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.

Cloning of Potato POTHR-1 Gene and Its Expression in Response to Infection by Phytophthora infestans and Other Abiotic Stimuli

A complete cDNA of potato Phytophthora infestans-induced hypersensitive response-related protein gene (POTHR-1) was cloned using rapid amplification of cDNA ends (RACE) strategy according to a fragment sequence which we had cloned using suppression subtractive hybridization (SSH) technique. The potato POTHR-1 gene encodes a protein of 225 amino acids, which shares 81% identity with tobacco hin1 gene-enoded protein (harpin-induced protein). Southern blot revealed that there are two to three copies of POTHR-1 in potato genome. The POTHR-1 gene expression in potato leaves showed that its transcripts accumulated remarkably in leaves after 36 h inoculation with P. infestans. Mechanical wounding and jasmonic acid (JA) could induce the POTHR-1 gene expression and osmotic stress just induce a slight accumulation of POTHR-1 gene mRNA, while salicylic acid (SA) had no detectable function on the induction accumulation of POTHR-1 gene transcripts. The potato POTHR-1 gene may preferentially associate with hypersensitive response (HR) or biotic cell death during interaction between host and pathogen.

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

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。

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。

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。

河北省马铃薯晚疫病菌(Phytophthora infestans)A2交配型的分布

对 1996— 1997年采自河北省马铃薯主产区的 2 8个马铃薯晚疫病菌的菌株在白云豆 -V8蔬菜汁培养基上进行了交配型测定。结果发现 ,在 2 8个菌株中 ,18个菌株为A1交配型 ,占被测总菌株数的 6 4.3% ;10个菌株为A2交配型 ,占被测总菌株数的 35 .7% ,其中 9个菌株采自承德市围场县 ,1个菌株采自张家口市康保县。说明在河北省的 2个马铃薯主产区均存在A2交配型 ,且在同一块田中同时存在A1和A2交配型。同时还发现该病菌单位面积产生卵孢子的数量差异很大 ,为 10～ 2 30 0个·cm-2 。并对藏卵器、雄器、卵孢子的大小、颜色。

马铃薯Y病毒(PVY)对晚疫病(Phytophthora infestans)的影响

在温室条件下，以脱毒马铃薯为试材，研究了PVY对晚疫病的影响。结果表明：PVY汁液接种脱毒马铃薯28d后，用晚疫病菌接种，其孢子囊悬浮液浓度为1．0×104个·mL-1时，PVY对晚疫病的抑制作用最明显；马铃薯植株体内PVY的浓度与晚疫病的发病率、病斑大小及病情指数呈负相关。说明马铃薯感染PVY后诱导了植株对晚疫病的抗性，不同因子影响降低了马铃薯感Y病毒叶片对晚疫病菌的感病性。

番茄晚疫病菌(Phytophthora infestans)对甲霜灵的抗性测定及治理

2 0 0 0～ 2 0 0 1年连续 3季从壁山、沙坝坝蔬菜基地采集番茄晚疫病病叶和病果 ,共分离得 80株晚疫病菌。用生长速率法测定其对甲霜灵的抗性和抗性水平 ,结果有 75 0 %的菌株表现为抗性 ,13 8%的菌株表现为中抗 ,11 2 %的菌株表现为敏感。以菌株TBS 2 131为敏感对照 ,所测定的 4株抗性菌株的抗性水平达 5× 10 4倍以上。此结果表明当地晚疫病菌抗性菌株已占优势 ,并且抗性水平已很高。同时有针对性地提出了防治番茄晚疫病的用药策略。

福建致病疫霉(Phytophthora infestans)群体遗传多样性分析

从150条RAPD随机引物中筛选出多态性引物12条,对分离自福建省10个不同市(县)的番茄或马铃薯晚疫病标样中的63个致病疫霉菌株进行遗传多样性分析,共产生92条RAPD条带,其中85条为多态性条带,多态检测率为92.4%。利用NTSYSpc Version 2.1软件对供试菌株间的遗传距离进行聚类分析并构建系统树状图,供试63个菌株被划分为6个遗传聚类组,RAPD分组与菌株的地理来源、寄主均无明显相关性。聚类分析结果表明,福建省不同地区的致病疫霉菌株整体亲缘关系相近,但各菌株间存在遗传差异,病原菌随病果运输迁移及A2交配型的存在可能是导致这种现象的原因。

马铃薯晚疫病(Phytophthora infestans)(Mont.) de Bary)的流行和防治研究(英文)

1997年做了田间试验用来评价影响马铃薯晚疫病流行的关键天气条件。在Reckenholz做了 2个试验研究晚疫病的潜伏期和侵染速率。结果表明 ,当累计有效积温达到 2 34 6 5℃·h时 ,孢子囊开始在马铃薯叶片出现。温度是影响晚疫病流行的重要因子。病害侵染的重要条件是温度超过 10℃并且在连续 6h内空气相对湿度大于 90 %。降雨在病害传播中发挥了重要作用。

黑龙江省发现马铃薯晚疫病菌(Phytophthora infestans)A2交配型

对2005-2012年间采集自黑龙江省哈尔滨、望奎、漠河、塔河、呼玛、加格达奇、嫩江、克山、甘南、鹤岗、肇东、林口12个市县的133个马铃薯晚疫病菌株进行了交配型鉴定。结果表明,采集自2005-2010年间的51个菌株均为A1交配型,未发现A2交配型;采集自2011年的52个菌株中12个为A2交配型,占23.08%;2012年鉴定的30个菌株中9个为A2交配型,占30%。这是自2004年朱杰华报道发现一株A2交配型六年后,黑龙江省首次确认在甘南、哈尔滨、肇东发现马铃薯晚疫病菌A2交配型。

Exogenously applied methyl Jasmonate induces early defense related genes in response to Phytophthora infestans infection in potato plants

In order to elucidate the contributions of JA in orchestrating disease resistance in potato plants,the potato genotype‘SD20’,which exhibits strong resistance against the highly virulent Phytophthora infestans isolate CN152,while infected by the super virulent isolate 2013-18-306,was treated with exogenous JA and then challenged by inoculation with 2013-18-306.The results showed that exogenously applied JA significantly delayed the onset and alleviated the symptoms of late blight,indicating exogenous JA could induce resistance to P.infestans in the early biotrophic stage of infection in‘SD20’plants.To further clarify the role of JA in the early defense response and identify key genes involved in JA signal transduction,gene expression profiling via RNA sequencing(RNA-seq)in‘SD20’plants treated with exogenously applied JA was performed.A total of 2927 differentially expressed genes were specifically induced,the majority encoded transcription factors,protein kinases,secondary metabolites,defense enzymes and disease resistance related proteins.GO functional annotation and KEGG metabolic pathway analysis showed that exogenously applied JA rapidly induced the expression of genes related to immune response regulation,pathogen defense,and other biological processes,and stimulated endogenous JA synthesis and signal transduction,and the overall early pathogen defense response in‘SD20’.These results provide useful information in understanding the JA’s function involved in pathogen defense responses and a theoretical basis for the application of JA in potato production.

Sensitivities of Phytophthora infestans to Metalaxyl, Cymoxanil, and Dimethomorph

The isolates of Phytophthora infestans on tomato in the Guangxi Zhuang Autonomous Region, China, were determined for the sensitivities to metalaxyl, cymoxanil and dimethomorph to give the basic information for integrating disease management. Sensitivities were tested by measuring the radial growth on agar medium amended with fungicide, compared with the floating-leaf-disk method. 239 isolates were collected from eight tomato growing areas during 2000-2006. The testing results indicated that the frequencies of sensitive, intermediate, and resistant isolates to metalaxyl were 42.26, 35.98, and 23.53%, respectively. Variations in sensitivities amongst isolates from different areas or different years were very high for metalaxyl. All isolates from Tianlin and Wuxuan were sensitive to metalaxyl, but the metalaxyl-resistant isolates predominated in Tianyang, with the frequency of 51.35%. The EC50 values of certain isolates from Tianyang were higher than 500 μg·mL^-1 and their resistance levels were over 100 000 folds. Cymoxanil has been used for nearly 10 years in Guangxi, and dimethomorph has been used for 5-6 years. However, there was no decrease in sensitivity of P. infestans populations and the sensitivities of the pathogen were nearly normally distributed. Hence, their mean ECs0 value [cymoxanil （0.1647 ±0.0255） μg·mL^-1, dimethomorph （0.0970 ± 0.0052） μg·mL^-1 could be used as the baseline sensitivities for monitoring the field resistance development. The comparison with the floating-leaf-disk method indicates that both the techniques provided equivalent results. These studies suggested that metalaxyl can be continuously applied in Tianlin, Wuxuan, and Nanning due to the resistant isolates that have not been found, while for those areas with resistant isolate, the use of metalaxyl should be reduced or alternated, and cymoxanil or dimethomorph was recommended for controlling late blight disease of tomato.

Race Structure and Distribution of Phytophthora infestans in the Investigated Areas of China

Ninety isolates collected from five different provinces and cities (Hebei, Yunan, Sichuan, Chongqing, Inner Mongolia ) during 1997 - 1998 were tested with potato clones possessed 8 dominant mono-genes R1, R3, R4, R6, R7, R9, R10, R11 and the combination of R1-R4 of the international late blight differential host. It concluded that: (1) in the 90 isolates tested 21 different races were detected, of which the 1.3.4. 7. 9. 10. 11 was very common with frequency of 32. 2%, followed by 1. 3. 4. 6. 7. 9. 10. 11 and 3.4.7. 9. 11 with frequency of 10.0%; (2) all tested resistant genes were compatible to the virulent gene of isolates of Phytophthora infestans assayed, which indicated that the virulent genes were very common in the tested population of Phytophthora infestans.

Study on the Relationship Betweenthe Toxin of Phytophthora infestans(Mont.) de Bary and Resistance of Potato

Plant pathogenic fungi produce mycotoxins which may lead host plants to produce disease symptoms and may have a significant positive role in the course of disease development.The putative Phytophthora infestans toxins were prepared by culturing in liquid medium（60 g rye and 10% tomato juice L-1） for 1 mon at 17℃,filtering through four layers of cheesecloth and being precipitated by ammonium sulfate.The resulted putative toxin solutions were used to study the effects on 3 potato varieties（both leaf and tuber tissues）.The results show that potato leaves and tubers exhibit symptoms similar to the late blight resulted from P.infestans infection.Potato varieties reacting differentially to both the toxin dilutions and toxins produced by different P.infestans isolates suggested the presence of toxin-mediated specificities between potato and P.infestans.Potato leaf and tuber tissues have different and contrary reactions to the toxin.Toxin-mediated specificities are likely present between potato and P.infestans.

Potato late blight caused by Phytophthora infestans:From molecular interactions to integrated management strategies

Over 170 years after the infamous Irish Potato Famine,potato late blight(PLB)caused by Phytophthora infestans remains the single most devastating disease of global potato production,causing up to 10 billion USD in yield loss and management costs.Through decades of research,growers and agronomists in the field as well as laboratory scientists have made significant progress in understanding the molecular pathogenesis process of this critical pathosystem and effective management strategies to control PLB.Yet,the need to feed an ever-increasing global population under changing climate demands continued improvement in efficient and sustainable PLB management schemes that can be implemented across a broad economic spectrum.In this review,we briefly summarize the current understanding of the molecular interaction between P.infestans and its host plants,highlight the current integrated pest management strategy to control PLB on local and continental scales,and discuss the potential of further improvement of sustainable PLB control through genetic enhancement of crop resistance and emerging crop protection technologies.

A Preliminary Investigation on Phenotypic Characteristics of Phytophthora infestans from Guizhou Province

Abstract [ Objective ] This study aimed to investigate the phenotypic characteristics of Phytophthora infestans from Guizhou Province. The metalaxyl resistance, mating type and isozyme genotype of 292 P. infestans strains isolated from Guizhou Province were analyzed. [ Result] Metalaxyl-resistant P. infestans strains were found in different areas of Guizhou Province. Resistant, moderately resistant and susceptible strains accounted for 35.62% , 33.90% and 30.48% , re- spectively. Both mating types A1 and A2 were found, which accounted for 65.38% and 34.62%, respectively. P. infestans strains isolated from Guizhou Province mainly belonged to Gpi genotypes 100/100 and 100/100/111, accounting for 50.68% and 43.84%, respectively. [ Conclusion] This study provides the theoretical basis for the prevention and control of potato late blight in Guizhou Province.

黑龙江省马铃薯晚疫病菌(Phytophthora infestans)群体动态分析

2019~2020年在黑龙江省11个市县采集并分离262株马铃薯晚疫病菌(Phytophthora infestans),并对其作甲霜灵抗药性、交配型、mtDNA单倍型和SSR基因型测定。交配型测定结果表明,A1型、A2型和SF型菌株分别占所分离菌株总数81.3%、11.1%和7.6%。甲霜灵抗药性测定结果显示,甲霜灵高抗性菌株、中抗性菌株和敏感性菌株占比分别为55%、27.1%和17.9%。线粒体DNA单倍型测定中,共检测出Ia和IIa两种mtDNA单倍型占比分别为9.2%、90.8%。利用11对引物对采集的马铃薯晚疫病菌作SSR基因型分析,共检测出39种SSR基因型,其中H-11为优势基因型,分离频率为18.32%,其次为H-28,分离频率为13.74%。在11对SSR引物中,SSR2的Nei's基因多样性为0.4985,均高于其他等位基因Nei's基因多样性。2019年检测出28种SSR基因型,2020年检测出35种SSR基因型,基因型H-9、H-18、H-26、H-27为2019年特有SSR基因型,基因型H-29~H-39为2020年特有SSR基因型;望奎县检出7种基因型,较其他市县基因型丰富。

以Ypt1基因为靶标的致病疫霉菌Phytophthora infestans的分子检测

三磷酸鸟苷(GTP)结合蛋白基因(Ypt1)是一个与原癌基因Ras(Rat sarcoma)相关的基因,在酵母中,该基因编码一个与Ras相关GTP结合蛋白。为了研究以Ypt1基因为分子靶标的致病疫霉菌(P.infestans)检测技术,比较了30种卵菌Ypt1基因的序列,以该序列为靶标设计了1对针对P.infestans的特异性PCR引物Pi1/Pi2。试验结果表明,在供试的55种不同疫霉菌和真菌的144个菌株中,利用这1对引物只能从P.infestans基因组DNA中分别扩增出1条分子量为369 bp的特异性条带,这1对引物的检测灵敏度为100 pg。以疫霉菌Ypt1通用引物Yph1F/Yph2R结合这1对特异引物进行套式PCR扩增,使引物Pi1/Pi2的检测灵敏度提高了10倍,检测到10 pg的基因组DNA。通过套式PCR,引物Pi1/Pi2对游动孢子和卵孢子的检测灵敏度分别为3个游动孢子和1个卵孢子;以Pi1/Pi2引物,分别采用单轮PCR和套式PCR可检测马铃薯发病组织和病田土壤的致病疫霉。以上结果证明Ypt1基因适合作为疫霉菌分子检测靶标。采用以这1对特异引物建立的以PCR技术为基础的分子检测方法,可对田间土壤和发病植物组织中的P.infestans进行快速、灵敏的检测。