Regulation of jasmonate signaling by reversible acetylation of TOPLESS in Arabidopsis

The plant hormone jasmonate(JA)regulates plant immunity and adaptive growth by orchestrating a genome-wide transcriptional program.Key regulators of JA-responsive gene expression include the master transcription factor MYc2,which is repressed by the conserved Groucho/Tup1-like corepressor TOPLESS(TPL)in the resting state.However,the mechanisms underlying TPL-mediated transcriptional repression of MYc2 activity and hormone-dependent switching between repression and de-repression remainenigmatic.Here,we report the regulation of TPLactivity and JAsignaling byreversibleacetylation of TPL.We found that the histone acetyltransferase GCN5 could mediate TPL acetylation,which enhances its interaction with the NOVEL-INTERACTOR-OF-JAZ(NINJA)adaptor and promotes its recruitment to MYc2 target promoters,facilitating transcriptional repression.Conversely,TPL deacetylation by the histonedeacetylase HDA6 weakens TPL-NINJA interaction and inhibitsTPL recruitmentto MYC2 target promoters,facilitating transcriptional activation.In the resting state,the opposing activities of GCN5 and HDA6 maintain TPL acetylation homeostasis,promoting transcriptional repression activity of TPL.In response to JA elicitation,HDA6 expression is transiently induced,resulted in decreased TPL acetylation and repressor activity,thereby transcriptional activation of MYC2 target genes.Thus,the GCN5-TPL-HDA6 module main tains the homeostasis of acetylated TPL,thereby determining the transcriptional state of JA-responsive genes.Our findings uncovered a mechanism by which the TPL corepressor activity in JA signaling is activelytuned inarapidandreversiblemanner.

TOPLESS promotes plant immunity by repressing auxin signaling and is targeted by the fungal effector Naked1

In plants,the antagonism between growth and defense is hardwired by hormonal signaling.The perception of pathogen-associatedmolecularpatterns(PAMPs)frominvadingmicroorganismsinhibits auxin signalingand plant growth.Conversely,pathogens manipulate auxin signaling to promote disease,but how this hormone inhibits immunity is not fully understood.Ustilago maydis is a maize pathogen that induces auxin signaling in its host.We characterized a U.maydis effector protein,Naked1(Nkd1),that is translocated into the host nucleus.Through its native ethylene-responsive element binding factor-associated amphiphilic repression(EAR)motif,Nkd1 binds to the transcriptional co-repressors TOPLESS/TOPLESS-related(TPL/TPRs)and prevents the recruitment of a transcriptional repressor involved in hormonal signaling,leading to the derepression of auxin and jasmonate signaling and thereby promoting susceptibility to(hemi)biotrophic pathogens.A moderate upregulation of auxin signaling inhibits the PAMP-triggered reactive oxygen species(ROS)burst,an early defense response.Thus,our findings establish a clear mechanism for auxin-induced pathogen susceptibility.Engineered Nkd1 variants with increased expression or increased EAR-mediated TPL/TPR binding trigger typical salicylic-acid-mediated defense reactions,leading to pathogen resistance.This implies that moderate binding of Nkd1 to TPL is a result of a balancing evolutionary selection process to enable TPL manipulation while avoiding host recognition.

清至民国时期汉族无顶童帽研究

无顶童帽是中国传统儿童服饰品之一,其历史悠久,至清代及民国时期仍非常流行,但由于当代蓄发制度的废除无顶童帽的佩戴也逐渐变少。现以江南大学汉族民间服饰传习馆的实物为研究基础,并且结合历史史料和绘画作品对清至民国时期无顶童帽的造型、装饰特征,以及其佩戴的季节、场合、人群进行研究,探索无顶童帽的功能及装饰等意义。研究表明,清至民国时期无顶童帽在佩戴时有男女儿童的区分;款式变化可以适应季节变化的需要,佩戴时间较长,除外出佩戴外更具居家功能。此外无顶帽较其他童帽具有独特的装饰价值和实用价值,其在保暖的同时又具透气性,满足了儿童生长需要,并且结合近代儿童发式特点,可满足装饰、固发、礼仪等多方面的需要。

等距型面成形原理与数控磨削方法研究

对等距型面的成形原理和数控磨削加工方法进行了系统深入的研究。应用微分几何理论,导出了等距曲线的方程,证明了它是具有任意两条平行切线之间距离都相等的卵形线.指出从应用的角度考虑,以等距曲线为型面曲线形成的等距型面、等距拟锥面加工和测量方便,具有实用价值.针对等距型面和等距拟锥面的特点,提出了数控加工及数控程序编制方法,为等距型面和等距拟锥面的加工及数控磨床的运动设计提供了理论基础.

Study of CNC Grinding Machining Method About Isometric Polygon Profile

The formed principle and CNC grinding machining method of isometric polygonal profile are studied deeply and systematically. Equation about section curve of isometric polygon profile is set up by means of geometric principle. With the use of differential geometry theory, the curve is proved to be with geometric feature of convex curve. It is referred to as Isometric Polygonal Curve (IPC), because that is a kind of convex curve on which the distance between any parallel tangent lines is equal. Isometric Polygonal Profile (IPP) or Isometric Polygonal Cone Profile (IPCP) or Isometric Polygonal Topless Cone (IPTC) is formed with the IPC and straight line as generating curve. But the machining and measuring of the IPCP are so inconvenient that it has little value. Keeping in mind the characteristic of the IPP and IPTC, this paper puts forward the program method of CNC grinding machining. Isometric polygonal profile connection is a kind of polygonal profile connection. It has the superiority over keys (prismatic key & spline etc), and can be suit for the situations such as high rotative velocity, large torque, high precision, and small fixed room and vibration. Nowadays, some countries such as America, Russia, German and Switzerland applied CNC machining to the machining of polygon surface coupling parts, which makes their applications in machine productions such as motor engine, heavy machine increase day by day. But reports about concrete machining technology of isometric polygonal profile and programming of CNC machining program are very few. CNC grinding of the IPP and IPTC is one kind of the precision machining technology. It is of great importance to the popularization of the IPP and IPTC connection. From the forming mechanism, we can see that the machining and measuring of the IPP and IPTC are convenient, and therefore they have the value of the popularization. But the machining and measuring of the IPCP are so inconvenient that it has little value. In the programming the CNC grinding of the IPP and IPTC, it is more reasonable to calculate the coordinate of node according to the approaching method of equal error arc. According to the method of CNC grinding mentioned above to design the grinding machine, the structure is simple and of economical and practical.

一种无底坑、无顶层高度的船用升降机实现方法

船用环境下,由于升降机的井道空间(包括底坑深度、顶层高度)资源紧张,导致物流输送任务路径受限制。为了提高井道空间利用率,可采用直线电动机强制驱动,并通过分段提升的方式,实现井道无底坑、无顶层高度的布置需求。文章分析了无底坑、无顶层高度的船用升降机的需求,介绍了实现方法和关键技术,并制造原理样机加以验证。

平头塔机起重臂架截面型式及其上翘度控制

对平头塔机起重臂架的不同截面型式进行对比,总结制造经验及工艺控制要点,使其拼焊环节质量得到有效保证,确保符合设计要求。

略论唐朝时期外来服饰对汉服饰的影响

唐朝时期的汉服在性质、色彩上有很多前所未有的变化,这是受到外来服饰影响并与之相融合而产生的结果。文章以文献资料、壁画、绘画等为依据,研究外来服饰对汉服的影响,指出唐朝时期汉服受外来服饰影响,一是外来使节、商人等在华传播其本土文化,二是唐人善于吸纳外来文化,是两者共同影响下所产生的结果。

NAC1 regulates root ground tissue maturation by coordinating with the SCR/SHR-CYCD6;1 module in Arabidopsis

Precise spatiotemporal control of the timing and extent of asymmetric cell divisions(AcDs)is essential for plant development.In the Arabidopsis root,ground tissue maturation involves an additional AcD of the endo-dermis that maintains the inner cell layer as the endodermis and generates the middle cortex to the outside.Through regulation of the cell cycle regulator CYCLIND6;1(CYCD6;1),the transcription factors SCARECROW(SCR)and SHORT-ROOT(SHR)play critical roles in this process.In the present study,we found that loss of function of NAC1,a NAC transcription factor family gene,causes markedly increased periclinal cell divisions in the root endodermis.Importantly,NAC1 directly represses the transcription of CYCD6;1 by recruiting the co-repressor TOPLESS(TPL),creating a fine-tuned mechanism to maintain proper root ground tissue patterning by limiting production of middle cortex cells.Biochemical and genetic analyses further showed that NAC1 physically interacts with SCR and SHR to restrict excessive periclinal cell divisions in the endo-dermis during root middle cortex formation.Although NAC1-TPL is recruited to the CYCD6;1 promoter and represses its transcription in an SCR-dependent manner,NAC1 and SHR antagonize each other to regu-late the expression of CYCD6;1.Collectively,our study provides mechanistic insights into how the NAC1-TPL module integrates with the master transcriptional regulators SCR and SHR to control root ground tissue patterning by fine-tuning spatiotemporal expression of CYCD6;1 in Arabidopsis.

SIZ1-Mediated SUMOylation of TPR1 Suppresses Plant Immunity in Arabidopsis

Plant immune responses are tightly regulated to ensure their appropriate deployment. Overexpression of TOPLESS-RELATED 1 (TPR1), a SUPPRESSOR OF npr1-1, CONSTITUTIVE 1 (SNC1)-interacting protein, results in autoimmunity that reduces plant growth and development. However, how TPR1 activity is regulated remains unknown. Loss of function of SIZ1, a (SUMO) E3 ligase, induces an autoimmune response, partially due to elevated SNC1 levels. Here we show that SNC1 expression is upregulated in Arabidopsis thaliana siz1-2 due to positive-feedback regulation by salicylic acid. SIZ1 physically interacts with TPR1 and facilitates its SUMO modification. The K282 and K721 residues in TPR1 serve as critical SUMO attachment sites. Simultaneous introduction of K282R and K721R substitutions in TPR1 blocked its SUMOylation, enhaneed its transcriptional co-repressor activity, and increased its association with HISTONE DEACETYLASE 19 (HDA19), suggesting that SUMOylation of TPR1 represses its transcriptional co-repressor activity and inhibits its interaction with HDA19. In agreement with this finding, the simultaneous introduction of K282R and K721R substitutions enhanced TPR1 mediated immunity, and the tpr1 mutation partially suppressed autoimmunity in siz1-2. These results demonstrate that SIZ1-mediated SUMOylation of TPR1 represses plant immunity, which at least partly contributes to the suppression of autoimmunity under nonpathogenic conditions to ensure proper plant development.

The SlTPL3–SlWUS module regulates multi-locule formation in tomato by modulating auxin and gibberellin levels in the shoot apical meristem

Malformed fruits depreciate a plant’s market value.In tomato(Solanum lycopersicum),fruit malformation is associated with the multi-locule trait,which involves genes regulating shoot apical meristem(SAM)development.The expression pattern of TOPLESS3(SITPL3)throughout SAM development prompted us to investigate its functional significance via RNA interference(RNAi)and clustered regularly interspaced short palindromic repeats/CRISPR-associated nuclease 9(Cas9)-mediated gene editing.Lower SITPL3 transcript levels resulted in larger fruits with more locules and larger SAMs at the 5 d after germination(DAG5)stage.Differentially expressed genes in the SAM of wild-type(WT)and SITPL3-RNAi plants,identified by transcriptome deep sequencing(RNA-seq),were enriched in the gibberellin(GA)biosynthesis and plant hormone signaling pathways.Moreover,exogenous auxin and paclobutrazol treatments rescued the multi-locule phenotype,indicating that SITPL3 affects SAM size by mediating auxin and GA levels in the SAM.Furthermore,SITPL3 interacted with WUSCHEL(SIWUS),which plays an important role in SAM size maintenance.We conducted RNA-seq and DNA affinity purification followed by sequencing(DAP-seq)analyses to identify the genes regulated by SITPL3 and SIWUS in the SAM and to determine how they regulate SAM size.We detected24 overlapping genes regulated by SITPL3 and SIWUS and harboring an SIWUS-binding motif in their promoters.Furthermore,functional annotation revealed a notable enrichment for functions in auxin transport,auxin signal transduction,and GA biosynthesis.Dual-luciferase assays also revealed that SITPL3 enhances SIWUS-mediated regulation(repression and activation)of SIPIN3 and SIGA2 ox4 transcription,indicating that the SITPL3-SIWUS module regulates SAM size by mediating auxin distribution and GA levels,and perturbations of this module result in enlarged SAM.These results provide novel insights into the molecular mechanism of SAM maintenance and locule formation in tomato and highlight the SITPL3-SIWUS module as a key regulator.