Vacuolar processing enzyme positively modulates plant resistance and cell death in response to Phytophthora parasitica infection

Oomycete, particularly Phytophthora species, causes the most devastating crop diseases, such as potato late blight,and threatens the sustainable crop production worldwide. Our previous studies identified Resistance to Phytophthora parasitica 1(RTP1) as a negative regulator of Arabidopsis resistance to multiple biotrophic pathogens and RTP1 lossof-function plants displayed rapid cell death and reactive oxygen species(ROS) production during early colonization of P. parasitica. In this study, we aim to decipher the mechanism of RTP1-mediated cell death, and identify a member of vaculoar processing enzymes(VPEs), γVPE, playing a role in rtp1-mediated resistance to P. parasitica and cell death occurrence. Our results showed up-regulation of the expression of γVPE as well as increased VPE/caspase 1-like protease activity in P. parasitica-infected rtp1 mutant plants. Besides, we found that the VPE/caspase 1-like protease activity was required for the cell death occurrence in Arabidopsis plants during the infection of P. parasitica as well as rtp1-mediated resistance to P. parasitica. Further pathogenicity assays on either Arabidopsis γvpe mutant plants or leaves of Nicotiana benthamiana with transient overexpression of γVPE demonstrated γVPE could positively affect plant resistance to P. parasitica. Together, our studies suggest that γVPE might function as an important regulator of plant defense and cell death occurrence in response to P. parasitica infection, and VPE/caspase 1-like protease activity is required for rtp1-mediated resistance to P. parasitica.

GmSKP1,a Novel S-phase Kinase-associated Protein 1 in Glycine max,Enhancing Resistance Against Phytophthora sojae Infection

Phytophthora root and stem rot of soybean caused by Phytophthora sojae(P.sojae)is a devastating disease that affects soybean[Glycine max(L.)Merr.]all over the world.S-phase kinase-associated protein 1(SKP1)proteins are key members of the SKP1/Cullin/F-box protein(SCF)ubiquitin ligase complex and play diverse roles in plant biology.However,the role of SKP1 in soybean against the phytopathogenic oomycete P.sojae remains unclear.In this study,a novel member of the soybean SKP1 gene family,GmSKP1 which was significantly induced by P.sojae,was reported.The expression of GmSKP1 was simultaneously induced by methyl jasmonate(MeJA),salicylic acid(SA)and ethylene(ET),which might suggest an important role for GmSKP1 of plant in responses to hormone treatments.Functional analysis using GmSKP1 overexpression lines showed that GmSKP1 enhanced resistance to P.sojae in transgenic soybean plants.Further analyses showed that GmSKP1 interacted with a homeodomain-leucine zipper protein transcription factor(GmHDL56)and a WRKY transcription factor(GmWRKY31),which could positively regulate responses to P.sojae in soybean.Importantly,several pathogenesis-related(PR)genes were constitutively activated,including GmPR1a,GmPR2,GmPR3,GmPR4,GmPR5a and GmPR10,in GmSKP1-OE soybean plants.Taken together,these results suggested that GmSKP1 enhanced resistance to P.sojae in soybean,possibly by activating the defense-related PR genes.

Antibacterial Activity and Mechanisms of Ethanol Extracts from Scutellaria baicalensis Georgi and Magnolia officinalis against Phytophthora nicotianae

Phytophthora nicotianae causes substantial economic losses in most countries where tobacco is produced.At present,the control of P.nicotianae mainly depends on chemical methods,with considerable environmental and health issues.We investigated the effects of ethanol extracts from Scutellaria baicalensis Georgi(SBG)and Magnolia officinalis(MO).On mycelial growth,sporangium formation,and zoospore release of P.nicotianae.Both extracts inhibited the growth of P.nicotianae,with mycelial growth inhibition rates of 88.92%and 93.92%,respectively,at 40 mg/mL,and EC50 values of 5.39 and 5.74 mg/mL,respectively.The underlying mechanisms were the inhibition of sporangium formation,the reduction of zoospore number,and the destruction of the mycelium structure.At an SBG extract concentration of 16.17 mg/mL,the inhibition rates for sporangia and zoospores were 98.66%and 99.39%,respectively.At an MO extract concentration of 2.87 mg/mL,the production of sporangia and zoospores was completely inhibited.The hyphae treated with the two plant extracts showed different degrees of deformation and damage.Hyphae treated with SBG extract showed adhesion and local swelling,whereas treatment with MO extract resulted in broken hyphae.Mixture of the extracts resulted in a good synergistic effect.

Analysis of Population Genetic Change to Single Oospore Strains of Phytophthora infestans

The occurrence of sexual reproduction accelerates the population genetic variation of Phytophthora infestans and makes it more difficult to control.The systematic analysis of the differentiation of phenotype(mating type and metalaxyl sensitivity)and genotype(mtDNA haplotype and SSR genotype)of 65 single oospore strains of P.infestans was carried out in this article.Five test strains were isolated from Heilongjiang Province and Mongolia Autonomous Region.The experiment results showed that the isolation ratio of metalaxyl resistance(MR:HR)of single oospore strains produced through the cross of medium resistance and high resistant parents was 18:13;the isolation ratio of the metalaxyl resistance(S:MR:HR)of single oospore strains produced through the cross of sensitive and high resistant parents was 4:12:7.The progenies of single oospore strains produced through self-fertility parents with medium resistance were all of the medium resistance.The mating types A1:A2 was greater than 1:1 in single oospore strains of the progenies,which did not conform to the Mendel's law of inheritance.All single oospore strains of the progenies inherited mitochondrial DNA fragments from only one parent.Sexual recombination of single oospore strains was verified by using two pairs of SSR primers(Pi4B and Pi4G).At the locus of Pi4B and Pi4G in the cross of KS-37 and KS-25,the separation frequencies of allele were 19:12 and 14:17,respectively.They produced two new genotype strains.This study could provide a basis for formulating disease control strategies.

Primed Expression of Defense-Related Genes by Streptomyces cameroonensis-Based Bioformulation (SCaB) on Cocoa Seedlings in a Nursery Challenged with Phytophthora megakarya

A Streptomyces cameroonensis based bioformulation (SCaB) has been developed and shown to be stable and effective in controlling the early proliferation of P. megakarya and promoting the growth of cocoa seedlings in nursery. This study was carried out to explore the molecular mechanisms associated with the interaction of SCaB, cocoa seedlings, and the pathogen during the early stages of seedling growth in the nursery. For this purpose, seedling treatment with 10% W/W SCaB under greenhouse conditions evaluated SCaB’s capacity to stimulate the defense mechanisms in cocoa. Agronomic growth parameters and the level of induction of defense-associated compounds were analyzed. Real-time (rt) PCR was used to assess the level of expression of defense genes. Here, we showed that the application of SCaB as a seedling treatment enhanced the growth of cocoa seedlings in the nursery by an average of 15.6% after 30 days of growth and led to an average reduction in disease severity of 64% when challenged with P. megakarya. The latter led to an increased synthesis of total phenolic compounds, flavonoids, chitinases, peroxidases, and β-1,3-glucanases and an induced up-regulation of TcChiB, TcGlu-1, TcPer-1, and TcMYBPA genes. This research provides a basis for the optimization of beneficial microorganisms as a viable alternative to chemical fungicides used in disease suppression.

影响大豆疫霉菌Phytophthora sojae卵孢子生活力和萌发的因素

本研究的目的是寻找一种能够促使大豆疫霉菌卵孢子在短时间内大量萌发的方法。结果表明,卵孢子菌龄、预处理温度、化学物质及其浓度在某种程度上均影响大豆疫霉菌卵孢子的生活力。胡萝卜琼脂平板上24℃密封培养条件下,30d菌龄的卵孢子中只有10.56%处于萌动状态,但经0.4%的KMnO4处理20min或35℃处理5d后,萌动率分别提高到58.49%和83.55%,但并不萌发。以3mL大豆感病品种Sloan的根系分泌物为培养液,26℃黑暗或光照培养7d即可获得80%以上的卵孢子萌发率。

不同浓度臭氧水对致病疫霉菌Phytophthora infestans孢子萌发抑制作用初报

采用不同浓度臭氧水对致病疫霉菌Phytophthora infestans(Mont.)de Bary孢子囊萌发进行了试验,结果表明:臭氧水处理对孢子囊萌发的影响与臭氧水浓度密切相关,以9 mg/kg臭氧水处理1 min可以抑制95%以上孢子囊萌发,以18 mg/kg臭氧水处理1 min则100%抑制孢子囊萌发。无论在高浓度还是在低浓度条件下,处理时间1 min或2 min对孢子囊萌发没有产生显著影响,杀菌作用几乎是瞬间完成的。臭氧水处理孢子囊后导致孢子囊形态发生变化,这种变化随时间延长变得更加明显。鉴于高浓度臭氧水对植物本身不产生毒害作用,因此,高浓度臭氧水在控制晚疫病方面显示出广阔的应用前景。

Distribution and Virulence Diversity of Phytophthora sojae in China

By investigating occurrence of Phytophthora root rot in fields and isolating P.sojae fromdiseased plants and soils, the distribution of P.sojae in China was surveyed. In addition tonortheast region, P.sojae existed in Huanghe-Huaihe basin and Yangtze basin too. Eighty- threeisolates of P.sojae isolated from different areas were identified on virulence using 13differential soybean cultivars, abundant virulence diversity was found in P.sojae. The greaterdiversity in virulence of P.sojae was in isolates from soil than from plants. And the greatestvirulence diversity of P.sojae was found in Yangtze basin.

烟草黑胫病原菌(Phytophthora parasitica Var·nicotianae)生理生化特性的研究

本文主要介绍了用人工合成培养基测定烟草黑胫病原菌的致死温度、最适生长的pH值和能够生长的pH值范围的方法及结果。对黄河等“适宜于马铃薯晚疫病菌的一种液体合成培养基”,在配方和实验方法上做了一些改进。通过实验,进一步证实了该菌在营养生长过程中钙素的重要性和三羧酸循环(TCA)中有机酸的重要性;该菌的营养生长并不需要较复杂的营养条件。

Resistance Evaluation of Soybean Germplasm from Huanghuai Region to Phytophthora Root Rot

The aim of the study was to establish a set of differential strains and to identify soybean resistant genes to Phytophthora root rot and then to apply those strains for analysis of the resistant genes Rps1a,Rps1c,and Rps1k that soybean cultivars or lines may carry.Virulence formula of 125 Phytophthora sojae isolates were determined using the hypocotyls inoculation technique,the strains,which includ 6 isolates with different virulence formulas,were applied to identify the resistance of 55 soybean cultivars or lines and resistant genes were analyzed using the gene postulating procedure.Eighteen reaction types occurred in 55 cultivars or lines and results of gene postulation indicated that 2 cultivars or lines probably carried gene Rps1c and no cultivar may carry genes Rps1a or Rps1k.A few of soybean cultivars or lines from Huanghuai Region carry Rps genes Rps1a,Rps1c and Rps1k and tend to infect by P.sojae,so resistant cultivars or lines need to be bred and popularized actively.

大豆疫霉菌(Phytophthora sojae)增强型绿色荧光蛋白遗传转化载体的构建

载体的构建是建立遗传转化体系的基础。以真核表达载体pcDNA3.1(-)/hygro为基本骨架,构建大豆疫霉菌遗传转化载体,通过限制性内切酶酶切、去磷酸化、连接等基因重组技术,将增强型绿色荧光蛋白(Enhanced Green Fluorescent Protein,EGFP)基因和来自莴苣霜霉菌(Bremia lactucae)的启动子(ham34)、终止子重组到真核表达载体pcDNA3.1(-)/hygro中,经大肠杆菌转化后对转化子进行了酶切验证,为大豆疫霉菌遗传转化体系的建立提供载体。

Phytophthora α1性信息素C(9)～C(16)片段的合成

以甾体皂甙元氧化降解废弃物（R）-4-甲基-5-羟基戊酸甲酯为原料，经包括酯的格氏加成反应、烯烃的臭氧化反应和环氧化合物的亲核加成等六步反应，以60．5％的总收率合成得到了Phytophthora α1性信息素的C（9）-C（16）片段4。

柑桔脚腐病菌Phytophthora parasitica杀菌剂的室内筛选

柑桔脚腐病是为害柑桔主干基部的病害。采用菌丝生长速率法对柑桔脚腐病菌寄生疫霉Phytophthoraparasitica进行了21种农药的室内毒力测定。结果表明，各药剂对寄生疫霉菌丝的生长均有抑制作用，并且其抑制率与药剂浓度呈正相关。其中，毒力作用最强的是50％烯酰吗啉水分散粒剂，EC50为0．2598μg／mL；其次是60％唑醚·代森联水分散剂、2％春雷霉素水乳剂、70％丙森锌可湿性粉剂、10％多抗霉素B可湿性粉剂、50％多·锰锌可湿性粉剂和50％醚菌酯水分散粒剂，EC5。在1．0～7．7μg／mL之间；再次是65％代森锌可湿性粉剂、10％井冈霉素水乳剂、10％苯醚甲环唑水分散粒剂、40％腈菌唑水分散粒剂、43％戊唑醇悬浮剂、25％丙环唑乳油、3％中生菌素可湿性粉剂、68％碱式硫酸铜水分散粒剂、40％氟硅唑乳油和12．5％烯唑醇可湿性粉剂，EC50在18．0～69．0μg／mL之间；较差的是50％敌克松可湿性粉剂、50％异茵脲可湿性粉剂、70％甲基硫菌灵可湿性粉剂和50％甲基硫菌灵悬浮剂，EC50在329．0μg／mL以上，尤其甲基硫茵灵70％可湿性粉剂和50％悬浮剂的EC50分别高达979．1665和1713．8330μg／mL，不宜推荐继续用于柑桔脚腐病的防治。

对马铃薯晚疫病菌(Phytophthora infestans)有杀菌毒性的中草药的筛选(英文)

将来源于 44科的 88种中草药等植物材料的提取物稀释 5 0 0倍后 ,与马铃薯晚疫病菌 (Phytophthorainfestans)的孢子囊悬浮液混合。有 31种材料的提取物在该浓度下表现了对马铃薯晚疫病菌的游动孢子囊间接萌发的完全抑制作用 ,有 46种提取物也表现了不同程度的抑制作用 ,另有 11种提取物在该浓度下没有表现抑制作用。在抑制菌丝生长作用的试验中 ,植物提取物用黑麦培养基稀释 2 0 0倍 ,然后倒皿 ,在 8.5cm直径的培养皿中央放一马铃薯晚疫病菌菌片 ,16℃下培养 ,15d后测量菌落直径大小。结果表明 ,在供试的 83种提取物中 ,在稀释 2 0 0倍浓度下 ,有 32种提取物表现了对菌丝生长的完全抑制作用 ,2 4种表现了比较强的抑制作用 ,而有 2 7种提取物没有表现对菌丝生长的抑制作用 ,甚至还表现了对菌丝生长的促进作用。同时 ,还有

云南省发现马铃薯晚疫病菌(Phytophthora infestans)A2交配型

将一批分离自楚雄、大理、昆明、曲靖、宣威等马铃薯产区的晚疫病菌在利马豆 Ｖ８ 琼脂培养基上与 Ａ１ 交配型标准菌株进行交配型测定， ４７ 个菌株中出现了１０ 个 Ａ２ 交配型菌株。亲和性菌株交配时产生大量具有典型特征的有性结构。对卵孢子、穿雄生的藏卵器以及雄器的形态特征和大小进行了描述。这是云南马铃薯晚疫病菌中存在 Ａ２ 交配型菌株的首次报道。

影响大豆疫霉菌(Phytophthora sojae)游动孢子产生的条件

间歇性地给菌丝块换水可以诱导菌丝产生孢子囊 ,进而释放游动孢子。挑取 5～ 8块直径为 8mm于利马豆或 V8汁平板上培养 4～ 8d的菌块 ,置于直径 7cm的培养皿内 ,加入蒸馏水正好没过菌块表面 ,每 30 min换水一次 ,换水 4次后加入 15 ml Petri培养液 ,2 5℃、黑暗条件下培养 18～ 2 0 h,可诱发菌块大量产孢。

致病疫霉(Phytophthora infestans)对杀菌剂抗药性研究进展

综述了致病疫霉 (Phytophthorainfestans)对内吸性杀菌剂甲霜灵、霜脲氰和保护性杀菌剂代森锰锌和百菌清的抗性研究进展 ,总结了当前用于防治晚疫病的药剂种类并提出了抗性治理策略。对于致病疫霉抗性遗传研究和抗性治理及药剂防治都具有一定的参考价值。

棉铃疫病菌(Phytophthora boeh meriae)对甲霜灵的抗性遗传研究

本文在实验室条件下 ,经药物直接诱变 ,筛选获得棉铃疫病菌 (PhytophthoraboehmeriaeSawada)抗甲霜灵突变株 ,研究了其抗药性性状的遗传。结果表明 ,棉铃疫病菌易对甲霜灵产生抗性 ,抗性菌株对甲霜灵的抗性水平可高达其敏感亲本的 5 16 1 3倍以上 ;部分抗性菌株的抗药性性状在无性及有性单孢后代均可稳定遗传 ,另有部分抗性菌株的抗性性状在无性单孢后代出现分离甚至完全丧失。初步认为 。

重庆地区马铃薯晚疫病菌(Phytophthora in festans)对甲霜灵抗性及抗性水平测定

20 0 1年从北碚、云阳、开县、万州、巫溪和忠县等地采集马铃薯晚疫病病叶 ,共分离得 94株致病疫霉。用生长速率法测定其对甲霜灵的抗性和抗性水平 ,结果表明 :2 0 2 %的菌株表现为抗性 ,11 7%的菌株表现为中抗 ,6 8 1%的菌株表现为敏感 ;以菌株PBB 110 2为敏感对照 ,所测定的 2株抗性菌株的抗性水平达 10 6倍以上 ,各地菌株抗性表现与菌株来源地的施药水平密切相关 。

马铃薯晚疫病菌(Phytophthora infestans)A2交配型的研究进展

近年来，关于马铃薯晚疫病菌（Ｐｈｙｔｏｐｈｔｈｏｒａ ｉｎｆｅｓｔａｎｓ）Ａ２交配型的研究有很大进展。本文就马铃薯晚疫病菌Ａ２交配型的鉴定方法、在世界各国的分布、出现的原因、出现的后果以及卵孢子的生物学特性进行了综合评述，指出卵孢子作为新的初侵染来源在该病害流行中起着很重要的作用。