The plant-specific NAC transcription factors control various biological processes, including plant development and stress responses. We have isolated an ANAC032 gene, one of the NAC transcription factor family, which was highly activated by multi-abiotic stresses, including high salt and drought in Arabidopsis. Here, we generated transgenic plants constitutively expressing ANAC032 and its knockout to identify the functional roles of ANAC032 in Arabidopsis under abiotic stress responses. The ANAC032-overexpressing plants showed enhanced tolerance to salinity and drought stresses. The anac032 knockout mutants were observed no significant changes under the high salt and drought conditions. We also monitored the expression of high salt and drought stress-responsive genes in the ANAC032 transgenic plants and anac032 mutant. The ANAC032 overexpression upregulated the expression of stress-responsive genes, RD29A and ERD10, under the stresses. Thus, our data identify that transcription factor ANAC032 plays as an enhancer for salinity and drought tolerance through the upregulation of stress-responsive genes and provides useful genetic traits for generating multi-abiotic stress-tolerant forage crops.

Microalgae are a group of photosynthetic microorganisms living in the water. They are in the spotlight as biostimulators and biofertilizers in modern renewable and sustainable agriculture system, attributed to characteristics such as photosynthetic, and metabolism of various industrial wastes and to increase production when treating crops. Scenedesmus sp. CHK0059 is also one of the microalgae with these characteristics, and it has been reported to suppress various diseases in crops and promote the health of vegetables. However, the mode of action that has a positive effect on plants is not yet well understood. This study was designed to focus on the modulation in diversity change of plant microbiota community, which was the result of the preliminary study, and to determine the direct changes in microbial members that trigger the diversity change in the Arabidopsis model system. As a result, there was no change in the phenotype of Arabidopsis and the microbiota community structure in the rhizosphere during the treatment period, but two bacteria genera, Brevibacterium and Pseudomonas, dominance in the rhizosphere was positively correlated with the CHK0059 treatments. And the bacteria had a positive network correlative relationship with 24 other bacteria. Our findings suggest that the application of microalgae was correlated with several microbiota members in the rhizosphere and was expected to affect the microbiota community structure modification in long-term treatment.

본 연구는 식물검역 분야에서 주요하게 사용되고 있는 메틸브로마이드 훈증제로 인해 발생하는 약해를 저감하기 위한 물질을 모델식물인 애기장대를 이용하여 스크리닝하였다. 사전연구를 통하여 메틸브로마이드 훈증제의 식물 독성 메커니즘으로 활성산소발생와 식물 성장 호르몬인 옥신의 식물체 내 분배억제효과가 발생하는 것을 바탕으로 하여, 약해 저감물질후보군으로 활성산소를 제거하는 역할을 하는 ROS scavenger 2종 (NAC, GSH)과 옥신을 훈증제 처리 전 애기장대에 처리한 후 약해의 저감 정도를 육안평가와 더불어 관련 유전자의 발현을 확인하였다. 연구 결과 메틸브로마이드에 의해 유도된 약해는 옥신보다는 활성산소를 저감시키는 물질후보군들에서 약해 저감효과가 나타났다. 이 중 GSH을 이용하여 농도구배하여 전처리하였을 때, 5 mM GSH 전처리 후 메틸브로마이드 훈증 시 약해 저감효과가 두드러졌다. GSH 전처리 시 식물체 내에 MBF1c와 HSP70 유전자 발현이 증가하는 것을 확인하였으며, 이는 메틸브로마이드 훈증으로 유도되는 약해를 방어하는 역할을 담당하였을 것이라고 평가된다. 따라서, 식물검역 훈증제 메틸브로마이드에 의해 발생하는 약해를 저감하는 데 GSH의 사용가능성을 평가하였으며, 이를 기반으로 다양한 식물체에 적용하여 수출입 시 약해로 인한 경제적 손실을 감소시킬 수 있기를 기대한다.

Arabidopsis nucleoside diphosphate kinase 2 (AtNDPK2) is an upstream signaling molecule that has been shown to induce stress tolerance in plants. In this study, the AtNDPK2 gene, under the control of a stress-inducible SWPA2 promoter, was introduced into the genome of tall fescue (Festuca arundinacea Schreb.) plants. The induction of the transgene expression mediated by methyl viologen (MV) and NaCl treatments were confirmed by RT-PCR and northern blot analysis, respectively. Under salt stress treatment, the transgenic tall fescue plants (SN) exhibited lower level of H2O2 and lipid peroxidation accumulations than the non-transgenic (NT) plants. The transgenic tall fescue plants also showed higher level of NDPK enzyme activity compared to NT plants. The SN plants were survived at 300 mM NaCl treatment, whereas the NT plants were severely affected. These results indicate that stress-inducible overexpression of AtNDPK2 might efficiently confer the salt stress tolerance in tall fescue plants.

Recently, RNA interference (RNAi) technology has been emerged as a potent tool for pest control strategy. Based on the previous studies on RNAi via leaf disc-mediated systemic delivery of dsRNA and in planta expression of hairpin RNA by agroinfiltration, the coatomer subunit alpha (COPA) gene has been found to be a crucial target for RNAi against Tetranychus urticae. In current study, transgenic plants of Arabidopsis thaliana expressing COPA hairpin RNA were generated by the floral dip method. Putative transgenic plants were screened by PCR and positive transformants were subjected to bioassay using age-synchronized and host-adapted T. urticae. T. urticae feeding on plants expressing dsRNA/siRNA showed more than 80% mortality as compared to the mites feeding on control plants at 6 days post-infestation. Our data shows that in planta expression of hairpin gene such as COPA may serve as an effective way for the control of this important pest in ornamental and economically important plants.

Reactive oxygen and nitrogen species (ROS and RNS, respectively) are messengers that carry signals to alter the redox state in order to activate plant responses and other physiological processes, such as differentiation, aging, senescence, and pathogen defense. Quite a large number of genes are involved in this signaling and lead to oxidative stress in plants. Although the role of ROS/RNS during stress conditions is well documented, a comprehensive list of genes and comparative study of these genes has not yet been completed. Accordingly, the in silico identification of oxidative stress-related genes was performed for soybeans and Arabidopsis. These genes were also studied in relation to multiple domain prediction. The presence of domains like dehydogenase and ATPase suggests that these genes are involved in various metabolic processes, as well as the transportation of ions under optimal environmental conditions. In addition to a sequence analysis, a phylogenetic analysis was also performed to identify orthologous pairs among the soybean and Arabidopsis oxidative stress-related genes based on neighbor joining. This study was also conducted with the objective of further understanding the complex molecular signaling mechanism in plants under various stress conditions.

AtSAGT1 encodes a salicylic acid (SA) glucosyltransferase enzyme that catalyzes the formation of SA glucoside and SA glucose ester. Here, the AtSAGT1 gene expression patterns were determined in AtSAGT1 promoter::GUS transgenic Arabidopsis plants. As a result, the factors regulating the induction of AtSAGT1 were identified as pathogen defense response, wound response, exogenous application of SA, and jasmonic acid treatment.

As a preceding study for investigating the influence of sound wave stimulus on Arabidopsis thaliana metabolomics, the polar secondary metabolomes of the plant were determined using high performance liquid chromatography coupled with tandem mass spectrometry. A total of 10 polar secondary metabolomes were characterized and quantified. Among them, 4 metabolomes, p-coumaroylagmatine isomer (7 and 8), p-coumaroylagmatine isomer (9 and 10) were identified in the plant for the first time. The validation was conducted in terms of linearity, recovery, precision, limit of detection (LOD) and limit of quantification (LOQ). The validated method was applied to the simultaneous quantification of the 10 polar secondary metabolomes.

We identified cdf based on screening of the Arabidopsis cDNA library for functional suppressors of the AtBI-1 (a gene described to suppress the cell death induced by Bax gene expression in yeast). The cdf was located on Chr. V and was composed of 5 exons and 4 introns. It encodes a protein of 258 amino acid residues with a molecular weight of 28.8 kDa. The protein has 3 transmembrane domains in the C-terminal region. The cdf has one homologue, named cdf2, which was found in Arabidopsis. Like cdf, cdf2 also induced growth defect in yeast. The effect of the cell growth defect factor was somewhat lower than Bax. cdf could arrest the growth of yeast. Its localization to the nucleus was essential for the suppression of yeast cell proliferation. Morphological abnormality of intracellular network, which is a hallmark of AtBI-1, was attenuated by expression of cdf.

Inhibitory effect of colchicine on growth and gravitropic responses in Arabidopsis root was explored to find whether there was an involvement of ethylene production. It has been known that cytoskeleton components are implicated in sedimentation of statoliths to respond to gravitropism and growth. The root growth was inhibited by 25% and 40% over control for 8 hr treatment of colchicine at a concentration of 10-5 M and 10-7 M, respectively. The roots treated with colchicine at the concentration of 10-7 M showed the same pattern as control in 3 hr, however, gravitropic response was decreased in the next 5 hr. The colchicine treatment at the concentration of 10-5 M inhibited the gravitropic response resulting in 60° of curvature. In order to better understand the role of colchicine, the production of ethylene was measured with and without the treatment of colchicine. Colchicine increased the ethylene production by 20% when compared to control via the activation of ACC oxidase and ACC synthase activity. These results suggest that the inhibition of the growth and gravitropic responses of Arabidopsis roots by the treatment of colchicine could be attributed to the rearrangement of microtubule, and increase of ethylene production.

Background : Glycosylation of natural compounds results in great diversity of secondary metabolites. Glycosylation steps are implicated not only in plants growth and development but also in plant defense responses to various environmental stresses. This process is mediated by members of a multigene superfamily glycosyltransferase (GT), which catalyze the transfer of single or multiple activated sugars to a wide range of substrates, thus influences their chemical property and bioactivity. Although its activity has been recognized for a long time and genes coding UGTs in several higher plants have been identified, specific function of GTs in detail still remains elusive. Methods and Results : Spatial and temporal expression patterns of a ginseng UDP-dependent glycosyltransferase, was analyzed by qRT-PCR. It was expressed highly in rhizome, upper root and youngest leaf compared that of other organs. Spacial expression was observed by GUS histochemical assay after generating promoter::GUS fusion. Noticeably, it expressed axillary branch as well as other organs tested by qRT-PCR. Overexpression of PgUGT in Arabidopsis resulted in fused organ in axillary branch. Stress responsiveness against various abiotic stresses and subcellular localization in Arabidopsis are also addressed. Conclusion : PgUGT phylogenetically closed to PgUGT71A27 involved in ginsenoside compound K (C-K) production. Considering that the C-K is not reported in raw ginseng material, further characterization of this gene may shed light on the biological function of C-K in ginseng growth and development. Organ fusion phenotype could be caused by defective growth of cells in boundary region, commonly regulated by phytohormones such as auxins or brassinosteroids, which in needs to be analyzed further.

Seed germination is a key developmental transition that initiates the plant life cycle. The timing of germination is determined by coordinated action of two phytohormones, gibberellin (GA) and abscisic acid (ABA). In particular, ABA plays a key role in integrating environmental information and inhibiting the germination process. Utilization of embryonic lipid reserves contributes to seed germination by acting as an energy source, and ABA suppresses lipid degradation to modulate the germination process. Here, we report that the ABA-responsive R2R3-type MYB transcription factor MYB96, which is highly expressed in embryo, regulates seed germination by controlling the expression of ABA-INSENSITIVE 4 (ABI4). In the presence of ABA, germination was accelerated in MYB96-deficient myb96-1 seeds, whereas the process was significantly delayed in MYB96-overexpressing activation-tagging myb96-ox seeds. Consistently, myb96-1 seeds degraded a larger extent of lipid reserves even in the presence of ABA, while reduced lipid mobilization was observed in myb96-ox seeds. MYB96 directly regulates ABI4, which acts as a repressor of lipid breakdown, to define its spatial and temporal expression. Genetic analysis further demonstrated that ABI4 is epistatic to MYB96 in the control of seed germination. Taken together, the MYB96-ABI4 module regulates lipid mobilization specifically in the embryo to ensure proper seed germination under suboptimal conditions.

The circadian clock control of CONSTANS (CO) transcription and the light regulation of CO stability coordinately regulate photoperiodic flowering by triggering rhythmic expression of the floral integrator FLOWERING LOCUS T (FT). The diurnal pattern of CO accumulation is modulated sequentially by distinct E3 ubiquitin ligases, such as HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENES 1 (HOS1) in the morning, FLAVIN-BINDING, KELCH REPEAT, F-BOX 1 (FKF1) in late afternoon, and CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) at night. In particular, CO is stabilized by FKF1 in late afternoon only under long days. Here, we show that CO abundance is not simply regulated by the E3 enzymes in a passive manner but also self-regulated actively through dynamic interactions between two CO isoforms. CO alternative splicing produces two protein variants, the full-size COa and the C-terminally truncated COb. Notably, COb, which is resistant to the E3 enzymes, induces the interactions of COa with CO-destabilizing HOS1 and COP1 but inhibits the association of COa with CO-stabilizing FKF1. These observations demonstrate that CO plays an active role in sustaining its diurnal accumulation dynamics in Arabidopsis photoperiodic flowering.

The wild relatives of soybean [Glycine soja Sieb. and Zucc.] have curly/wavy nature whereas cultivated varieties are upright. Such morphological characteristics have agronomic importance too. To investigate the molecular mechanism of development contributing to coiled morphology, screening was carried out to look for Arabidopsis mutants in activation tagging lines obtained by activation T-DNA treatment that have curly/wavy morphology. A mutant named Coiled Branch 1 (cbr1), is found to have a wavy and curly morphology with coiling branches. Plasmid rescue and genomic southern blot analysis revealed the site of T-DNA insertion in the genome. RT-PCR was performed to monitor expression levels of the genes adjacent to the T-DNA integration sites, and showed the activation of an E3 ubiquitin ligase gene. Database search showed that the gene with the RING domain belongs to a family of E3 ubiquitin ligases. Complementation test by overexpression and RNA interference of the gene was also carried out. The complementation test results showed that the novel gene activation tagging affected the cbr1 mutant phenotypes. Ubiquitylation has been linked virtually to every cellular process including plant development. E3 ubiquitin ligase has been reported to recognize target proteins that are to be ubiquinated for further degradation by the proteasome complex. Further, more detailed studies are needed to identify the specific substrate(s) of the novel E3 ubiquitin ligase gene.

Acyl-acyl carrier protein (ACP) thioesterase (TE) catalyze the hydrolysis of the thioester bond that links the acyl chain to the sulfhydryl group of the phosphopantetheine prosthetic group of ACP. This reaction terminates acyl chain elongation of fatty acid biosynthesis, and in plant seeds it is the biochemical determinant of the fatty acid compositions of storage lipids. A full-length cDNA of an acyl-ACP thioesterase, named CvFatB, was isolated from oil plant Cuphea viscosissima accumulating up to 90% caprylate (8:0) and caprate (10:0) in its seed oil. This cDNA contains a 1,245-bp open reading frame that encodes a protein of 415 amino acids. The deduced sequence also contains two essential residues (H317 and C352) for TE catalytic activity and a putative chloroplast transit peptide at the N-terminal. Overexpression of the CvFatB cDNA in Arabidopsis resulted in increased levels of saturated fatty acid, especially palmitate, and reduced levels of unsaturated fatty acids. The findings suggest that CvFatB from oil plant C. viscosissima can function as a saturated acyl-ACP TE and can potentially be used to diversify the fatty acid biosynthesis pathway to produce novel fatty acids.