Vitamin E and phytosterols are both valuable nutrients that act as antioxidants in human bodies. Understanding the genetic basis of these traits is necessary for the improvement of nutritional quality by breeding. In this study, 119 rice accessions of diverse origin were genotyped using 232 SSR markers to identify marker–trait associations with Vitamin E and phytosterols in rice. Analysis of population structure revealed four subgroups in the population. Linkage disequilibrium (LD) patterns and distributions are of fundamental importance for genome-wide mapping associations. The mean r2 value for all intra-chromosomal loci pairs was 0.3361. LD between linked markers decreased with distance. Marker–trait associations were investigated using the unified mixed-model approach, considering both population structure (Q) and kinship (K). In total, 81 marker–trait associations were identified using 232 different SSR markers covering 12 chromosomes. The results suggest that association mapping in rice is a viable alternative to quantitative trait loci mapping. The results from this association mapping study will be the basis for improving rice nutritional quality.
Inactivation of the gene (DFR-A) coding for dihydroflavonol 4-reductase (DFR) involved in the anthocyanin biosynthesis pathway results in a yellow bulb color in onion (Allium cepa L.) and three inactive alleles have previously been identified in onion. Additionally, three active and six inactive DFR-A alleles were newly identified from extensive analyses of diverse onion germplasm. Presently, a yellow mutant containing a 171-bp deletion in the promoter region was identified and designated DFR-APD. Critically reduced transcription of this mutant allele and perfect co-segregation with color phenotypes in segregating populations were observed. Another yellow mutant (DFR-A5’DEL) containing a 518-bp deletion covering exons 1 and 2, which played important roles in DFR function, was identified. Meanwhile, both 2-bp and 4-bp insertions in the coding region leading to creation of pre-mature stop codons were also identified and designated DFR-AGT and DFR-A2AT, respectively. A 1-bp substitution mutation (DFR-AK48N) changing a positively charged lysine residue into a neutral asparagine was identified. This lysine residue, a NADPH binding site, was strictly conserved in other species. In addition, insertion of a leucine residue around substrate binding sites and catalytic triad was identified in several yellow accessions and was designated DFR-ATTA. Phylogenetic analysis of DFR-A alleles showed that all inactive alleles were independently derived from four different active alleles. In addition, the close relatedness and diversity of DFR-A mutants implied that all these mutations might have occurred after domestication of onions and had probably been maintained by artificial selection.
Plants have evolved a set of protecting mechanisms against pathogens, which include secondary metabolites and induced defense responses to pathogen attack. The biological role of purine alkaloids including caffeine is largely unknown. It has been proposed that caffeine confers a resistance against pathogenic bacteria and herbivores. We, in this study, tested direct effects on the growth of rice pathogenic microbes, Xanthomonas oryzae pv. oryzae (Xoo) causing a bacterial leaf blight and Magnaporthe grisea (M. grisea) causing a rice blast. Cell growth of Xoo and M. grisea were significantly retarded in presence of high concentration (2mM) of caffeine. Exogenous caffeine (5mM) induced resistance of wild type rice (cv. Dongjin, susceptible to Xoo and M. grisea) against those pathogens. These results indicated that caffeine enhanced the basal resistance to infection with Xoo. In addition, expression of pathogenesis-related (PR) genes was tested in the caffeine treated rice to elucidate the acquired resistance by caffeine, resulted in induction of PR genes including OsPR1a and OsPrb1. We have generated a transgenic rice producing caffeine by introduction of three N- methyltransferase genes (CaXMT1, CaMXMT1, CaDXMT1) identified from coffee plant. The transgenic rice successfully expressed the three genes, synthesized caffeine up to 5ug/g and showed enhanced resistance to Xoo. We also observed that transcripts of PR genes such as the OsPR1a and OsPrb1 encoding PR-1 type pathogenesis-related protein increased in the caffeine-producing rice. These result showed that caffeine is likely to act a powerful factor to increase level of rice defense as a natural and non-harmful metabolite.
Soybean [Glycine max (L.) Merrill] is one of the world’s most major crops as not only an important source of oil and protein, but also secondary metabolites. Intake of soybean is associated with decreased risk of cardiovascular disease and osteoporosis, as well as cancer, including breast and colon cancers. Seventy soybeans germplasms collected from 4 different countries, America (6 varieties), China (15 varieties), Japan (16 varieties), and Korea (33 varieties), were distributed by Chungbuk National University (Cheongju, Chungbuk, Korea) and cultivated in Konkuk University farm. This study investigated the isoflavones in seventy soybeans according to 4 different origins (America, China, Japan and Korea). Between 4 different origins, Korea showed highest concentrations of total isoflavones (1292.6 ± 438.6 ㎍ g-1) and China showed the lowest concentrations of total isoflavones (843.8 ± 365.7 ㎍ g-1). The total isoflavone contents in soybean of America and China ranged from 572.3 ㎍ g-1 to 2001.9 ㎍ g-1 and from 275.8 ㎍ g-1 to 1521.8 ㎍ g-1, respectively. And the isoflavone contents of Japan and Korea ranged from 473.3 ㎍ g-1 to 2314.6 ㎍ g-1 and from 419.0 ㎍ g-1 to 3010.7 ㎍ g-1, respectively. Malonylgenistin (356.9 ± 158.8 ㎍ g-1) was the major isoflavones among 12 isoflavones. Specially, glycoside and malonylglycosides constituted 49.2 % and 45.3 % of total isoflavones in soybeans, respectively.
The early senescence mutant was isolated from the japonica rice Koshihikari through Ethyl-methane-sulfonate (EMS) mutagenesis. The early senescence phenotype was controlled by a single recessive gene, tentatively symbolized as es-k. Using an F2 population derived from a cross between the mutant and Milyang23 and molecular markers, we mapped the es-k locus to the long arm of chromosome 7 between STS markers 147-1 and 147-2 with a physical distance of 66-kb. The symptom of early senescence appeared even before heading, while appeared during ripening in wild-type. Physiological characteristics of the es-k mutant before initiation of senescence was similar to the wild-type. However, after heading, es-k mutants started to exhibit a significant decrease in chlorophyll and soluble protein content compared to the wild-type. The wild-type leaf color appeared normal irrespective of temperature treatment, while the leaf of es-k mutant appeared pale-green at the low temperature and dark-green at the high temperature. During dark-induced senescence, mutant did not show significant differences compared to normal type. The results show that es-k is sensitive to temperature but not to light.
Microsatellites are one of the most suitable markers for variety identification as it has great discrimination power for varieties with narrow genetic variation. The polymorphism level between forty microsatellite primer pairs and 148 soybean varieties was investigated through fluorescence based automatic detection system. A set of 16 primer pairs showed highly reproducible and polymorphic in these varieties. A total of 204 alleles were detected by using 16 microsatellite markers. The number of alleles per locus ranged from 6 to 28 with an average of 12.75 alleles per locus. The average polymorphism information content (PIC) was 0.86 ranging from 0.75 to 0.95. Two hundred four microsatellite loci were used to calculate Jaccard’s distance coefficients for unweighted pair group method using the arithmetic averages cluster analysis. These varieties were separated into several distinctive groups corresponding to varietal types. All of the varieties were perfectively discriminated by markers genotypes. This information may be useful to compare through genetic relationship analysis between existing and candidate varieties in distinctive tests and protection of plant breeders’ intellectual properties rights through variety identification.
The legume family is the third largest group, including approximately 650 genera and 18,000 species, in the flowering plants and the second important crops to the Poaceae in the agricultural economy. Comparative analysis is a useful tool to understand cross-species genomic structure and alterations during organism’s evolutionary history. In this study, we constructed a composite comparative map of ten legume species, including Medicago truncatula, Medicago sativa, Lens culinaris, Pisum sativum, Lotus japonicus, Cicer arietinum, Vicia faba L, Vigna radiata, Phaseolus vulgaris and Glycine max. Of these species, M. truncatula, which is a representative model system, played a central role to develop the cross-genome amplifiable PCR gene markers for the purpose of transferring them to other related legume species. A total of 108 cross-species core markers were employed to analyze genomic colinearity across this broad array of legume species. The comparative map demonstrates a diverse array of evolutionary events, such as duplications, inversions and reciprocal translocations. It is anticipated that resulting maps would provide a broader insights into the lineage-specific genomic organization of these glalegoid/phaseoloid legumes, which are two clades containing almost all crop legumes of economic importance, and can further used for the molecular breeding through translating genomic information into other orphan legumes.
Cross-species translation of genomic information may play a crucial role in applying biological knowledge gained from one species to other genomes. To screen and identify a broad range of abiotic stress-responsive genes, we employed a diverse array of resources, including Arabidopsis databases (http://www.arabidopsis.org), expression profiling data and previously reported literatures. As a result, a total of 1,377 genes were identified and classified into 18 different functional criteria based on biological processes of gene ontology. The gene set was translated into M. truncatula, which is a representative model system in the Fabaceae, by identifying orthologous genes between these two genomes with a combination of tBlastx and BlastP analyses. It is shown that approximately 82% of genes were estimated to be translated between the two genomes below the E-value of 10-30. These orthologous loci were used to construct comparative maps by developing a user-friendly analysis platform, resulting in a total of 52 synteny blocks. Furthermore, to discover central genes by which control responses to the abiotic stresses, a combination of AraNet (http://www.functionanet.org) and the Cytoscape program was used for the gene network analysis. The analysis resulted in the identification of 240 potential key genes. We anticipate that these genes may impact molecular breeding programs by discovering trait-associated SNPs followed by marker development.
Copy number variations (CNVs) are considered major sources of genetic variation, and CNVs may influence phenotypic variation and gene expression. To detect CNVs, rice seeds were exposed with 100~400 Gy of gamma-ray (GA, 60Co), cosmic-ray (CR) by Russia ISS, and 30 and 40 Gy of ion beam (IB, 220 Mev carbon ion). After the exposed rice seeds were cultured in 1/2 MS medium for 14 days, they were used for array-based Comparative genomic hybridization (CGH) analysis using Agilent’s RICE CGH array. As a results, the highest number of CNVs (Gain 808 and Loss 24,080) were detected in the CR treatment, whereas GA100 (100 Gy of GA) was identified the least CNVs. Compared individual chromosome, the chromosome 8 and 11 were identified the highest CNVs, the chromosome 3 had the least CNVs. Most of identified CNVs existed in the range of 10~500kb. In particular, the same CNV locations among different types of ionizing radiation were observed in chromosome 12, and these CNVs contained the commonly 5 amplified genes, containing retrotransposon protein, NADH-ubiquinone oxidoreductase chain 3, heavy metal transport/detoxification protein domain containing protein, and 2 unknown proteins. Other studies were reported that Ty1 (Long Terminal Repeat-retrotransposon family 1) transcription and retrotransposition were induced by different environmental stresses such as ionizing radiation, UV-light exposure, DNA damage and nutrient starvation in Saccharomyces cerevisiae. Our results also show that retrotransposon protein (LOC_Os12g34016) was specifically amplified by different types of ionizing radiation.
Small RNAs including microRNAs (miRNAs) and small interfering RNAs (siRNAs) play crucial roles in post-transcriptional gene silencing (PTGS) in eukaryotes. Small RNAs function cell-autonomously as well as non-cell-autonomously. It has been well characterized that pathogenic fungi secrete some effector molecules, which facilitate their infection into plants. However, it is not clear whether molecules in plant cells are able to move into fungal cells during infection. To test if small RNAs generated from plant cells can also move to fungal cells during infection, we generated transgenic Arabidopsis and rice plants ectopically expressing either double-stranded RNA interference (dsRNAi) or artificial miRNA (amiRNA) constructs targeting GFP gene. And then these transgenic plants were inoculated with transgenic rice blast fungus, Magnaporthe oryzae, expressing GFP transgene. Here, we showed that ectopic expression of both dsRNAi and amiRNA targeting GFP gene in transgenic plants significantly suppressed GFP expression in rice blast fungi inoculated, indicating that small RNA molecules generated in plant cells can move into infected fungal cells and efficiently degrade fungal GFP transcripts. Our results would provide a new small RNA-based strategy for the development of resistant crops against fungal pathogens.
Comparative analysis is a typically useful tool for translating genomic information from one species to another. However, currently available softwares are relatively difficult to directly use for researchers that are not familiar with use of bioinformatic tools. Therefore, we intended to develop a new platforms and/or interface through which one can use in more comfortable way, based on the concept of interactive comparative analysis. Towards this direction, we, firstly, constructed relational database to store the information on abiotic stress genes identified from multiple plant species using various resources, such as the TAIR (http://www.arabidopsis.org), gene expression profiles and relevant literatures, and linked with comparative analysis interface. For purposes of comparative analysis and identification of synteny blocks, cross-species orthologous genes were determined using a combination of tBlastX and BlastP homology searches. We adapted and developed a Circos-like format to present resulting comparative maps. Users can readily choose analysis parameters, for example individual genes and specific chromosomes for chosen species, in the pane of analysis DB, which is useful feature to avoid complexity of comparative genomic analysis. This DB-associated comparative analysis tool, developed in this study, will be able to provide customer-friendly interface for comparative analysis and extend its utility across a broader range of plant genomes.
Aroma development in rice has been reported due to the lack of function of betaine aldehyde dehydrogenase gene (badh2) on rice chromosome 8. A lot of functional markers have been designed based on the InDels, such as 7bp deletion in exon 2, 803bp deletion in exon 4 and 5, 8bp deletion in exon 7, and 3bp insertion in exon 13. Although there were a lot of functional SNPs, other InDels have not been detected by a PCR-based marker. Here we developed a simple, co-dominant, functional cleaved amplified polymorphic sequence (CAPS) marker for fragrance trait based on 1bp insertion in exon 14. The developed marker showed a high efficiency in discriminating that special aromatic rice variety, and displayed perfect co-segregation with the trait of fragrance in the F2 population. This new marker developed in the present study would be useful in molecular breeding of fragrant rice varieties.
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.
NGS costs are decreasing rapidly, and beneficial application of the technology to plant genomics seems inevitable. Trying to interpret the agriculturally important traits like yield is actively in progress all across the globe. However, the current stage of bio-informatic technology as applied to the interpretation of agricultural trait appears not yet at a level of maturity to justify widespread plant genome sequencing for user-friendly molecular breeding. It is necessary to construct dense mutation block (DMB) based molecular breeding system for selecting plants with optimal agricultural performance; as well as for identifying useful quantitative trait loci (QTLs).
Firstly, we screened and selected DMBs-specific INDEL markers obtained from SNV density profiles using 42 genome sequences of Korean cultivar and public sequences of 24 japonica rice cultivars. Secondly, we analyzed the genetic similarity between 288 Korean cultivars using 113 DMB-specific INDEL markers, which could differentiate on agarose gel by PCR. And we are going to integrate 360 INDEL markers up to 30 per each chromosome. Finally, we selected 40 founder lines considering the importance of the breeding, the purpose of use, and plant ecotype. To construct rice nested association mapping population we crossed each founder lines with the pollen of Hwayoungbyeo which was most commonly used in korean rice breeding program. F2 seed multiplication and generation iteration are ongoing.
The precise, fast, and cost-effective identification of important fruit crop cultivars is essential for practical breeding and plant breeder’s rights. Traditional methods for identification of persimmon cultivars are based on the evaluation of sets of morphological characteristics. However, the identification using only morphological traits is difficult to distinguish among genetically closely related cultivars. This study was conducted to develop more reliable DNA markers for identification of the 32 persimmon cultivars in Korea and Japan. In total, 309 random amplified polymorphic DNA (RAPD) markers were identified using 40 different random primers. The 4 (OPP-08) to 14 (UBD159) polymorphic bands were detected with an average of 7.7. The resulting 57 RAPD fragments were selected, and their sequences were determined for developing sequence-characterized amplified region (SCAR) markers. As a result, 15 of 57 RAPD fragments were successfully converted to SCAR markers. A single polymorphic band of the same size as the RAPD fragments or smaller DNA fragments were amplified depending on primer combinations in the 15 SCAR markers. Among these markers, a combination of eight SCAR markers (PS225_200, PSN05_420, PSF13_523, PSN11_540, PS372_567, PS485_569, PSP08_635, and PS631_735) provided sufficient polymorphisms to identify 32 persimmon cultivars depending on number and size of amplicons. These newly developed markers will be useful as a fast and reliable tool to identify persimmon cultivars.
The ubiquitin conjugating enzyme E2 (UBC E2) mediates selective ubiquitination, acting with E1 and E3 enzymes to designate specific proteins for subsequent degradation. In the present study, we characterized the function of the mung bean VrUBC1 gene (Vigna radiata UBC 1). RNA gel-blot analysis showed that VrUBC1 mRNA expression was induced by either dehydration, high salinity or by the exogenous abscisic acid (ABA), but not by low temperature or wounding. Biochemical studies of VrUBC1 recombinant protein and complementation of yeast ubc4/5 by VrUBC1 revealed that VrUBC1 encodes a functional UBC E2. To understand the function of this gene in development and plant responses to osmotic stresses, we overexpressed VrUBC1 in Arabidopsis (Arabidopsis thaliana). The VrUBC1-overexpressing plants displayed highly sensitive responses to ABA and osmotic stress during germination, enhanced ABA- or salt-induced stomatal closing, and increased drought stress tolerance. The expression levels of a number of key ABA signaling genes were increased in VrUBC1-overexpressing plants compared to the wild-type plants. Yeast two-hybrid and bimolecular fluorescence complementation demonstrated that VrUBC1 interacts with AtVBP1 (A. thaliana VrUBC1 Binding Partner 1), a C3HC4-type RING E3 ligase. Overall, these results demonstrate that VrUBC1 plays a positive role in osmotic stress tolerance through transcriptional regulation of ABA-related genes and possibly through interaction with a novel RING E3 ligase.
Soybean is an important crop with useful traits such as the high seed protein and oil contents. Soybean reproduction is sensitive to temperature over 35℃. To obtain database of gene expression profiles, we used soybean cultivars, sensitive and tolerant. RNA sequencing was performed to find differentially expressed genes in two Korean soybean cultivars under heat stress condition. The transcriptomic changes in each cultivar under heat stress. We found 2727 common transcripts in two soybean cultivars under heat stress, and selected 20 transcripts to heat stress response genes. The 20 selected genes were analysed using BLAST2GO and PLANEX. The genes were major factor in co-expression networks. It appears that these 20 genes were mainly attributable to heat stress.
Doubled haploid system is a very effective tool which has been widely applied in wheat breeding programmes. Wide-hybridization, wheat X maize cross, is used for the production of wheat doubled haploids (DH). The introduction of doubled haploid (DH) approach into breeding programs has reduced the times and population sizes required for the production of pure lines. We carried out the experiment for development on effective method of producing haploid in wheat. Emasculated spikelets of wheat were pollinated with maize pollen and cultured in the solution containing 40 g/ℓ sucrose and 2,4-D, ABA and GA3 24 h after pollination, and then incubated until embryo rescue. twelve to fourteen days after pollination, the embryos are excised and cultured in half-strength MS basal medium supplemented with 20 g/ℓ sucrose and 1 ㎎/ℓ NAA. The type of plant growth regulators was found to be most significant in production of haploid plants. The application of synthetic auxins to pollinated florets, stimulates haploid embryo development to a stage where the embryos can be rescued onto nutrient media. The percentage of embryos formed was significantly affected by 100 ㎎/ℓ 2,4-D plus 50 ㎎/ℓ BAP and 100 ㎎/ℓ 2,4-D plus 50 ㎎/ℓ GA3. There was varied efficiency in embryo formation from 5.7 to 53%.
Genome duplication is an abundance phenomenon and in plant kingdom and consequently formed paralogous region. Korean ginseng (Panax ginseng C.A. Meyer) has a possibility of tetraploid by comparing chromosome numbers of relative species. During development of EST-SSR markers in Korean ginseng, most of primer sets have produced multiple bands in gel electrophoresis. In this study, for identifying origin of multiple bands, five EST-SSR markers showing multi-band were selected and two bands around expected size were sequenced. Sequence comparison classified the multiple bands into individual loci. Two bands can be identified by SNP or InDel variation with number of SSR units. Sequencing result represented that paralogous loci with high similarity were existence caused by recent duplication. One clear band were amplified with newly designed locus specific primer picked from SNP variation. SNP and InDel polymorphism between paralgous loci were useful for identifying each locus. This study will provide better understanding of ginseng genome and will be helpful for development of DNA markers.
Recent global warming and climate change has presented greater challenge to the global agriculture of having to cope with more severe adversaries from various abiotic stress conditions including drought, cold, and heat. As a preliminary step towards developing a heat-tolerant japonica rice variety through molecular breeding, we examined and compared expression of several genes that have been reported being expressed specifically during rice panicle development in different rice varieties after subjecting them heat stress. Although the induction of these transcripts upon heat treatment was invariably observed in all rice varieties tested, the magnitude and kinetics of the induction were found to be different among these varieties, suggesting possible functional implication of these genes in conferring heat tolerant phenotype during reproductive organ development of these plants. General protein synthesis activity as well as pollen viability incurred by the heat stress treatment were also monitored in these plants and the result showed a close correlation overall with the induction dynamic of these transcripts under heat stress. Therefore, these genes, together with the ones involved in the regulatory network for the expression of them, could serve as candidates for useful markers with which molecular breeding of heat tolerant japonica rice can be facilitated.