A glycine-rich nuclear effector VdCE51 of Verticillium dahliae suppresses plant immune responses by inhibiting the accumulation of GhTRXH2

Verticillium dahliae is an important soil-borne fungal pathogen that causes great yield losses in many cash crops.Effectors of this fungus are known to regulate plant immunity but the mechanism much remains unclear.A glycine-rich nuclear effector,VdCE51,was able to suppress immune responses in tobacco against Botrytis cinerea and Sclerotinia sclerotiorum.This effector was a required factor for full virulence of V.dahliae,and its nuclear localization was a requisite for suppressing plant immunity.The thioredoxin GhTRXH2,identified as a positive regulator of plant immunity,was a host target of VdCE51.Our findings show a virulence regulating mechanism whereby the secreted nuclear effector VdCE51 interferes with the transcription of PR genes,and the SA signaling pathway by inhibiting the accumulation of GhTRXH2,thus suppressing plant immunity.

The Magnaporthe oryzae effector Avr-PikD suppresses rice immunity by inhibiting an LSD1-like transcriptional activator

Avirulence effectors(Avrs),encoded by plant pathogens,can be recognized by plants harboring the corresponding resistance proteins,thereby initiating effector-triggered immunity(ETI).In susceptible plants,however,Avrs can function as effectors,facilitating infection via effector-triggered susceptibility(ETS).Mechanisms of Avr-mediated ETS remain largely unexplored.Here we report that the Magnaporthe oryzae effector Avr-PikD enters rice cells via the canonical cytoplasmic secretion pathway and suppresses rice basal defense.Avr-PikD interacts with an LSD1-like transcriptional activator AKIP30 of rice,and AKIP30 is also a positive regulator of rice immunity,whereas Avr-PikD impedes its nuclear localization and suppresses its transcriptional activity.In summary,M.oryzae delivers Avr-PikD into rice cells to facilitate ETS by inhibiting AKIP30-mediated transcriptional regulation of immune response against M.oryzae.

Yersinia type Ⅲ effectors perturb host innate immune responses

The innate immune system is the first line of defense against invading pathogens. Innate immune cells recognize molecular patterns from the pathogen and mount a response to resolve the infection. The production of proinflammatory cytokines and reactive oxygen species, phagocytosis, and induced programmed cell death are processes initiated by innate immune cells in order to combat invading pathogens. However, pathogens have evolved various virulence mechanisms to subvert these responses. One strategy utilized by Gram-negative bacterial pathogens is the deployment of a complex machine termed the type Ⅲ secretion system(T3SS). The T3SS is composed of a syringe-like needle structure and the effector proteins that are injected directly into a target host cell to disrupt a cellular response. The three human pathogenic Yersinia spp.(Y. pestis, Y. enterocolitica, and Y. pseudotuberculosis) are Gramnegative bacteria that share in common a 70 kb virulence plasmid which encodes the T3 SS. Translocation of the Yersinia effector proteins(YopE, YopH, YopT, YopM, YpkA/YopO, and YopP/J) into the target host cell results in disruption of the actin cytoskeleton to inhibit phagocytosis, downregulation of proinflammatory cytokine/chemokine production, and induction of cellular apoptosis of the target cell. Over the past 25 years, studies on the Yersinia effector proteins have unveiled tremendous knowledge of how the effectors enhance Yersinia virulence. Recently, the long awaited crystal structure of YpkA has been solved providing further insights into the activation of the YpkA kinase domain. Multisite autophosphorylation by YpkA to activate its kinase domain was also shown and postulated to serve as a mechanism to bypass regulation by host phosphatases. In addition, novel Yersinia effector protein targets, such as caspase-1, and signaling pathways including activation of the inflammasome were identified. In this review, we summarize the recent discoveries made on Yersinia effector proteins and their contribution to Yersinia pathogenesis.

Effects of Nine Kinds of Household Vase Solutions on Fresh-keeping Effect of Lilium Cut Flowers

[Objective]The paper was to study the effects of nine kinds of household vase solutions on fresh-keeping effect of Lilium cut flowers.[Method]Using Lilium"Sorbonne"as the material,nine kinds of household vase solutions were prepared by edible white granulated sugar,white vinegar,akafen powder and vitamin C tablets,respectively.The morphological and physiological indexes of Lilium cut flowers,including vase life,ornamental grade,flower diameter,fresh weight of flower branches,water balance value,soluble protein content and MDA content of petals,were observed,and the effects of nine kinds of household vase solutions on fresh-keeping effect of Lilium cut flowers were studied.[Result]The household vase solution F8(20 g/L white granated sugar+1 packet/L acafen powder+2 tablets/L vitamin C tablets)had the best fresh-keeping effect on Lilium cut flowers,which was beneficial to prolong the vase life and improve the ornamental value of Lilium cut flowers.[Conclusion]The household vase solution of Lilium cut flowers is optimized,which is not only environmentally friendly but also convenient for ordinary families.

Fresh-keeping Effects of Different Concentrations of 6-BA and B9 on Carnation Cut Flower

Using sucrose, citric acid and vitamin C as the basic liquid, different concentrations of 6-BA and B9 preservatives were added, and the carnation variety ＇ Master＇ was treated. The results showed that the formula of 3% sucrose ＋ 50 mg/L citric acid ＋ 600 mg/L vitamin C ＋ 20 mg/L 6-BA could effectively maintain the water balance of the cut flower, prolong the vase life of the cut flower to 16.4 d, and maximize the flower diameter and the crown height.

Puccinia triticina effector protein Pt_21 interacts with wheat thaumatin-like protein TaTLP1 to inhibit its antifungal activity and suppress wheat apoplast immunity

Puccinia triticina(Pt), as the causal agent of wheat leaf rust, employs a plethora of effector proteins to modulate wheat immunity for successful colonization. Understanding the molecular mechanisms underlying Pt effector-mediated wheat susceptibility remains largely unexplored. In this study, an effector Pt_21 was identified to interact with the apoplast-localized wheat thaumatin-like protein TaTLP1 using a yeast two-hybrid assay and the Pt_21-TaTLP1 interaction was characterized. The interaction between Pt_21 and TaTLP1 was validated by in vivo co-immunoprecipitation assay. A TaTLP1 variant,TaTLP1C71A, that was identified by the site-directed mutagenesis failed to interact with Pt_21. Pt_21was able to suppress Bax-mediated cell death in leaves of Nicotiana benthamiana and inhibit TaTLP1-mediated antifungal activity. Furthermore, infiltration of recombinant protein Pt_21 into leaves of transgenic wheat line overexpressing TaTLP1 enhanced the disease development of leaf rust compared to that in wild-type leaves. These findings demonstrate that Pt_21 suppresses host defense response by directly targeting wheat TaTLP1 and inhibiting its antifungal activity, which broadens our understanding of the molecular mechanisms underlying Pt effector-mediated susceptibility in wheat.

Bioinformatic Analysis of Potential Pathogenicity Effectors of <i>Candidatus</i>Liberibacter asiaticus, Causal Agent of Citrus Huanglongbing

Huanglongbing (HLB) or citrus greening is currently the most important citrus disease, caused by the bacterium Candidatus Liberibacter asiaticus (CLas). The impossibility of isolating it causes understanding its pathogenic mechanisms to be a complicated task. Recent studies identified 16 proteins with the signal peptide needed to be secreted in the plant and cause the disease. The present study aims to perform a bioinformatic analysis of these proteins with the function prediction approach by gene ontology (GO) and the detection of conserved domains. It was observed that of the 16 proteins analyzed not all are found in different infective strains reported in the literature. The GO analysis allowed us to relate different proteins with the biological process of energy and pathogenic activity, especially CLIBASIA_03315 and CLIBASIA_05115, respectively. The domain analysis allowed the observation of a β-CA domain, tentatively related to the damage caused to the chloroplast and a PAAR domain associated with the T6SS secretory system. Our results provide information on the possible function of potential pathogenicity effectors in CLas.

Kiwi Fruit Fresh-keeping Technology

The vitamin C rich-kiwi fruit-the king of fruits-is good to taste but hard to store. Only a few countries can prevent mildew on the fruit stalk during the storage process. The fresh-keeping technology developed by the Shaanxi Teachers University has enabled China to catch up with the advanced countries in this field.

A Meloidogyne incognita effector Minc03329 suppresses plant immunity and promotes parasitism

Meloidogyne incognita is a devastating plant-parasitic nematode.Effectors play important roles during the stages of nematodes infection and parasitism,but their molecular functions remain largely unknown.In this study,we characterized a new effector,Minc03329,which contains signal peptide for secretion and a C-type lectin domain.The yeast signal sequence trap experiments indicated that the signal peptide of Minc03329 is functional.In situ hybridization showed that Minc03329 was specifically expressed in the subventral esophageal gland.Real-time qPCR confirmed that the expression level of Minc03329 transcript was significantly increased in pre-parasitic and parasitic second-stage juveniles(pre-J2s and par-J2s).Tobacco rattle virus(TRV)-mediated gene silencing of Minc03329 in host plants largely reduced the pathogenicity of nematodes.On the contrary,ectopic expression of Minc03329 in Arabidopsis thaliana significantly increased plant susceptibility to nematodes.Transient expression of Minc03329 in Nicotiana benthamiana leaves suppressed the programmed cell death triggered by the pro-apoptotic protein BAX.Moreover,the transcriptome analysis of Minc03329-transgenic Arabidopsis and wild type revealed that many defense-related genes were significantly down-regulated.Interestingly,some different expressed genes were involved in the formation of nematode feeding sites.These results revealed that Minc03329 is an important effector for M.incognita,suppressing host defense response and promoting pathogenicity.

分体刀具式名优茶采摘末端执行器设计与试验优化

针对名优茶机械化采摘过程中侧芽无法采摘的问题,根据顶芽、侧芽及茶梗的相关参数并结合茶园环境设计了一种末端执行器,利用分体式刀具的刀齿弯曲变形适应茶梗的干扰从而采摘侧芽。通过有限元仿真刀具切割侧芽得到采摘成功率的影响因素为刀齿宽度、刀齿长度及刀具厚度;采用三因素三水平的中心组合设计与响应面分析法研究各因素对采摘成功率的交互影响;以采摘成功率为响应值建立二次回归模型,确定各因素对采摘成功率的影响显著性主次排序为:刀齿长度、刀齿宽度、刀具厚度。以采摘成功率为目标对各试验因素进行优化,得到优化后的刀齿宽度、刀具厚度、刀齿长度分别为2.6、0.9、20.0 mm。采用优化后的参数进行茶园采摘试验,结果表明,末端执行器能够有效完成茶叶采摘工作,顶芽、侧芽采摘成功率分别为93%、63%,试验值与预测值的相对误差小于5%,优化模型结果可靠。

植物工厂岩棉块种苗移植机移植部件设计与试验

目前植物工厂岩棉块种苗移植装备自动化程度低,作业时大多依赖于人工,劳动强度大,效率低。基于植物工厂水培叶菜种苗移植现状设计了一种二级变间距的高速移植部件,并配备有一种拨指式定植杯分离辅助机构。对移植手取苗过程中岩棉块种苗进行受力分析,为移植手设计提供依据;开展拨指式定植杯分离辅助机构落杯试验,为后续植苗至栽培槽孔的定植杯中奠定基础。搭建移植机构试验平台,以取苗深度、岩棉块含水率、移植部件横移速度、移植手升降速度、移植手夹苗间距为试验因素进行五因素三水平正交试验,通过方差分析各因素对移植成功率的影响。试验结果表明:当取苗深度为24 mm、岩棉块含水率为90%、移植部件横移速度为0.8 m/s、移植手升降速度为0.24 m/s、移植手夹苗间距为14 mm时,机构移植成功率为97.9%,移植速度为3132株/h,能够满足高速、高效、稳定的植物工厂岩棉块叶菜种苗移植机械化作业的技术需求。

柑桔采摘机器人末端执行器设计与试验

针对现有柑桔采摘机器人末端执行器单果采摘时间长、采摘成功率低等问题,以20SiMnMoV合金结构钢为材料,设计制作了一款柑桔采摘末端执行器。该末端执行器主要由抓取机构、剪切机构、连接架及控制系统等部分组成,通过控制系统,抓取机构可以实现柑桔无损抓取,剪切机构可将果梗与柑桔快速分离。应用CATIA软件建立末端执行器的三维模型,借助UG与ABAQUS软件对其进行模态分析与静强度分析,得到末端执行器在采摘柑桔过程中不会发生共振,最大变形量为0.077 mm,最大应力为853.1 Mpa、小于材料屈服强度。在脐橙园田间采摘试验结果表明,在采摘机器人机械臂姿态的采摘角度为45°,切割刀刃角度为45°,空压机气压为6 kPa时,采摘成功率最高,单果采摘时间接近最小。该柑桔采摘机器人末端执行器采摘速度高,控制难度低,与机械臂集成度高。

丘陵果园自然环境下柑橘采摘机器人设计与试验

智慧果园是未来果园行业发展的趋势,智能化果实采摘是发展智慧果园的关键问题。为实现智能化果实采摘,本文搭建了一种适用于丘陵果园矮化栽培模式下的柑橘采摘机器人系统。针对丘陵果园垄间地面凹凸不平,存在地形倾斜角0°~20°,设计了一种自适应调平平台保持机械臂基座水平;通过视觉系统获取多幅点云图像建立果树的三维点云模型,获取果实位置信息;为避免采摘时造成果实损伤,结合柑橘类水果的采摘特点,设计了一种剪切夹持一体化的末端执行器完成柑橘采摘。针对果园自然环境的主要扰动因素(风和光照)进行分级,设置10组对比试验,结果表明:在低光照或正常光照条件下,平均果实定位准确率为82.5%,末端执行器夹取成功率为87.5%,平均采摘时间最短为12.3 s/个;高光照条件下平均果实定位准确率为72%,末端执行器夹取成功率为80%,平均采摘时间最短为12.5 s/个。

基于TRIZ的猕猴桃采摘机设计

针对猕猴桃采摘效率低、易损伤果实等问题,应用TRIZ理论指导猕猴桃采摘机的设计。通过需求分析,确定猕猴桃采摘机的作业流程。基于系统功能分析识别旋拧式猕猴桃采摘末端执行器的功能缺陷,应用因果分析、物场分析等TRIZ工具对采摘末端执行器求解创新方案,创新设计出一种自动定位果树—识别果实—剪断果梗—收集果实的猕猴桃采摘机。应用ADAMS对末端执行器采摘动作进行步态仿真、应用MATLAB对采摘机作业空间和采摘轨迹进行动态仿真,结果表明:猕猴桃采摘机采摘轨迹空间范围为X方向行程约1.4 m、Y方向行程约1.8 m和Z方向行程约2.3 m;采摘速度为8 s/个,末端执行器采摘过程作业动作平稳连贯,满足预期设计要求。在产品概念设计阶段应用TRIZ理论,有利于产生高质量、多层级的概念解,提高产品设计效率。

废旧锂离子电池搬运机器人末端执行器设计

为了解决废旧锂离子电池回收问题,针对回收过程中的分拣步骤,设计了一种可以承载电池质量并适应不同尺寸的机器人末端执行器。介绍了末端执行器各个机构,并针对肘杆六杆机构进行了进一步校核,建立了六杆机构的运动学模型;使用遗传-BFGS(Genetic Algorithm-BFGS,GABFGS)拟牛顿法和粒子群-BFGS(Particle Swarm Optimization-BFGS,PSO-BFGS)拟牛顿法对六杆机构的杆长及位置参数进行优化,建立了六杆机构的动力学模型,计算并仿真校核了空载所需的驱动力,以及极限条件下搬运过程的径向力。研究提供了一种六杆传动机构的新思路,可为废旧锂离子电池分拣设备的研发提供参考。

基于负压式苹果采摘机器人末端设计及仿真

为提高苹果采摘效率,实现无损化、高效化采摘。设计出一种基于负压式末端执行器的六自由度采摘机器人,并对基于负压式设计的末端结构进行验证。后基于SD-H参数法对机器人进行正逆运动学求解,运用ADAMS仿真软件对采摘机械臂进行运动学和动力学仿真分析。对末端吸口中心点和各关节点进行监控获取末端吸口位移、速度、加速度与各关节力矩曲线。分析曲线表明:机械臂运动过程平稳无突变,采摘苹果产生冲击力对机械臂各关节影响较小,机械结构设计合理,可满足采摘工作需求,并对后续路径规划提供基础依据。

一种搭载机械臂的瓷砖铺贴末端执行器的设计

针对手工铺贴瓷砖成本高、工作效率低、劳动强度大等问题,设计了一种搭载机械臂的瓷砖铺贴末端执行器。设计真空系统实现瓷砖吸放,设计惯性式激振器实现振动压实,利用激光测距传感器与边缘搜索方法检测定位。基于ROS开发了铺贴系统,实现了搭载机械臂的瓷砖铺贴实验。结果表明,该装置能够实现300 mm×300 mm的瓷砖铺贴作业,重复定位标准偏差小于0.343 mm。

机器人制孔末端执行器的设计及静动力学分析

提出了一种新型机器人制孔末端执行器的模块化结构设计方案,阐述了该末端执行器的主要模块结构设计、技术特点和技术参数。针对末端执行器整体和主要结构零件分别进行了有限元静力学及动力学分析计算,分析结果表明结构设计科学合理。同时,进一步揭示了高速制孔末端执行器与其匹配的机器人成本和制孔质量之间的关系,可以为其他类似机器人末端执行器设计提供参考。

基于“治未病”思想探讨中医药调控CREB蛋白防治阿尔茨海默病的作用机制研究进展

阿尔茨海默病是常见的中枢神经退行性疾病,突触功能障碍导致神经元丢失是主要发病机制,然而突触可塑性改变导致的记忆减退在AD发病之前即可出现,这为在AD患者出现不可逆病理损害之前进行干预提供了可能。环磷酸腺苷效应元件结合蛋白(CREB)处于突触强化和记忆形成过程中多条激活通路的中心汇聚点,在人体学习记忆能力的维持中起着关键作用,本文通过回顾近年来同道有关CREB与学习记忆研究及中医药治疗AD现状的文献,分别从CREB与学习记忆的相关通路、参与AD发病机制的实验研究以及中医药防治AD与CREB蛋白的相关性等方面进行整理总结,以期为中医药以CREB蛋白为切入点改善记忆减退进而防治AD提供部分理论及实验依据。