HAL1 mediate salt adaptation in Arabidopsis thaliana

The yeast HAL1 gene was introduced into Arabidopsis thaliana by Agrobacterium tumefaciens-mediated transformation with vacuum infiltration under the control of CaMV 35S promoter. Thirty-three individual kanamycin resistant plants were obtained from 75,000 seeds. Southern blotting analysis indicated that HAL1 gene had been integrated into all of the transgenic plants’ genomes. The copy number of HAL1 gene in transgenic plants was mostly 1 to 3 by Southern analysis. Phenotypes of transgenic plants have no differences with wild type plants. several samples of transformants were self-pollinated, and progenies from transformed and non-transformed plants (controls) were evaluated for salt tolerance and gene expression. Measurement of concentrations of intracellular K+ and Na+ showed that transgenic lines were able to retain less Na+ than that of the control under salt stress. Results from different tests indicated the expression of HAL1 gene promotes a higher level of salt tolerance in vivo in the transgenic Arabidopsis plants.

The NAC Transcription Factor ANAC089 Modulates Seed Vigor through the ABI5-VTC2 Module in Arabidopsis thaliana

Seed viability is an essential feature for genetic resource conservation as well as sustainable crop production.Long-term storage induces seed viability deterioration or seed aging,accompanied by the accumulation of toxic reactive oxygen species(ROS)to suppress seed germination.Controlled deterioration treatment(CDT)is a gen-eral approach for mimicking seed aging.The transcription factor ANAC089 was previously reported to modulate seed primary germination.In this study,we evaluated the ability of ANAC089 to control seed viability during aging.Compared with that in the wild-type line,the mutation of ANAC089 significantly increased H_(2)O_(2),thereby reducing seed viability after CDT,while the overexpression of ANAC089 reduced H_(2)O_(2) and improved seed long-evity,indicating a critical role for ANAC089 in maintaining seed viability through H_(2)O_(2) signaling.A series of stu-dies have shown that ANAC089 targets and negatively regulates the level of ABI5,an important transmitter of abscisic acid(ABA)signals,to affect seed viability after CDT.Furthermore,ABI5 negatively regulated the expres-sion of VTC2,which is involved in the biosynthesis of the antioxidant ascorbic acid and H_(2)O_(2) scavenging.As a result,ANAC089 attenuates the generation of H_(2)O_(2),thereby enhancing seed viability through the ABI5-VTC2 module during the seed aging process.Taken together,our results reveal a novel mechanism by which ANAC089 enhances seed viability by coordinating ABI5 and VTC2 expression,ultimately preventing the overac-cumulation of H_(2)O_(2),which would have led to reduced seed viability.

Dissecting Multiple Arabidopsis CC-NBS-LRR Proteins Structure and Localization

NBS-LRR (nucleotide binding sites and leucine rich repeat) protein plays a crucial role as sentries and as defense activators in plants. The structure and function of NBS-LRR proteins are closely related. Previous articles have announced that the activated ZAR1 (HopZ-Activated Resistance 1) forms a pentamer in the plasma membrane, which is a calcium permeable channel that can trigger plant immune signaling and cell death. However, the structure of galore NBS-LRRs in Arabidopsis is not yet clear. The functional sites of distinct NBS-LRR in cells may vary. In addition, identifying pathogens and activating defense regions may occur in different subcellular compartments. Therefore, dissecting the specific structure and positioning of NBS-LRRs is an indispensable step in understanding their functions. In this article, we exploit AlphaFold to predict the structure of some designed NBS-LRRs, and utilize Agroinfiltration transient expression system, combined with biochemical fractionation, to dissect the localization of these NBS-LRR receptors from Arabidopsis. Structural data indicates that the identified NBS-LRRs share analogous conformation. Membrane fractionation assay demonstrates these NBS-LRRs are mainly associated with the membrane. These data show that the Ca2+-permeable channel activity may be evolutionarily conserved in NBS-LRR of Arabidopsis, and this study provides some reference clues for analyzing the structure and localization patterns of other plant immune receptors.

Expression Pattern, Interaction Network, and Functional Analysis of the Arabidopsis Botrytis Susceptible1 Interactor

E3 ubiquitin ligases are participated in numerous processes, regulating the response to biotic and abiotic stresses. Botrytis susceptible1 interactor (BOI) is a RING (Really Interesting New Gene)-type E3 ligase that mediates the ubiquitination of BOS1 (Botrytis susceptible1), a transcription factor involved in stress and pathogen responses. Although BOI is an E3 ligase, there are reports to show that BOI interacts with target proteins such as DELLAs or CONSTANS to repress gibberellin responses and flowering without the degradation of the target proteins. In this article, we utilize diversified methods to comprehensively analyze the expression pattern, interaction network and function of BOI gene. Firstly, 1800 bp upstream region of BOI gene from Arabidopsis thaliana (Arabidopsis) genome was isolated, and fused GUS reporter gene. The resulting expression cassette was introduced into wild-type Arabidopsis through Agrobacterium-mediated transformation. The result demonstrated that BOI gene was expressed predominantly in leaves, siliques, young roots, and flowering tissues, indicating that BOI gene may be involved in multiple processes in plant growth and development in Arabidopsis. Besides, eight candidate interacting proteins were obtained from the Arabidopsis cDNA library via yeast two-hybrid technology, including EXO70E2 (AT5G61010), WRKY7 (AT4G24240), WRKY11 (AT4G31550), WRKY17 (AT2G24570), UBP20 (AT4G17895), L5 (AT1G12290), SAUR9 (AT4G36110) and TCP21 (AT5G08330). Functional analysis of these candidate interacting proteins manifested that they related to multiple pathways, including biological and abiotic stress, programmed cell death, protein degradation, material metabolism and transcriptional regulation. In addition, the results of the transient assay proclaimed that BOI protein affects the protein stability of EXO70E2 and L5 through its E3 ubiquitin ligase activity. Our results provide novel clues for a better understanding of molecular mechanisms underlying BOI-mediated regulations.

Overexpression of aspen sucrose synthase gene promotes growth and development of transgenic Arabidopsis plants

In plants, sucrose synthase (SUS) enzymes catalyze conversion of sucrose into fructose and UDP-glucose in the presence of UDP. To investigate the impact of overexpression of heterologous SUS on the growth and development of Arabidopsis, we transformed Arabidopsis plants with an overexpression vector containing an aspen SUS gene (PtrSUS1). The genomic PCR confirmed the successful integration of PtrSUS1 transgene in the Arabidopsis genome. PtrSUS1 expression in transgenic Arabidopsis plants was confirmed by RT-PCR. The SUS activity was dramatically increased in all transgenic lines examined. The three selected transgenic PtrSUS1 lines exhibited faster growth and flowered about 10 days earlier compared to untransformed controls, and also possessed 133%, 139%, and 143% SUS activity compared to controls. Both fresh weights and dry biomass yields of the whole plants from these three selected transgenic lines were significantly increased to 125% of the controls. Transgenic PtrSUS1 lines also had a higher tolerance to higher concentration of sucrose which was reflective of the increased SUS activity in transgenic versus wild-type plants. The growth differences between wild-type and transgenic plants, either in root and hypocotyl length or in fresh and dry weight of whole plant, became more pronounced on the media containing higher sucrose concentrations. Taken together, these results showed that the early flowering, faster growth and increased tolerance to higher sucrose in transgenic lines were caused by the genome integration and constitutive expression of the aspen PtrSUS1 gene in transgenic Arabidopsis.

Cloning the Promoter of BcNA1 from Brassica napus and Fad2 Gene from Arabidopsis thaliana and Construction of the Plant Expression Vector

The upstream regulatory region of a seed specific gene was isolated from the genomic DNA of Brassica napus by PCR amplification. The cloned fragment contained 1755 nucleotides, and shared a sequence homology of 99.6% with the reported data. The coding region of oleic acid desaturase gene was then cloned from Arabidopsis thaliana. The sequencing analysis indicated that the sequence of the PCR product was just the same as reported before. In addition, the plant expression vector harboring the seed specific promoter and trans Fad2 gene was constructed.

黑腐病菌(Xanthomonas campestris)与拟南芥(Arabidopsis thaliana)品种间的致病性测定

甘蓝黑腐病菌(Xanthomonas campeatris pv.campestris)主要以十字花科植物为寄主.引起黑腐病的病原菌,是在世界范围对农业造成严重危害的病原菌之一.拟南芥(Arabidopsis thaliana)是十字花科植物,做为经典遗传学实验材料已有40多年历史.它具有较少染色体组和重复 DNA 序列,易诱变、易种植、个体小、

Ethylene response factor BnERF2-like (ERF2.4) from Brassica napus L.enhances submergence tolerance and alleviates oxidative damage caused by submergence in Arabidopsis thaliana

Ethylene response factor proteins play an important role in regulating a variety of stress responses in plants,but their exact functions in submergence stress are not well understood.In this study,we isolated BnE RF2.4 from Brassica napus L.to study its function in submergence tolerance.The expression of the BnE RF2.4 gene in B.napus and the expression of antioxidant enzyme genes in transgenic Arabidopsis were analyzed by quantitative RT-PCR.The expression of BnE RF2.4 was induced by submergence in B.napus and the overexpression of BnE RF2.4 in Arabidopsis increased the level of tolerance to submergence and oxidative stress.A histochemical method detected lower levels of H_2O_2,O^(·-)_2and malondialdehyde(MDA) in transgenic Arabidopsis.Compared to the wild type,transgenic lines also had higher soluble sugar content and higher activity of antioxidant enzymes,which helped to protect plants against the oxidative damage caused by submergence.It was concluded that BnE RF2.4 increased the tolerance of plants to submergence stress and may be involved in regulating soluble sugar content and the antioxidant system in defense against submergence stress.

In vitro demonstration of interactions among zinc-binding domains of cellulose synthases in Arabidopsis and aspen

Plant cellulose synthases (CesAs) are the key enzymes necessary for cellulose biosynthesis. In Arabidopsis, two distinct groups of three CesAs each are necessary for cellulose synthesis during primary and secondary cell wall formation. It has also been suggested that such three CesAs interact with each other to form plasma-membrane bound rosette complexes that are functional during cellulose production. However, in vivo demonstration of such assemblies of three CesAs into rosettes has not been possible. We used yeast two-hybrid assays to demonstrate the possible interactions among several CesAs from Arabidopsis and aspen via their N-terminal zinc-binding domains (ZnBDs). While strong positive interactions were detected among ZnBDs from secondary wall associated CesAs of both Arabidopsis and aspen, the intergeneric interactions between Arabidopsis and aspen CesAs were weak. Moreover, in aspen, three primary wall associated CesA ZnBDs positively interacted with each other as well as with secondary CesAs. These results suggest that ZnBDs from either primary or secondary CesAs, and even from different plant species could interact but are perhaps insufficient for specificities of such interactions among CesAs. These observations suggest that some other more specific interacting regions might exist within CesAs. It is also possible that some hitherto unknown mechanism exists in plants for assembling the rosette complexes with different compositions of CesAs. Understanding how cellulose is synthesized will have a direct impact on utilization of lignocellulosic biomass for bioenergy production.

Biochemical and Physiological Responses of Arabidopsis thaliana Leaves to Moderate Mechanical Stimulation

Mechanical stimulation of plants can be caused by various abiotic and biotic environmental factors.Apart from the negative consequences,it can also cause positive changes,such as acclimatization of plants to stress conditions.Therefore,it is necessary to study the physiological and biochemical mechanisms underlying the response of plants to mechanical stimulation.Our aim was to evaluate the response of model plant Arabidopsis thaliana to a moderate force of 5 N(newton)for 20 s,which could be compared with the pressure caused by animal movement and weather conditions such as heavy rain.Mechanically stimulated leaves were sampled 1 h after exposure and after a recovery period of 20 h.To study a possible systemic response,unstimulated leaves of treated plants were collected 20 h after exposure alongside the stimulated leaves from the same plants.The effect of stimulation was assessed by measuring oxidative stress parameters,antioxidant enzymes activity,total phenolics,and photosynthetic performance.Stimulated leaves showed increased lipid peroxidation 1 h after treatment and increased superoxide dismutase activity and phenolic oxidation rate after a 20-h recovery period.Considering photosynthetic performance after the 20-h recovery period,the effective quantum yield of the photosystem II was lower in the stimulated leaves,whereas photochemical quenching was lower in the unstimulated leaves of the treated plants.Nonphotochemical quenching was lower in the stimulated leaves 1 h after treatment.Our study suggested that plants sensed moderate force,but it did not induce pronounced change in metabolism or photosynthetic performance.Principal component analysis distinguished three groups–leaves of untreated plants,leaves analysed 1 h after stimulation,while stimulated and unstimulated leaves of treated plants analysed 20 h after treatment formed together the third group.Observed grouping of stimulated and unstimulated leaves of treated plants could indicate signal transduction from the stimulated to distant leaves,that is,a systemic response to a local application of mechanical stimuli.

Individual Leaf Area of Early Flowering Arabidopsis Genotypes Is More Affected by Drought than Late Flowering Ones: A Multi-Scale Analysis in 35 Genetically Modified Lines

Plants acclimate to drought optimizing the trade-off between biomass production and water loss while ensuring their survival and reproduction. Plants also modify their growth or phenology as complementary strategies in response to stress. Despite evidence of an interaction between flowering time and plant growth response to environmental stresses, this interaction in response to drought is under debate. To contribute to the analysis of this interaction, leaf growth of 35 genetically modified lines of Arabidopsis thaliana and their common wild-type, Col-0 was analyzed by a quantitative multi-scale phenotyping approach from cellular to whole plant scale both in well-watered and soil moderate water deficit conditions. These genotypes were selected for the various physiological functions potentially altered by their genetic modification and that could interact with plant growth and/or their drought responses. In all genotypes, leaf expansion decreased in response to drought both at the whole rosette and the individual leaf levels. Additionally, epidermal cell area and/or epidermal cell number decreased in response to the drought treatment. In contrast, the number of rosette leaves was reduced in only half of the genotypes and leaf growth duration was only modified in 4 of them. Despite long photoperiod conditions, the duration of the vegetative phase, i.e. the time elapsed between germination and flowering stage, varied from 12 to 27 days among genotypes under well watered conditions. Our analyses revealed that the differences of flowering time observed in well-watered condition impacted the leaf area response to drought. Early-flowering genotypes slightly decreased their final leaf number, but strongly reduced their individual leaf area compared with the late-flowering ones. This result underlines the difficulty to analyze plant response to environmental stresses when genotypes with different flowering dates are compared.

Potassium channel α-subunit AtKC1 negatively regulates AKTl-mediated K^＋ uptake in Arabidopsis roots under Iow-K^＋ stress

Potassium transporters play crucial roles in K^＋ uptake and translocation in plants. However, so far little is known about the regulatory mechanism of potassium transporters. Here, we show that a Shaker-like potassium channel AtKC1, encoded by the AtLKT1 gene cloned from the Arabidopsis thaliana low-K^＋ （LK）-tolerant mutant Atlktl, significantly regulates AKTl-mediated K^＋ uptake under LK conditions. Under LK conditions, the Atkcl mutants maintained their root growth, whereas wild-type plants stopped their root growth. Lesion of AtKC1 significantly enhanced the tolerance of the Atkcl mutants to LK stress and markedly increased K^＋ uptake and K^＋ accumulation in the Atkclmutant roots under LK conditions. Electrophysiological results showed that AtKC1 inhibited the AKT1-mediated inward K^＋ currents and negatively shifted the voltage dependence of AKT1 channels. These results demonstrate that the ‘silent＇ K^＋ channel α-subunit AtKC1 negatively regulates the AKTl-mediated K^＋ uptake in Arabidopsis roots and consequently alters the ratio of root-to-shoot under LK stress conditions.

The role of AtGPDHc2 in regulating cellular redox homeostasis of Arabidopsis under salt stress

Plants glycerol-3-phosphate dehydrogenase(GPDH)catalyzes the formation of glycerol-3-phosphate,and plays an essential role in glycerolipid metabolism and stress responses.In the present study,the knock-out mutants of cytosolic GPDH(AtGPDHc2)and wild-type Arabidopsis plants were treated with 0,50,100,and 150 mmol L–1 NaCl to reveal the effects of AtGPDHc2 deficiency on salinity stress responses.The fluctuation in redox status,reactive oxygen species(ROS)and antioxidant enzymes as well as the transcripts of genes involved in the relevant processes were measured.In the presence of 100 and 150 mmol L–1 NaCl treatments,AtGPDHc2-deficient plants exhibited a pronounced reduction in germination rate,fresh weight,root length,and overall biomass.Furthermore,loss of AtGPDHc2 resulted in a significant perturbation in cellular redox state(NADH/NAD+and AsA/DHA)and consequent elevation of ROS and thiobarbituric acid-reactive substances(TBARS)content.The elevated ROS level triggered substantial increases in ROS-scavenging enzymes activities,and the up-regulated transcripts of the genes(CSD1,sAPX and PER33)encoding the antioxidant enzymes were also observed.In addition,the transcript levels of COX15,AOX1A and GLDH in gpdhc2 mutants decreased in comparison to wild-type plants,which demonstrated that the deficiency of AtGPDHc2 might also has impact on mitochondrial respiration under salt stress.Together,this work provides some new evidences on illustrating the roles of AtGPDHc2 playing in response to salinity stress by regulating cellular redox homeostasis,ROS metabolism and mitochondrial respiration.

<i>At</i>L1 a Non-LTR Retrotrasposon Fragment in the Genome of <i>Arabidopsis thaliana </i>with Homology to Plants and Animals

We report the isolation of AtL1, a 249 bp non-LTR retrotransposon fragment from Arabidopsis thaliana by fingerprinting mRNAs extracted from A. thaliana plants, ecotype Columbia, in different heat stress conditions. Southern blot and PCR analysis suggested that AtL1 occurs as a single- or low-copy insert in the genome of A. thaliana ecotype Columbia. The presence of AtL1 in the genome of different Arabidopsis ecotypes was confirmed by PCR amplification and sequencing thus excluding all possible contamination. A preliminary scan of the AtL1 nucleotide sequence against the EMBL and NCBI databases revealed a high degree of similarity to a group of LINE type L1 retrotransposons of mammals and with a cDNA sequence of Artemisia annua. A phylogenetic analysis of LINE elements from animals and plants placed AtL1 and A. annua sequences in close proximity to some mammalian sequences but distant from the other plants LINE elements including those from Arabidopsis.

Overexpression of Wheat TaELF3-1BL Delays Flowering in Arabidopsis

EARLY FLOWERING 3(ELF3),a light zeitnehmer(time-taker)gene,regulates circadian rhythm and photoperiodic flowering in Arabidopsis,rice,and barley.The three orthologs of ELF3(TaELF3-1AL,TaELF3-1BL,and TaELF3-1DL)have been identified in wheat too,and one gene,TaELF3-1DL,has been associated with heading date.However,the basic characteristics of these three genes and the roles of the other two genes,TaELF3-1BL and,TaELF3-1AL,remain unknown.Therefore,the present study obtained the coding sequences of the three orthologs(TaELF3-1AL,TaELF3-1BL,and TaELF3-1DL)of ELF3 from bread wheat and characterized them and investigated the role of TaELF3-1BL in Arabidopsis.Protein sequence comparison revealed similarities among the three TaELF3 genes of wheat;however,they were different from the Arabidopsis ELF3.Real-time quantitative PCR revealed TaELF3 expression in all wheat tissues tested,with the highest expression in young spikes;the three genes showed rhythmic expression patterns also.Furthermore,the overexpression of the TaELF3-1BL gene in Arabidopsis delayed flowering,indicating their importance in flowering.Subsequent overexpression of TaELF3-1BL in the Arabidopsis ELF3 nonfunctional mutant(elf3 mutant)eliminated its early flowering phenotype,and slightly delayed flowering.The wild-type Arabidopsis overexpressing TaELF3-1BL demonstrated reduced expression levels of flowering-related genes,such as CONSTANS(AtCO),FLOWERING LOCUS T(AtFT),and GIGANTEA(AtGI).Thus,the study characterized the three TaELF3 genes and associated TaELF3-1BL with flowering in Arabidopsis,suggesting a role in regulating flowering in wheat too.These findings provide a basis for further research on TaELF3 functions in wheat.

Expressional Profiling of Genes Related to Cotton Fiber Initiation and Isolation of GHIAA16 Homologus to Arabidopsis IAA16

The Aux/IAA genes are rapidly and specificallyinduced by the plant hormone auxin and encodeshort-lived nuclear proteins that are capable offorming homo-and hetero-dimer.Molecular,biochemical,and genetic data suggest that theyplay a central role in auxin signaling and plantdevelopment.In order to investigate

The Benefits of Exogenous NO: Enhancing <i>Arabidopsis</i>to Resist <i>Botrytis cinerea</i>

Botrytis cinerea is a necrotrophic fungal pathogen that impacts a wide range of hosts, including Arabidopsis. Pretreatment with nitric oxide (NO) donor sodium nitroprusside (SNP) on Arabidopsis leaves suppressed Botrytis cinerea infection development. Additionally, in this study the dosage levels of SNP applied to the leaves had no direct, toxic impact on the development of the pathogen. The relationship between NO and reactive oxidant species (ROS) was studied by using both spectrophotometrical methods and staining leaf material with fluorescent dyes, nitro blue tetrazolium (NBT), and with 3,3-diaminobenzidine (DAB). The results showed that exogenous NO restrained the generation of ROS, especially H2O2, as the pathogen interacted with the Arabidopsis plant. And this inhibition of reactive oxidant burst coincided with delay infection development in NO-supplied leaves. The influence of elevated level of NO on antioxidant enzymes was investigated in this study. The activities of catalase (CAT) and guaiacol peroxidase (POD) were increased to different degrees in both: 1) SNP treated only leaves, and 2) SNP pretreated leaves that were subsequently inoculateted with pathogens. However, the activity of superoxide dismutase (SOD) was unchanged in the leaves studied. The decrease in H2O2 content probably resulted from the increase in activities of POD and CAT. Our study suggests that NO might trigger some metabolic reactions, i.e. enhanced enzyme activity that restrains H2O2 which ultimately results in resistance to B. cinerea infection.

Minor modifications in obtainable Arabidopsis floral dip method enhances transformation efficiency and production of homozygous transgenic lines harboring a single copy of transgene

Many researchers have developed various methods for in-planta or floral dip transformation of Arabidopsis thaliana, one of the simple protocol and widely used to produce transgenic Arabidopsis. As the efficiency and ease of getting a transformant is very much time consuming effort and less number of the transformants people get, we have developed a little modified transformation protocol to avoid the disparities. Four types of inoculums (inoculum1, inoculum2, inoculum3 and inoculum4) were used to check the transformation efficiency out of which Inoculum3 showed the highest rate of transformation among the four types. 0.07% Twin-20 also acts in same manner as silwet L-77 to increase the rate of transformation efficiency and glucose instead of sucrose can be used in inoculum to transform Arabidopsis. After vacuum infiltration keeping the Agrobacterium infected plants for 7-8 hrs horizontally in low light at 280C temperature condition, considered best to get an increased number of transformed seeds. Modified protocol produced ~12-14% increase in transformants. Selection pots (kanamycin supplemented soil filled pots) in place of selection plates (Kanamycin supplemented Murashige and Skoog agar plates) proved beneficial as no MS medium and no aseptic condition is required for selection of transformed plants. This increase in transformation efficiency consequently increased the percentage of homozygous and single copied stable transgenic lines.

Arabidopsis NIMIN1,2 mediate redox homeostasis and JA/ET pathways to modulate Botrytis cinerea resistance

Arabidopsis NIM1-INTERACTING1 (NIMIN1) and NIMIN2 are required for salicylic acid (SA)-dependent resistance against biotrophic pathogens. In this study, we have demonstrated that NIMIN1, 2 are also essential for plant defense response to necrotrophic pathogen Botrytis cinerea. The nimin1 and nimin2 mutants displayed a higher susceptibility against B. cinerea than the wild type, which correlated with a decrease in B. cinerea-induced PDF).2 expression. Mutation in NIMIN1 or NIMIN2 enhanced accumulation of hydrogen peroxide (H_2O_2) with reductions in the activities of three main antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) at the early time (24h) of upon B. cinerea infection. These mutations also resulted in a visible decrease in B.cinerea-induced Ethylene Responsive Factor 1 (ERF1), Octadecanoid-Responsive Arabidopsis AP2/ERF 59 (ORA59), Allene Oxide Cyclase (AOC3), Opda Reductase 3 (OPR3),ACC Synthesis 2 (ACS2) and ACS6 expression, but an advance in MYC2 expression,indicating that NIMIN1,2 are essential for B. cinerea-activated jasmonic acid (JA)/ethylene(ET) biosynthesis and signaling. However, mutation in NIMIN1 or NIMIN2 drastically suppressed JA-, but not ET-activated PDF1.2 expression. Together, these results suggest that NIMIN1,2 may positively control the B. cinerea resistance by mediating redox homeostasis and JA/ET pathways in Arabidopsis.

Cortical Microtubule Reorientation and Its Relation to Cell Surface Texture of Epidermal Cells of Arabidopsis Thaliana Hypocotyls under Simulated Microgravity Conditions

Gravitropic curvature growth of Arabidopsis hypocotyls mainly occurred in the rapid growing Elongation Zone(EZI),not in the slow-growing Elongation Zone(EZII).By examining reorientation of Microtubules(MT)and phenotype of the cell wall in the EZI and the EZII of Arabidopsis hypocotyls under normal gravitational condition,it is found that MTs in the rapid growing epidermal cells were mainly in the transverse direction,while those in the non-growing epidermal cells were in the longitudinal directions.However,this difference in cortical MT arrays between the EZI and EZII cells disappeared when the seedlings were exposed to the simulated microgravity condition on a horizontal clinostat.Field emission scanning electron microscopy revealed that the surface texture of epidermal cells,like the direction of the MT,in the EZI and the EZII also became similar when exposed to the simulated microgravity condition.This result indicated that simulate microgravity could modify the potential differentiation between the EZI and the EZII by affecting the orientation of cortical MT in the epidermal cells.