation of gene expression (transpoter, protease family protein and apical meristem family protein), osmotic stress response (heat shock protein, O-methyltransferase, glyceraldehyde-3-phosphate dehydrogenase and drought stress induce protein), vesicle trafficking (SYP 5 family protein) and senescence associated protein. The expression pattern of 19 genes were analyzed using RT-PCR under the abiotic stresses of 9 class; 250mM NaCl, osmotic, drought, 3% , ABA, IAA, 0.1 ppm 2,4-D, cold and high temperature. Isolated knock-out genes showed the positive response about 250 mM NaCl, drought, , PEG, IAA, 2,4-D, ABA treatment and low () and high temperature (). The results from this study indicate that function of selected knock-out genes could be useful in improving of tolerance to abiotic stresses as an important transcriptional activators in rice.

Tocopherols are essential lipophilic antioxidant in human cells, while little is known about its function in plant tissues. To study the impact of composition and content of tocopherols on stress tolerance, tobacco (Nicotiana tabacum) was transformed with a construct containing a cDNA insert encoding -tocopherol methyltransferase (-TMT/VTE4) from perilla under the control of the cauliflower mosaic virus (CaMV) 35S promoter. The transgenic tobacco was confirmed by PCR and RT-PCR. The total content and composition of tocopherols in the transgenic lines were similar with wild type controls. However, chlorophyll-a and carotenoid content in the transgenic lines were increased by up to 45% (P-TMT increased the salt stress tolerance in tobacco plants. These results demonstrate that over-expression of -TMT gene in tocopherol bio-synthetic pathway can increase salt stress tolerance and contents of chlorophyll-a and carotenoid in transgenic tobacco plants.

본 연구는 동진벼 유래의 Ac/Ds 삽입변이집단의 GUS 분석을 통하여 뿌리 및 미숙종자에서 강하게 GUS가 발현한 개체를 선발하여 FST(flanking sequence tag) 분석 한 결과 Ds 전이 인자가 3번 염색체 zinc finger RING-H2 관련 Oszinc626 유전자의 첫 번째 exon 부위에 single copy로 삽입되어 있었으며, 선발변이체는 뿌리 및 종자 발달이 정상인 동진벼에 비해 매우 낮은 것으로 나타났다. Oszinc626 유전자는 RING-H2 type(C3-H2-C3)으로 $Cys-X_2-Cys-X_{28}-Cys-X-His-X_2-His-X_2-Cys-X_{14}-Cys-X_2-Cys$ 배열이 C-terminus 가장 말단에 위치하며, 49 kDa의 분자량을 가지고 있다. 또한 Southern blot 분석에서 Oszinc626 유전자는 벼 게놈상에 single copy로 존재하였다. RT-PCR을 통한 돌연변이 유전자의 발현분석 결과 250 mM의 염과, $4^{\circ}C$ 저온등과 같은abiotic stress에 의해 발현이 증가함을 보였고, 호르몬처리에 있어서 ABA와 IAA의 식물호르몬을 처리했을 경우 24시간까지 계속해서 발현양이 증가하는 것을 보이는 반면, 2,4-D 처리의 경우 30분 후에 발현이 일시적으로 증가되었으나 이후 발현이 급속히 감소한 것을 보였다. 벼의 조직 별 발현 검정에서 미성숙한 종자, 뿌리 분열조직 및 신초 등 주로 생장점 부위에서 강하게 발현되는 것을 보임에 따라 Oszinc626 유전자의 경우 식물의 생장에 관여하는 주동 유전자의 하나로 판단된다. 【Ac/Ds mutant lines of this study were transgenic rice plants, each of which harbored the maize transposable element Ds together with a GUS coding sequence under the control of a promoterless(Ds-GUS). We selected the mutants that were GUS expressed lines, because the GUS positive lines will be useful for identifying gene function in rice. One of these mutants was identified knock-out at Oszinc626(NP_001049991) gene, encoding a RING-H2 zinc-finger protein, by Ds insertion. In this mutant, while primary root development is normal, secondary root development from lateral root was very poor and seed development was incomplete compare with normal plant. RING zinc-finger proteins play important roles in the regulation of development in a variety of organisms. In the plant kingdom, a few genes encoding RING zinc-finger proteins have been documented with visible effects on plant growth and development. The consensus of the RING-H2(C3-H2-C3 type) domain for this group of protein is $Cys-X_2-Cys-X_{28}-Cys-X-His-X_2-His-X_2-Cys-X_{14}-Cys-X_2-Cys$ . Oszinc626 encodes a predicted protein product of 445 amino acids residues with a molecular mass of 49 kDa, with a RING-zinc-finger motif located at the extreme end of the C-terminus. RT-PCR analysis indicated that the expression of Oszinc626 gene was induced by IAA, cold, dehydration, high-salinity and abscisic acid, but not by 2,4-D, and the transcription of Oszinc626 gene accumulated primarily in rice immature seeds, root meristem and shoots. The gene accumulation patterns were corresponded with GUS expression.】

The Korean Rice Ds-tagging lines Database (KRDD) is designed to provide information about Ac/Ds insertion lines and activation tagging lines using japonica rice. This database has provided information on 18,158 Ds lines, which includes the ID, description, photo image, sequence information, and gene characteristics. The KRDD is visualized using a web-based graphical view, and anonymous users can query and browse the data using the search function. It has four major menus of web pages: (i) a Blast Search menu of a mutant line; Blast from rice Ds-tagging mutant lines; (ii) a primer de-sign tool to identify genotypes of Ds insertion lines; (iii) a Phenotype menu for Ds lines, searching by identi-fication name and phenotype characteristics; and (iv) a Management menu for Ds lines. Availability: The KRDD can be accessed at the web site of the National Institute of Agricultural Biotechnology (http://www. niab.go.kr/RDS/) Keywords: Ac/Ds database, Ds phenotype, Ds-tagging line, insertion line, KRDD

OSH6 (Oryza sativa Homeobox6) is an ortholog of lg3 (Liguleless3) in maize. We generated a novel allele, termed OSH6-Ds, by inserting a defective Ds element into the third exon of OSH6, which resulted in a truncated OSH6 mRNA. The truncated mRNA was expressed ectopically in leaf tissues and encoded the N-terminal region of OSH6, which includes the KNOX1 and partial KNOX2 subdomains. This recessive mutant showed outgrowth of bracts or produced leaves at the basal node of the panicle. These phenotypes distinguished it from the OSH6 transgene whose ectopic expression led to a "blade to sheath transformation" phenotype at the midrib region of leaves, similar to that seen in dominant Lg3 mutants. Expression of a similar truncated OSH6 cDNA from the 35S promoter (35S::DeltaOSH6) confirmed that the ectopic expression of this product was responsible for the aberrant bract development. These data suggest that OSH6-Ds interferes with a developmental mechanism involved in bract differentiation, especially at the basal nodes of panicles.

Insertional mutagen-mediated gene tagging populations have been essential resources for analyzing the function of plant genes. In rice, maize transposable elements have been successfully utilized to produce transposant populations. However, many generations and substantial field space are required to obtain a sufficiently sized transposant population. In rice, the japonica and indica subspecies are phenotypically and genetically divergent. Here, callus cultures with seeds carrying Ac and Ds were used to produce 89,700 lines of Dongjin, a japonica cultivar, and 6,200 lines of MGRI079, whose genome is composed of a mixture of the genetic backgrounds of japonica and indica. Of the more than 3,000 lines examined, 67% had Ds elements. Among the Ds-carrying lines, 81% of Dongjin and 63% of MGRI079 contained transposed Ds, with an average of around 2.0 copies. By examining more than 15,000 lines, it was found that 12% expressed the reporter gene GUS during the early-seedling stage. GUS was expressed in root hairs and crown root initials at estimated frequencies of 0.78% and 0.34%, respectively. The 5,271 analyzed Ds loci were found to be randomly distributed over all of the rice chromosomes.

A nonpathogenic rhizobacterium, Pseudomonas putida LSW17S, elicited systemic protection against Fusarium wilt and pith necrosis caused by Fusarium oxysporum f. sp. lycopersici and P. corrugata in tomato (Lycopersicon esculentum L.). LSW17S also confers disease resistance against P. syringae pv. tomato DC3000 (DC3000) on Arabidopsis ecotype Col-0. To investigate mechanisms underlying disease protection, expression patterns of defense-related genes PR1, PR2, PR5, and PDF1.2 and cellular defense responses such as hydrogen peroxide accumulation and callose deposition were investigated. LSW17S treatment exhibited the typical phenomena of priming. Strong and faster transcription of defense-related genes was induced and hydrogen peroxide or callose were accumulated in Arabidopsis treated with LSW17S and infected with DC3000. In contrast, individual actions of LSW17S and DC3000 did not elicit rapid molecular and cellular defense responses. Priming by LSW17S was translocated systemically and retained for more than 10 days. Treatment with LSW17S reduced pathogen proliferation in Arabidopsis ecotype Col-0 expressing bacterial NahG; however, npr1, etr1, and jar1 mutations impaired inhibition of pathogen growth. Cellular and molecular priming responses support these results. In sum, LSW17S primes Arabidopsis for NPR1-, ethylene-, and jasmonic acid-dependent disease resistance, and efficient molecular and cellular defense responses.

Cochliobolus miyabeanus forms a specialized infection structure, an appressorium, to infect rice. Contacting a hard surface induces appressorium formation in C. miyabeanus, while the hydrophobicity of the substratum does not affect this morphogenic infection event. To determine whether the calcium/calmodulin-dependent signaling system is involved in prepenetration morphogenesis in C. miyabeanus, the effects of a calcium chelator (ethylene glycol tetraacetic acid; EGTA), phospholipase C inhibitor (neomycin), intracellular calcium channel blocker (TMB-8), calmodulin antagonists (chlorpromazine, phenoxybenzamine, and W-7), and calcineurin inhibitor (cyclosporin A) on morphogenesis and infection were examined. Addition of Ca2+ and the calcium ionophore A23187 did not affect conidial germination, while the number of appressoria decreased with higher concentrations. EGTA inhibited conidial germination and appressorium formation. The calcium channel blocker did not affect appressorium formation at any concentration; however, calmodulin antagonists and the calcineurin inhibitor specifically reduced appressorium formation at the micromolar level. One of the calmodulin antagonists, W-7, also inhibited accumulation of mRNA of the calmodulin gene within germinating conidia and/or appressorium-forming germ tubes. Thus, biochemical processes controlled by the calcium/calmodulin signaling system seem to be involved in the induction of prepenetration morphogenesis on rice.

Ahn, I.-P., and Suh, S.-C. 2007. Calcium restores prepenetration morphogenesis abolished by methylglyoxal-bis-guanyl hydrazone in Cochliobolus miyabeanus infecting rice. Phytopathology 97:331-337. Cochliobolus miyabeanus forms a specialized infection structure, an appressorium, to infect its host rice plants. Curtailment of prepenetration development by spermidine and spermine was more evident in appressorium development and germination remained unaffected, whereas putrescine and methylglyoxal-bis-guanyl hydrazone (MGBG) impaired both morphogenetic events. Exogenous calcium nullified the inhibitory effect of MGBG on the prepenetration development in vitro and in vivo and the disease progression. High levels of polyamines were detected in freshly collected conidia, but the amounts were reduced during germination and appressorium formation. MGBG fortified the decrease of polyamines within conidia under development and calcium amendment did not affect the reduction. Hard-surface contact augmented messenger RNA synthesis of calmodulin gene (CmCaM) and protein kinase C (PKC) activity in germinating or appressorium-forming conidia. Calcium restored transcription of CmCaM and upregulation of PKC activity suppressed by MGBG. Taken together, fine-tuning of intracellular polyamine transition is indispensable for the conidial germination and appressorium formation in C. miyabeanus. Biochemical and molecular analyses revealed that the MGBG-acting site or sites are upstream of Ca2+-dependent signaling pathways regulating prepenetration morphogenesis of C. miyabeanus causing rice brown leaf spot. Additional keywords: Bipolaris oryzae, Oryza sativa.

Thiamine confers systemic acquired resistance (SAR) on susceptible plants through priming, leading to rapid counterattack against pathogen invasion and perturbation of disease progress. Priming reduces the metabolic cost required for constitutive expression of acquired resistance. To investigate the effects of priming by thiamine on defense-related responses, Arabidopsis (Arabidopsis thaliana) was treated with thiamine and effects of pathogen challenge on the production of active oxygen species, callose deposition, hypersensitive cell death, and pathogenesis-related 1 (PR1)/Phe ammonia-lyase 1 (PAL1) gene expression was analyzed. Thiamine did not induce cellular and molecular defense responses except for transient expression of PR1 per se; however, subsequent Pseudomonas syringae pv tomato challenge triggered pronounced cellular defense responses and advanced activation of PR1/PAL1 gene transcription. Thiamine treatment and subsequent pathogen invasion triggered hydrogen peroxide accumulation, callose induction, and PR1/PAL1 transcription activation in Arabidopsis mutants insensitive to jasmonic acid (jar1), ethylene (etr1), or abscisic acid (abi3-3), but not in plants expressing bacterial NahG and lacking regulation of SAR (npr1 [nonexpressor of PR genes 1]). Moreover, removal of hydrogen peroxide by catalase almost completely nullified cellular and molecular defense responses as well as SAR abolishing bacterial propagation within plants. Our results indicated that priming is an important cellular mechanism in SAR by thiamine and requires hydrogen peroxide and intact NPR1.

We isolated HvRAF (Hordeum vulgare root abundant factor), a cDNA encoding a novel ethylene response factor (ERF)-type transcription factor, from young seedlings of barley. In addition to the most highly conserved APETALA2/ERF DNA-binding domain, the encoded protein contained an N-terminal MCGGAIL signature sequence, a putative nuclear localization sequence, and a C-terminal acidic transcription activation domain containing a novel mammalian hemopexin domain signature-like sequence. Their homologous sequences were found in AAK92635 from rice and RAP2.2 from Arabidopsis; the ERF proteins most closely related to HvRAF, reflecting their functional importance. RNA blot analyses revealed that HvRAF transcripts were more abundant in roots than in leaves. HvRAF expression was induced in barley seedlings by various treatment regimes such as salicylic acid, ethephon, methyl jasmonate, cellulase, and methyl viologen. In a subcellular localization assay, the HvRAF-GFP fusion protein was targeted to the nucleus. The fusion protein of HvRAF with the GAL4 DNA-binding domain strongly activated transcription in yeast. Various deletion mutants of HvRAF indicated that the transactivating activity was localized to the acidic domain of the C-terminal region, and that the hemopexin domain signature-like sequence was important for the activity. Overexpression of the HvRAF gene in Arabidopsis plants induced the activation of various stress-responsive genes, including PDF1.2, JR3, PR1, PR5, KIN2, and GSH1. Furthermore, the transgenic Arabidopsis plants showed enhanced resistance to Ralstonia solanacearum strain GMI1000, as well as seed germination and root growth tolerance to high salinity. These results collectively indicate that HvRAF is a transcription factor that plays dual regulatory roles in response to biotic and abiotic stresses in plants.

Responses of rice to Magnaporthe grisea and Cochliobolus miyabeanus were compared. In Tetep, a rice cultivar resistant to both fungi, pathogen inoculation rapidly triggered the hypersensitive reaction (HR), resulting in microscopic cell death. In rice cv. Nakdong, susceptible to both pathogens, M. grisea did not cause HR, whereas C. miyabeanus caused rapid cell death similar to that associated with HR, which appeared similar to that observed in cv. Tetep, yet failed to block fungal ramification. Treatment with conidial germination fluid (CGF) from C. miyabeanus induced rapid cell death in both cultivars, suggesting the presence of phytotoxins in CGF. Pretreatment of cv. Nakdong with CGF significantly increased resistance to M. grisea, while the same treatment was ineffective against C. miyabeanus. Similarly, in cv. Nakdong, benzothiadiazole (BTH) significantly increased resistance to M. grisea, but was ineffective against C. miyabeanus. Methyl jasmonate (MeJA) treatment appeared to be ineffective against either fungus. Increased resistance of cv. Nakdong to M. grisea by BTH or CCF treatment was correlated with more rapid induction of three monitored PR genes. Application of MeJA resulted in the expression of JAmyb in cv. Nakdong being induced faster than in untreated plants in response to M. grisea infection. In contrast, the expression pattern of the PR and JAmyb genes in response to C. miyabeanus was nearly identical between cvs. Nakdong and Tetep, and neither BTH nor MeJA treatment significantly modified their expression patterns in response to C. miyabeanus infection. Our results suggest that rice employs distinct mechanisms for its defense against M. grisea versus C. miyabeanus.

An efficient protocol has been developed for rapid mass propagation of sweetpotato from shoot-tips derived embryogenic callus. Optimal embryogenic callus was induced from shoot apical meristem explants on Murashige and Skoog (MS) medium supplemented with 1mg/L 2,4-D. The addition of casein hydrolysate in the media increased the embryogenesis efficiency of sweetpotato. Somatic embryos were easily induced from the embryogenic callus on MS basal medium containing 300-500mg/L casein hydrolysate without phytohormon. Treatment of casein hydrolysate (100∼300mg/L) with 1mg/L 2,4-D also improved the secondary embryonic efficiency from somatic embryos below 2mm in length. Plant regeneration was achieved via somatic embryogenesis and direct organogenesis. Regenerated planlets with well developed shoots and roots on MS basal medium were successfully transferred to soil.

Increasing vitamin E activity in economically important oil crops such as soybean will enhance the nutritional value of these crops. An improved soybean transformation system involving pre-culture of soybean seed on medium supplemented with 1 mg/L 6-benzylaminopurine under dark conditions was established. To improve the nutritional value of soybean by increasing the α-tocopherol content, soybeans were transformed with γ-tocopherol methyltransferase (γ-TMT) gene by Agrobacterium-mediated transformation. Frequency of soybean transformation was significantly increased from 0.5 to 4.3% by this modified system, and 13 lines of transgenic soybean plants containing γ-TMT were obtained. The molecular characterization using polymerase chain reaction (PCR), reverse transcriptase PCR, and Southern blot analysis confirmed insertion and inheritance of the transgene in the transgenic plants and their progeny. Morphologically normal and fertile transgenic plants were analyzed, and the majority of transgenic soybean transmitted herbicide resistance at 3:1 or 15:1 ratios to their progeny. Alpha-tocopherol content in transgenic soybean seeds was determined by high-performance liquid chromatography; over-expression of γ-TMT resulted in a 41-fold increase in α-tocopherol over wild-type soybean seeds.

Flavonoids and carotenoids of pigmented rice ( Oryza sativa L.), including five black cultivars and two red cultivars, from Korea were characterized to determine the diversity among the phytochemicals and to analyze the relationships among their contents. Black cultivars were higher in flavonoids and carotenoids than the red and white cultivars. The profiles of eight phytochemicals identified from the rice grains were subjected to principal component analysis (PCA) to evaluate the differences among cultivars. PCA could fully distinguish between these cultivars. The Heugjinjubyeo (BR-1) and Heugseolbyeo (BR-2) cultivars were separated from the others based on flavonoid and carotenoid concentrations. Flavonoid contents had a positive correlation with carotenoid contents among all rice grains. The BR-1 and BR-2 cultivars appear to be good candidates for future breeding programs because they have simultaneously high flavonoid and carotenoid contents.

Estimation of the protein levels introduced in a biotechnology-derived product is conducted as part of an overall safety assessment. An enzyme-linked immunosorbent assay (ELISA) was used to analyze phosphinothricin acetyltransferase (PAT) and neomycin phosphotransferase II (NPT II) protein expression in a genetically modified (GM) pepper plant developed in Korea. PAT and NPT II expression levels, based on both dry weight and fresh weight, were variable among different plant generations and plant sections from isolated genetically modified organism (GMO) fields at four developmental stages. PAT expression was highest in leaves at anthesis (11.44 μg/gdw and 2.17 μg/gfw) and lowest in roots (0.12 μg/gdw and 0.01 μg/gfw). NPT II expression was also highest in leaves at anthesis (17.31 μg/gdw and 3.41 μg/gfw) and lowest in red pepper (0.65 μg/gdw and 0.12 μg/gfw). In pollen, PAT expression was 0.59-0.62 μg/gdw, while NPT II was not detected. Both PAT and NPT II showed a general pattern of decreased expression with progression of the growing season. As expected, PAT and NPT II protein expression was not detectable in control pepper plants.

To increase insect resistance in transgenic rice plants, a synthetic truncated cry1Ac gene was linked to the rice rbcS promoter and its transit peptide sequence (tp) for chloroplast-targeted expression. Several transgenic lines were generated by the Agrobacterium-mediated transformation method and the expression levels of the transgene were compared with untargeted expression. Use of the rbcS-tp sequence increased the cry1Ac transcript and protein levels by 25- and 100-fold, respectively, with the accumulated protein in chloroplasts comprising up to 2% of the total soluble proteins. The high level of cry1Ac expression resulted in high levels of plant resistance to three common rice pests, rice leaf folder, rice green caterpillar, and rice skipper, as evidenced by insect feeding assays. Transgenic plants were also evaluated for resistance to natural infestations by rice leaf folder under field conditions. Throughout the entire period of plant growth, the transgenic plants showed no symptoms of damage, whereas nontransgenic control plants were severely damaged by rice leaf folders. Our results demonstrate that the targeting of cry1Ac protein to the chloroplast using the rbcS:tp system confers a high level of plant protection to insects, thus providing an alternative strategy for crop insect management.

The quantitative trait loci (QTLs) for the dead leaf rate (DLR) and the dead seedling rate (DSR) at the different rice growing periods after transplanting under alkaline stress were identified using an F(2:3) population, which included 200 individuals and lines derived from a cross between two japonica rice cultivars Gaochan 106 and Changbai 9 with microsatellite markers. The DLR detected at 20 days to 62 days after transplanting under alkaline stress showed continuous normal or near normal distributions in F(3) lines, which was the quantitative trait controlled by multiple genes. The DSR showed a continuous distribution with 3 or 4 peaks and was the quantitative trait controlled by main and multiple genes when rice was grown for 62 days after transplanting under alkaline stress. Thirteen QTLs associated with DLR were detected at 20 days to 62 days after transplanting under alkaline stress. Among these, qDLR9-2 located in RM5786-RM160 on chromosome 9 was detected at 34 days, 41 days, 48 days, 55 days, and 62 days, respectively; qDLR4 located in RM3524-RM3866 on chromosome 4 was detected at 34 days, 41 days, and 48 days, respectively; qDLR7-1 located in RM3859-RM320 on chromosome 7 was detected at 20 days and 27 days; and qDLR6-2 in RM1340-RM5957 on chromosome 6 was detected at 55 days and 62 days, respectively. The alleles of both qDLR9-2 and qDLR4 were derived from alkaline sensitive parent "Gaochan106". The alleles of both qDLR7-1 and qDLR6-2 were from alkaline tolerant parent Changbai 9. These gene actions showed dominance and over dominance primarily. Six QTLs associated with DSR were detected at 62 days after transplanting under alkaline stress. Among these, qDSR6-2 and qDSR8 were located in RM1340-RM5957 on chromosome 6 and in RM3752-RM404 on chromosome 8, respectively, which were associated with DSR and accounted for 20.32% and 18.86% of the observed phenotypic variation, respectively; qDSR11-2 and qDSR11-3 were located in RM536-RM479 and RM2596-RM286 on chromosome 11, respectively, which were associated with DSR explaining 25.85% and 15.41% of the observed phenotypic variation, respectively. The marker flanking distances of these QTLs were quite far except that of qDSR6-2, which should be researched further.

By a differential cDNA screening technique, we have isolated a dehydration-inducible gene (designated OSRK1) that encodes a 41.8 kD protein kinase of SnRK2 family from Oryza sativa. The OSRK1 transcript level was undetectable in vegetative tissues, but significantly increased by hyperosmotic stress and Abscisic acid (ABA). To determine its biochemical properties, we expressed and isolated OSRK1 and its mutants as glutathione S-transferase fusion proteins in Escherichia coli. In vitro kinase assay showed that OSRK1 can phosphorylate itself and generic substrates as well. Interestingly, OSRK1 showed strong substrate preference for rice bZIP transcription factors and uncommon cofactor requirement for Mn(2+) over Mg(2+). By deletion of C-terminus 73 amino acids or mutations of Ser-158 and Thr-159 to aspartic acids (Asp) in the activation loop, the activity of OSRK1 was dramatically decreased. OSRK1 can transphosphorylate the inactive deletion protein. A rice family of abscisic acid-responsive element (ABRE) binding factor, OREB1 was phosphorylated in vitro by OSRK1 at multiple sites of different functional domains. MALDI-TOF analysis identified a phosphorylation site at Ser44 of OREB1 and mutation of the residue greatly decreased the substrate specificity for OSRK1. The recognition motif for OSRK1, RQSS is highly similar to the consensus substrate sequence of AMPK/SNF1 kinase family. We further showed that OSRK1 interacts with OREB1 in a yeast two-hybrid system and co-localized to nuclei by transient expression analysis of GFP-fused protein in onion epidermis. Finally, ectopic expression of OSRK1 in transgenic tobacco resulted in a reduced sensitivity to ABA in seed germination and root elongation. These findings suggest that OSRK1 is associated with ABA signaling, possibly through the phosphorylation of ABF family in vivo. The interaction between SnRK2 family kinases and ABF transcription factors may constitute an important part of cross-talk mechanism in the stress signaling networks in plants.