Evaluation of phytophthora root rot-resistant <i>Capsicum annuum</i>accessions for resistance to phytophthora foliar blight and phytophthora stem blight

A mixture of six Georgia isolates of Phytophthora capsici (Leon.), the causal agent of phytophthora blight, were used for greenhouse mass screening of over 700 accessions of Capsicum annuum for both stem blight and foliar blight. From this screening, it was determined that resistance to both forms of the disease were relatively common in the germplasm, but resistance to one form of the disease was not strongly correlated to resistance to the other form. Ten accessions previously shown to possess root rot resistance were tested for resistance to stem rot and leaf blight, and were found to also be highly resistant to these forms of the disease. It appears that single accessions have resistance to foliar, stem and root rot caused by P. capsici, which may simplify breeding for resistance to all three forms of the disease.

Molecular Detection of Phytophthora colocasiae of Taro Leaf Blight Based on PCR

The present PCR assay was conducted to develop rapid and sensitive detection of Phytophthora colocasiae,in order to provide a robust and reliable tool for healthy seedling production of taro and limiting the transmission and spread of the causal organism of taro leaf blight in taro planting regions.The samples were used to extract total DNA and to be detected by PCR with P.colocasiae specific primer pairs PCSP-RL F/PCSP-RL R and PCSP-T F/PCSP-T R,respectively.Distinct fragments of about 200 bp and 240 bp were amplified by PCR using primers PCSP-RL F/PCSP-RL R and PCSP-T F/PCSP-T R,respectively.The analysis of the nucleotide sequence of the PCR products were found to be 99% identical to sequence of RAS-related protein (Ypt1) and phospho-ribosylanthranilate isomerase (TRP1) in P.colocasiae,respectively.It is concluded that rapid and sensitive developed PCR assay for detection of P.colocasiae could be used in routine diagnosis and aid in management practices to mitigate taro leaf blight.

半夏防御酶系对Fusarium oxysporum和Phytophthora parasitica侵染的动态反应

尖孢镰刀菌(Fusarium oxysporum Schlecht)和寄生疫霉(Phytophthora parasitica Dastur)分别为引起半夏块茎腐烂病和疫病的病原,为探索半夏在受到这2种病原侵染时的生理生化反应,采用室内盆栽方法,研究超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、多酚氧化酶(PPO)、苯丙氨酸解氨酶(PAL)5种寄主防御酶活性在块茎腐烂病和疫病发生过程中的变化趋势。结果表明,半夏在接种2种病原菌后,分别于第2天和第3天出现发病症状,第5天病情指数分别高达70.3、70.6;SOD活性都于接种后第1天达到高峰,POD活性都于接种后第3天达到高峰,CAT活性都于接种后第2天达到高峰,PAL活性分别于接种后第2天和第3天达到高峰,而PPO活性分别于接种后第3天和第4天有小幅上升。初步表明,在寄主显症之前或发病初期酶活性达到高峰的SOD、POD、CAT、PAL在半夏抗病生理机制中起着重要作用,在半夏抗病种质筛选时需要重点关注。

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。

南瓜疫病菌(Phytophthora capsici)的生物学特性初探

以南瓜疫病菌株ＰＣ－１为研究对象，分析其生物学特性。结果表明，不同培养基对菌丝生长影响不同，菌丝在葫萝卜琼脂（ＣＡ）培养基上生长要好于燕麦片琼脂（ＯＭＡ）培养基。孢子囊的产生需要有水分，同时也受温度、光照、培养基及菌龄的影响。在一定温度范围内，温度升高，孢子囊产生的速度加快且数量多，光照有利于孢子囊的产生，１０℃以下无论有无光照均不产生孢子囊。

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。

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。

辣椒抗疫病种质资源筛选

由辣椒疫霉菌(Phytophthora capsici)侵染引起的辣椒疫病是一种危害严重的土传病害,为了筛选抗辣椒疫病的辣椒种质资源,试验以31份辣椒种质资源为材料,在温室栽培条件下,采用灌根法接种辣椒疫霉菌,鉴定各材料对辣椒疫病的抗性级别,鉴定结果为:不同辣椒种质资源材料之间的抗性有明显差异,病情指数在0~94之间;表现为高抗材料7份、抗病材料2份、中抗材料9份、感病材料10份。

菌糠水提液对马铃薯致病疫霉的抑制机理

菌糠是菌菇生产后残留的物质,含有丰富的无机盐和有机质等成分。利用热水浸提法制备香菇菌糠水提液(water extract from spent mushroom substrate,WESMS),通过紫外分光光度计和Zeta电位及粒径仪对其紫外吸收情况、表面电荷和水中分散粒径进行表征,采用平板渗透法及十字交叉测量直径法计算WESMS对致病疫霉的抑制率,利用光学显微镜和扫描电镜观察病原菌细胞形态的损伤程度,并采用琼脂糖凝胶电泳法分析WESMS对致病疫霉DNA的影响。结果表明,WESMS在紫外线A(UVA,315~400 nm)、B(UVB,280~315 nm)和C(UVC,100~280 nm)波段均有吸收,在水中的分散粒径为3649.27 nm。抑菌试验表明,WESMS对病原菌的生长具有抑制作用,随着提取液体积百分浓度的增加,抑制效果更明显,在高体积百分浓度(6.25%WESMS)作用下对病原菌的抑制率近100%。经WESMS处理后病原菌的菌丝更加扭曲、扁平,且褶皱明显增多,表明WESMS可对细胞造成明显破坏;WESMS处理组的DNA条带亮度暗于对照组,损伤程度与WESMS体积百分浓度呈正相关。研究结果为菌糠的资源化利用及其对马铃薯晚疫病的有效防治提供科学依据和技术支撑。

Inheritance Analysis and Identification of SSR Markers Linked to Late Blight Resistant Gene in Tomato

Late blight caused by Phytophthora infestans is the most serious disease of tomato production in China. Studies on the genetics of resistance and identification of molecular markers are very useful for breeding late blight resistant varieties. The objective of this paper was to study the inheritance of late blight resistance and identify simple sequence repeat （SSR） markers associated with resistance allele in tomato （Lycopersicon esculentum Mill）. The results came from an F2 progeny of 241 plants derived from a cross between 5~ inbred line that is susceptible to late blight and a resistant accession CLN2037E. The late blight responses of F2 plants were tested by artificially inoculation of detached-leaflets in plate and natural infection assayed under greenhouse conditions. Both methods showed that the resistance is dominant and inherited as monogenic trait. Genetic mapping and linkage analysis showed that the late blight resistance gene Ph-ROL was located on chromosome 9 with a genetic distance of 5.7 cM to the SSR marker TOM236.

DNA Markers for Selection of Late Blight Resistant Potato Breeding Lines

Potato late blight, caused by the oomycete Phytophthora infestans, is one of the most devastating diseases in the agricultural sector around the world. Many genes (R genes) conferring resistance to late blight have been identified in various potato species and most of these R genes have been used in potato breeding. The aim of this study was to develop and validate PCR-based assays for the R genes Rpi-blb1, Rpi-blb2, Rpi-blb3 and Rpi-bt1, to distinguish between late blight resistant and late blight susceptible potato progeny in the given breeding background. A total of 100 breeding progeny were screened for the presence of these R genes and tested for resistance against P. infestans mating type A2, genotype US-8 strain, using detached leaf and tuber rot assays. PCR products for the Rpi-blb1 and Rpi-bt1 resistance genes were identified in the resistant progeny but were absent in the susceptible ones;therefore these PCR assays could differentiate between late blight resistant and susceptible plants. Genotypic data from the DNA markers derived from the Rpi-blb1 and Rpi-bt1 genes was found to correlate with the phenotypic data for foliar late blight but not with data for tuber rot. Our results demonstrate that markers derived from these two R genes could be useful for marker-assisted selection (MAS) for foliar late blight resistance in potato breeding programs.

Molecular Markers Associated with <i>Ph</i>-3 Gene Conferring Late Blight Resistance in Tomato

Late blight (LB), caused by the oomycete Phytophthora infestans, is one of the most devastating diseases of tomato. Three major genes Ph-1, Ph-2 and Ph-3 conferring resistance to LB have been identified and mapped to the chromosomes 7, 10 and 9, respectively. However, PCR-based molecular markers associated with these genes are limited. Molecular markers are extremely useful in the screening and selection of tomato lines for the development of LB resistant genotypes. The objective of this study was to identify molecular markers associated with Ph-3 gene conferring LB resistance in tomato. Four co-dominant markers were found to be associated with Ph-3, all of which were sequence characterized amplified region (SCAR) type. Breeding lines and cultivars were inoculated with a field isolate of Phytophthora infestans to collect phenotypic data on disease resistance. Genotypic data from molecular markers associated with Ph-3 were in close agreement with the phenotypic data for the lines tested. With the verification of genotypic data from novel molecular markers in known genotypes supported by phenotypic data, the novel molecular markers may be useful in screening tomato populations aiming to develop LB resistant genotypes or cloning the LB resistant genes.

辣椒疫病研究进展

因辣椒—疫霉菌互作的分子机制解析是抗性育种的基础,本文从辣椒疫霉菌的宿主和辣椒病害症状、疫霉菌致病因子及其致病机制、辣椒疫病抗性相关基因和抗性网络研究等3个方面综述了近年来辣椒—疫霉菌互作机制的研究进展,以期为进一步深入解析其分子机制提供理论参考。

致病疫霉对烯酰吗啉和双炔酰菌胺的敏感性动态监测及马铃薯晚疫病田间防治药剂筛选

为明确马铃薯北方一季作区致病疫霉对烯酰吗啉和双炔酰菌胺的敏感性时空动态及常用药剂对马铃薯晚疫病的田间防效,采用菌丝生长速率法测定了2011—2019年采自河北、内蒙古和吉林3省(区)马铃薯主产区的922个致病疫霉菌株对烯酰吗啉和双炔酰菌胺的敏感性,采用茎叶喷雾法于2018年和2019年评估了烯酰吗啉和双炔酰菌胺等7种杀菌剂在推荐剂量下对马铃薯晚疫病的田间防效。结果表明:在时间上,不同年份采集的922株致病疫霉对烯酰吗啉的抗性频率和抗性指数分别为25.71%~100%和0.31~0.50;890株致病疫霉对双炔酰菌胺的抗性频率为0~1.43%,仅于2013年检测到抗性菌株,历年抗性指数均为0.25。在地域上,3省(区)致病疫霉菌株对烯酰吗啉的抗性频率和抗性指数分别为57.19%~66.56%和0.39~0.42;对双炔酰菌胺的抗性频率为0~0.36%,抗性指数均为0.25。田间药效试验结果显示:50%烯酰吗啉可湿性粉剂(有效成分,下同) 300.0 g/hm^(2)对马铃薯晚疫病的防治效果(83.3%~85.6%)高于23.4%双炔酰菌胺悬浮剂140.4 g/hm^(2)的防治效果(76.9%~78.6%)和50%氟醚菌酰胺水分散粒剂75.0 g/hm^(2)的防治效果(70.0%~71.4%)。20%霜脲氰悬浮剂162.0 g/hm^(2)、40%氟醚菌酰胺·烯酰吗啉悬浮剂240.0 g/hm^(2)、43%霜脲氰·双炔酰菌胺水分散粒剂290.3 g/hm^(2)和687.5 g/L氟吡菌胺·霜霉威盐酸盐悬浮剂773.4 g/hm^(2)对马铃薯晚疫病的防治效果为79.8%~86.9%。为此,推荐烯酰吗啉单剂或混剂及双炔酰菌胺混剂在河北、内蒙古和吉林3省(区)继续用于马铃薯晚疫病的防治,但是需密切监测致病疫霉对烯酰吗啉和双炔酰菌胺的敏感性变化并注意与不同作用机理的杀菌剂混用或者交替使用。

The disease reactions of heirloom bell pepper “California Wonder” to <i>Phytophthora capsici</i>

Greenhouse studies were performed to determine the reactions of 10 “California Wonder” (Capsicum annuum) accessions to the three forms of Phytophthora blight (root rot, stem blight and foliar blight) caused by Phytophthora capsici. Differences in root rot, stem blight and foliar blight severities among accessions were significant. The accessions consistently differentiated into two groups across the three disease syndromes. Simple sequence repeat (SSR) markers showed variability both within and between accessions of California Wonder. The variability in the responses to the three forms of Phytophthora blight does not warrant its usefulness as a standard susceptible control in studies involving the Capsicum-P. capsici patho-system.

Efficacy of Some Botanical Extracts on the Control of Late Blight Disease in Experimental Potato Field

Late blight caused by Phytophthora infestans (Mont.) De Bary is the most devastating disease of potato. This study was carried out to evaluate the efficacy of ten botanical extracts against the late blight disease incidence and severity in experimental potato field at University of Rajshahi, Bangladesh during 2019-2020. Crude aqueous extract of leaves of Syzygium cumini, Psidium guajava, Eucalyptus globusus, Carica papaya and Lawsonia inermis;fruits of Terminalia bellirica, T. chebula and Piper nigrum;flower buds of Syzygium aromaticum and cloves of Allium sativum were used at 5% (w/v) concentration for evaluation. Out of ten botanicals, Syzygium cumini leaves extract was found most effective in controlling the late blight disease incidence and severity up to 66 DAS (days after sowing) and increased the potato yield by 71.29% compare to untreated control. The efficacy of Lawsonia inermis extract against late blight disease was found promising and increased the potato yield by 48.51%. Other four botanical extracts (Terminalia chebula, Piper nigrum, Syzygium aromaticum and Carica papaya) showed moderate efficacy against the incidence and severity of late blight disease, and increased 30% more potato yield compare to control. These results suggest that botanical extract of Syzygium cumini has a great potential as an alternative of chemical fungicides to control the late blight disease of potato in eco-friendly way.

江西槟榔芋疫病病原菌鉴定及室内药剂筛选

为明确江西省九江市槟榔芋疫病的病原菌并有针对性地对该病害进行防治,本研究采集具有典型芋疫病症状的芋叶片和叶柄对病原菌进行分离纯化,结合形态学观察、致病性测定及基于ITS、Ypt1和β-tubulin基因联合系统发育分析对该病原菌进行鉴定,并测定了其对7种杀菌剂的敏感性。根据病原菌菌落、卵孢子形态等特征初步鉴定为芋疫霉Phytophthora colocasiae,基于多基因联合系统发育分析结果与形态学结果一致,确定该病原菌为芋疫霉。室内药剂筛选结果表明,23.4%双炔酰菌胺SC对菌丝生长抑制效果最好,EC_(50)为0.006μg/mL;96.8%烯酰吗啉TC、0.3%丁子香酚SL、20%氟吗啉WP、500 g/L氟啶胺SC、97%霜脲氰TC对菌丝生长的抑制效果也较好,EC_(50)介于0.094~1.272μg/mL之间,研究结果可为槟榔芋疫病的化学防治提供参考。

马铃薯与致病疫霉互作研究进展与展望

马铃薯是重要的粮食作物,由致病疫霉侵染引发的晚疫病长期严重制约马铃薯产业的健康发展,因此,国内外均将马铃薯晚疫病列为重大病害。目前,抗病品种选育栽培、晚疫病预测预报和化学防治等相结合的晚疫病综合防治手段已得到普遍推广,但晚疫病局部大流行在全世界范围内仍时有发生,给粮食安全和生态安全带来巨大挑战。本文回顾了我国晚疫病的部分研究历史,集中关注致病疫霉与寄主的互作机制领域,梳理了近年来关于致病疫霉侵入机理、效应蛋白毒力功能、病原菌变异规律、马铃薯抗病机理等方面的重要研究结果并展望未来主要的研究方向,以期为晚疫病基础研究和防治技术革新提供参考。

马铃薯晚疫病生防菌研究进展

引起马铃薯晚疫病的致病疫霉(Phytophthora infestans)是马铃薯生产中最具破坏性的病原体之一。生防菌剂(biocontrol agents,BCAs)代替化学杀菌剂防治马铃薯晚疫病是保障马铃薯生产可持续发展的重要措施之一。文章简述了马铃薯晚疫病研究概况和特点,总结了当前生防菌防治马铃薯晚疫病研究的文献。从细菌、真菌和放线菌3个层次系统归纳了致病疫霉生防菌的菌株种属、菌株来源、防治效果、抑菌活性物质及作用机制。分析了生防菌剂在研发和推广应用中面临的挑战性和局限性。提出了未来马铃薯晚疫病生物防治应从增强马铃薯自身防御功能、建立晚疫病预测模型、关注生防菌种群动态和揭示致病疫霉防治机制4个方面进行深入研究。旨在为马铃薯晚疫病生防菌剂的研发和推广应用,及马铃薯绿色产业可持续发展提供参考。

覆施稻壳对大棚黄瓜长势及防控黄瓜疫病的影响

研究覆施不同稻壳量对大棚黄瓜团棵期、盛花期、初果期、盛果期和末果期的长势影响及防控黄瓜疫病的效果。在覆施不同稻壳量后,分别测定黄瓜在每个生长期的土壤温度、棚内相对湿度、株高和茎粗、根系干重和根系活力及黄瓜疫病病情指数等指标。结果表明,与对照相比,覆施25 kg稻壳对大棚黄瓜15 cm处的土壤温度效果最好,且盛果期的温度增幅最快;棚内相对湿度显著下降;黄瓜株高、茎粗、根系干重和根系活力等指标明显提高,黄瓜疫病发生程度显著减轻,以覆施25 kg稻壳处理时黄瓜长势及抗病性最显著,提高了黄瓜产量。该方法成本低、易操作,节时省力,若因地制宜,适量施用,将对保护地黄瓜无公害栽培具有重要作用。