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Chromatin Interacting Factor OsVIL2 Is Required for Outgrowth of Axillary Buds in Rice
Gynheung An,Jinmi Yoon,조래현,이시철,Richa Pasriga,윈툰,Jungil Yang,Hyeryung Yoon,Hee Joong Jeong,전종성 한국분자세포생물학회 2019 Molecules and cells Vol.42 No.12
Shoot branching is an essential agronomic trait that impacts on plant architecture and yield. Shoot branching is determined by two independent steps: axillary meristem formation and axillary bud outgrowth. Although several genes and regulatory mechanism have been studied with respect to shoot branching, the roles of chromatin-remodeling factors in the developmental process have not been reported in rice. We previously identified a chromatin-remodeling factor OsVIL2 that controls the trimethylation of histone H3 lysine 27 (H3K27me3) at target genes. In this study, we report that loss-of-function mutants in OsVIL2 showed a phenotype of reduced tiller number in rice. The reduction was due to a defect in axillary bud (tiller) outgrowth rather than axillary meristem initiation. Analysis of the expression patterns of the tiller-related genes revealed that expression of OsTB1, which is a negative regulator of bud outgrowth, was increased in osvil2 mutants. Chromatin immunoprecipitation assays showed that OsVIL2 binds to the promoter region of OsTB1 chromatin in wild-type rice, but the binding was not observed in osvil2 mutants. Tiller number of double mutant osvil2 ostb1 was similar to that of ostb1, suggesting that osvil2 is epistatic to ostb1. These observations indicate that OsVIL2 suppresses OsTB1 expression by chromatin modification, thereby inducing bud outgrowth.
Roles of Sugars in Controlling Flowering Time
Gynheung An,전종성,조래현,Richa Pasriga,Jinmi Yoon 한국식물학회 2018 Journal of Plant Biology Vol.61 No.3
Flowering time is influenced by environmentalfactors such as photosynthesis, temperature, nutrition, andwater. The main products of photosynthesis are sugars thatare mobilized to sink tissues to support plant growth anddifferentiation. They also function as signals to controlvarious types of metabolism and developmental processes. One of the most important transitions in the plant life cycleis from the vegetative to reproductive phase. During thattransition, sucrose levels rise rapidly but transiently in thephloem and shoot apexes. For several species, the addition ofexogenous sucrose promotes flowering, possibly by acting asa main signal. Although other sugars, including glucose, alsoappear to be involved in this transition, evidence for theirroles in flowering is limited. In Arabidopsis thaliana,trehalose-6-phosphate serves as a signal to induce flowering. However, its roles in other plants have not been reported. Sucrose seems to function primarily in the leaf phloem toenhance the generation of florigens such as Flowering LocusT (FT) while trehalose-6-phosphate functions in the shootapical meristem to promote the flowering signal pathwaydownstream of those florigens.
Chromatin remodelling factors OsVIL2 and OsVIL4 control flowering time and yield in rice
Gynheung An 한국육종학회 2013 한국육종학회 심포지엄 Vol.2013 No.07
Flowering is exquisitely regulated by both promotive and inhibitory factors. Molecular genetic studies with Arabidopsis have verified several epigenetic repressors that regulate flowering time. However, the roles of chromatin remodeling factors in developmental processes have not been well explored in rice. We identified a chromatin remodeling factor OsVIL2 (O. sativa VIN3-LIKE 2) that promotes flowering. OsVIL2 contains a plant homeodomain (PHD) finger, which is a conserved motif of histone binding proteins. Insertion mutations in OsVIL2 caused late flowering under both long and short days. In osvil2 mutants OsLFL1 expression was increased, but that of Ehd1, Hd3a and RFT1 was reduced. We demonstrated that OsVIL2 is bound to native histone H3 in vitro. Chromatin immunoprecipitation analyses showed that OsVIL2 was directly associated with OsLFL1 chromatin. We also observed that H3K27me3 was significantly enriched by OsLFL1 chromatin in the wild type, but that this enrichment was diminished in the osvil2 mutants. These results indicated that OsVIL2 epigenetically represses OsLFL1 expression. We showed that OsVIL2 physically interacts with OsEMF2b, a component of polycomb repression complex 2. As observed from osvil2, a null mutation of OsEMF2b caused late flowering by increasing OsLFL1 expression and decreasing Ehd1 expression. Thus, we conclude that OsVIL2 functions together with PRC2 to induce flowering by repressing OsLFL1. Transgenic plants over-expressing OsVIL2 flowered early. In addition, they were taller and ticker due to increased in cell number, resulting in yield increase. The same phenotypes were observed from OsVIL4 knockout mutants. These indicate that OsVIL4 represses OsVIL2 function by directly binding to the protein.
Molecular Genetics Using T-DNA in Rice
An, Gynheung,Lee, Shinyoung,Kim, Sung-Hyun,Kim, Seong-Ryong Oxford University Press 2005 Plant & cell physiology Vol.46 No.1
<P>Now that sequencing of the rice genome is nearly completed, functional analysis of its large number of genes is the next challenge. Because rice is easy to transform, T-DNA has been used successfully to generate insertional mutant lines. Collectively, several laboratories throughout the world have established at least 200,000 T-DNA insertional lines. Some of those carry the <I>GUS</I> or <I>GFP</I> reporters for either gene or enhancer traps. Others are activation tagging lines for gain-of-function mutagenesis when T-DNA is inserted in the intergenic region. A forward genetic approach showed limited success because of somaclonal variations induced during tissue culture. To utilize these resources more efficiently, tagged lines have been produced for reverse genetics approaches. DNA pools of the T-DNA-tagged lines have been prepared for polymerase chain reaction (PCR) screening of insertional mutants in a given gene. Appropriate T-DNA insertion sites are determined by sequencing the region flanking the T-DNA. This information is then used to make databases that are shared with the scientific community. International efforts on seed amplification and maintenance are needed to exploit these valuable materials efficiently.</P>
A simple, rapid, and high-throughput DNA extraction method for PCR analysis from rice plants
Sung-Ryul Kim,Gynheung An,Kshirod K Jena 한국육종학회 2013 한국육종학회 심포지엄 Vol.2013 No.07
Polymerase chain reaction (PCR) is highly utilized for QTL analysis, positional cloning of valuable genes, and molecular breeding in crop science. Usually those experiments handle DNA samples of many genotypes (up to several thousands). However, many DNA extraction protocols require longer time using harmful chemicals such as chloroform, phenol, and liquid nitrogen. Here, we introduce a new DNA extraction method for PCR with agarose/PAGE analysis from a diversity panel of rice genotypes identified with yield enhancing traits. This protocol consists of four steps including injection of extraction buffer (20 mM Tris-HCl pH9.5, 200 mM KCl, 2 mM EDTA) into the tubes containing leaf tissues and steel balls, and crushing tissues using Geno-Grinder without liquid nitrogen, sample incubation at 65°C, and then centrifugation for removing cell debris. After centrifugation the crude extracts directly used as template DNA for PCR. Through this protocol we could complete F1 hybridity test from approximately 2,100 plants that come from 96 cross combinations with 13 SSR markers. In addition, we tested the DNA quality by PCR amplification of high GC-rich region and large target size (-2kb). From these results our DNA extraction method produces enough DNA quality for PCR and is suitable for large scale molecular analysis from rice plants.