拮抗细菌菌株之间的互作关系及其对生物防治效果的影响

 木文研究了拮抗细菌菌株之间亲和性和生物防治效果之间的关系。试验结果表明:在2个拮抗细菌之间存在多种互作关系。当混合的2个菌株之间互作关系是亲和的,其生防效果有所提高,如亲和性菌株组合B3-3+J-210的防效为47.1%,明显好于单菌株B3-3(35.3%)和J-210(38.7%)的防效。当混合的2个菌株之间互作关系是不亲和的,有的菌株组合生防效果下降,如不亲和性菌株组合C8-8+J-210的防效为23.5%,明显低于单菌株C8-8(52.8%)和J-210(38.7%)的防效;有的菌株组合生防效果提高,如不亲和性菌株组合Cl-2-10+J-210的防效为50.0%,明显好于单菌株Cl-2-10(29.4%)和J-210(38.7%)的防效。因此,在生物防治的实际应用中,首先要了解单个菌株的拮抗活性和优良性能,然后将不同作用机制的拮抗菌株进行混合,并测定菌株之间的互作关系,筛选能产生协同、增效作用的菌株组合,从而保证研制开发的生防菌组合菌剂具有较好的防治效果和生态适应性。     

Piriformospora indica protects barley from root rot caused by Fusarium graminearum

Journal of Plant Diseases and Protection - The beneficial endophytic fungus Piriformospora indica colonizes barley (Hordeum vulgare L.) roots, which results in protection against diseases and...     

Fusarium species from the cassava root rot complex in west Africa

ABSTRACT Fusarium species are a significant component of the set of fungi associated with cassava root rot. Yield losses due to root rot average 0.5 to 1 ton/ha but losses >3 ton/ha, an equivalent of 15 to 20% yield, often occur. This paper reviews previous work on cassava root rot and summarizes a few recent studies on Fusarium species associated with the disease. Our studies in Cameroon showed that 30% of rotted tubers were infected by Fusarium spp. 12 months after planting and represented 25% of all the fungal isolates recovered. Other commonly recovered fungi were Botryodiplodia theobromae and Armillaria spp. Numerous and diverse species of Fusarium were associated with rotted cassava roots in Nigeria and Cameroon. At least 13 distinct amplified fragment length polymorphism (AFLP) groups of Fusarium were distinguishable, each group probably a distinct species, and many of them might represent previously undescribed Fusarium species. The two largest of the AFLP groups correspond to F. oxysporum and F. solani species complex. The distribution of Fusarium spp. varied among countries and among locations within a country, suggesting that germ plasm resistant at one location may not be resistant at another. Fusarium spp. also cause seedling blight of cassava and can be recovered from the stems of infected plants up to 1 m above the ground. Therefore, the pathogen can spread with stems cut as planting material. Fusarium spp. also can colonize Chromolaena odorata, the dominant weed in short fallows, which could further complicate management efforts by serving as an alternative host for strains that colonize cassava.     

一种用玉米拟轮枝镰孢穗腐病病粒制备接种体的简易方法

制备接种体是玉米穗腐病抗性鉴定中的一个重要环节, 本研究提出了一种用玉米拟轮枝镰孢穗腐病病粒制备接种体的简易方法, 即将上年的拟轮枝镰孢穗腐病带菌病粒按一定重量加入无菌水洗脱制成接种体。田间接种试验结果表明, 采用本方法简易制备的接种体接种后可获得与常规制备接种体相当的接种效果, 且在-18℃冻存15 d仍可达到新鲜的常规制备接种体接种后的水平。使用简易制备接种体对33个玉米品种进行了田间穗腐病抗性鉴定, 21个品种表现为感病或高感。与实验室常规培养制备接种体的方法相比, 本制备方法简便易操作, 用时短, 成本低, 无需专业仪器设备, 能够一次制备大量接种体, 可广泛用于玉米种质材料和新品种的拟轮枝镰孢穗腐病田间抗性鉴定及抗性材料筛选等。     

长白山沿脉参类锈腐病菌比较生物学研究

 长白山沿脉是我国人参和西洋参的主要栽培区,长期以来,参根锈腐病一直是该地区参类栽培中最为严重的病害之一。有关参类锈腐病菌具体种类的报道不尽相同,为此,作者分离了长白山沿脉不同地区的12个人参和西洋参锈腐病菌株,在病原形态学研究的基础上,测试比较了各菌株对温度、pH、光照等不同培养条件下的异同,以了解其生物学特性,并辅助形态分类。     

Influence of iron on cylindrocarpon root rot development on ginseng

ABSTRACT Cylindrocarpon root rot, caused by Cylindrocarpon destructans, is an important disease on ginseng (Panax quinquefolius) in Canada. We studied the effects of iron (Fe) on disease severity and pathogen growth. When Hoagland's solution was amended with Fe at 56 and 112 mug/ml compared with 0 mug/ml, disease initiation and final severity on hydroponically maintained ginseng roots was significantly (P<0.0001) enhanced. Under field conditions, wounding of roots with a fine needle followed by application of 0.05% FeNaEDTA to the rhizosphere of treated plants significantly enhanced Cylindrocarpon root rot in 2003 and 2004 compared with unwounded roots with Fe or wounded roots without Fe. Foliar applications of Fe (as FeNaEDTA) to ginseng plants three times during the 2002 and 2003 growing seasons significantly increased Fe levels in root tissues. These roots developed larger lesions following inoculation with C. destructans in vitro. When radioactive Fe ((59)Fe) was applied to the foliage of ginseng plants, it was detected in the secondary phloem and in cortical and epidermal tissues within 1 week. Artificially wounded areas on the roots accumulated more (59)Fe than healthy areas. Diseased tissue also had threefold higher levels of phenolic compounds and Fe compared with adjoining healthy tissues. High-performance liquid chromatography analysis revealed enhanced levels of protocatechuic acid, chlorogenic acid, caffeic acid, ferulic acid, cinnamic acid, phloridizin, and quercetin. Phenolic compounds produced in diseased and wounded tissues sequestered Fe in vitro. The effects of Fe on mycelial growth, conidial germ tube length, and secondary branching of germ tubes of C. destructans were examined in vitro. When grown on Chrome-azurol S medium, Fe also was sequestered by C. destructans through siderophore production, which was visualized as a clearing pigmented zone at the margin of colonies. Mycelial dry weight was significantly increased in glucose/ yeast broth containing Fe at 56 or 112 mug/ml. Conidial germ tube length and secondary branching of hyphae also were enhanced after 8 and 16 h by Fe. Colony growth of C. destructans was not enhanced by Fe, but significantly greater spore production was observed with Fe at 56 and 112 mug/ml compared with no Fe in the medium. Although these levels of Fe had no effect on fungal pectinase enzyme activity, polyphenoloxidase (PPO) activity was significantly (P <0.0001) enhanced. We conclude that Fe enhances Cylindrocarpon root rot through enhanced pathogen growth, sporulation, and PPO enzyme activity. Fe sequestered by phenolic compounds produced in wounded tissues can enhance Fe levels at the site of infection. The pathogen also has the ability to sequester Fe at these sites.     

Fungal endophyte protects Atractylodes lancea from root rot caused by Fusarium oxysporum

Endophytic fungi, which stimulate a variety of defence reactions in host plants without causing visible disease symptoms, have been isolated from almost every plant. However, beneficial interactions between fungal endophytes and pathogens from the same habitat remain largely unknown. An inoculation of Atractylodes lancea plantlets with Gilmaniella sp. AL12 (AL12) prior to infection with Fusarium oxysporum prevented the necrotization of root tissues and plant growth retardation commonly associated with fusarium root rot. Quantification of F. oxysporum infections using real‐time PCR revealed a correlation between root rot symptoms and the relative amount of fungal DNA. Pretreatment with AL12 reduced the accumulation of reactive oxygen species stimulated by F. oxysporum. An in vitro analysis of their interactions under axenic culture conditions showed AL12 could inhibit F. oxysporum growth. Additionally, F. oxysporum infections were shown to decrease salicylic acid (SA) production compared with control plantlets. SA biosynthesis inhibitors, 2‐aminoindan‐2‐phosphonic acid and paclobutrazol, abolished the inhibition of F. oxysporum growth in A. lancea even after inoculation with AL12. The results indicated that the fungal endophyte protected A. lancea not only by direct antibiosis, but also by reversing the F. oxysporum‐mediated suppression of SA production.     

Fusarium crown and root rot of tomatoes in the UK

Fusarium crown and root rot caused by Fusarium oxysporum f. sp. radicis-lycopersici was found in the UK in 1988 and 1989 mainly in rockwool-grown tomato crops. Up to 14% of plants were affected in individual crops. In experiments, leaf and stem symptoms did not appear until the time of first fruit harvest even when the plants were inoculated at planting, first flowers or fruit set. Conidial inoculum at 10⁶ spores/plant applied at seed sowing killed 70–83% of tomato seedlings, whereas similar levels of inoculum applied to young plants caused root and basal stem decay, and eventually death but only after fruit harvest began. Disease incidence and symptom severity increased with inoculum concentration. Experimentally, the disease was more severe in peat- or compost-grown plants than in rockwool. Disease spread was only a few centimetres in 50 days in experimental rockwool-grown plants. All tomato cultivars tested were highly susceptible. Prochloraz-Mn was highly effective against the pathogen in vitro and controlled the disease in the glasshouse, but only when applied preventively. Non-pathogenic Fusarium oxysporum isolates and Trichoderma harzianum also reduced FCRR disease levels.     

Evaluation of antagonistic bacteria for suppression of bacterial ring rot of potato

Bacterial strains with potential for biological control of bacterial ring rot of potato caused byClavibacter michiganensis subsp.sepedonicus were isolated from the surface of potato tubers. Eighty-eight potential biocontrol candidates, selected on the basis ofin vitro antibiosis toC. m. sepedonicus, produced inhibition zones with radii ranging from 0.5 to 16 mm on test plates. All antagonistic isolates were screened in the greenhouse for biocontrol activity on micropropagated potato plantlets root-inoculated withC. m. sepedonicus. Eight strains consistently prevented infection of plantlets but there was no significant correlation between the width of the inhibition zone in thein vitro assay and ring rot suppression in the plant bioassay. Three strains that showed a high level of biological control potential were identified as a saprophytic enteric bacterium (strain 7G), anArthrobacter sp. (strain 16C), and a soil coryneform bacterium (strain 18A). These were tested in a field plot by co-inoculating cut seed potato tubers withC. m. sepedonicus and antagonists. Strains 7G and 18A significantly increased plant stand whereas 16C decreased disease incidence. The relative number of ostensibly ring rot-free progeny tubers was generally greater when antagonists were present.     

Germination of Fusarium oxysporum in root exudates from tomato plants challenged with different Fusarium oxysporum strains

The response of microconidia from pathogenic and non-pathogenic Fusarium oxysporum to root exudates from tomato plants inoculated with different pathogenic and non-pathogenic F. oxysporum strains was studied. Root exudates from non-inoculated tomatoes highly stimulated the microconidial germination of the two tomato pathogens, F. oxysporum f.sp. lycopersici strain Fol 007 and F. oxysporum f.sp. radicis-lycopersici strain Forl 101587. In root exudates from tomato plants challenged with the pathogen Fol 007 the microconidial germination of Fol 007 was increased, whereas in root exudates from plants challenged with Forl 101587 the microconidial germination of Fol 007 was reduced. Root exudates of tomato plants challenged with the non-pathogenic unspecific F. oxysporum strain Fo 135 and the biocontrol strain Fo 47 clearly reduced microconidial germination of the pathogenic strain Forl 101587. Moreover, the microconidial germination rate of the biocontrol strain Fo 47 was increased in the presence of root exudates of tomato plants challenged with the tomato wilt pathogen Fol 007. These results indicate that pathogenic and non-pathogenic F. oxysporum strains alter the root exudation of tomato plants differently and consequently the fungal propagation of pathogenic and non-pathogenic F. oxysporum strains in the rhizosphere is affected differently.     

相关防御酶对人参锈腐病诱导抗性的响应

 为明确水杨酸(SA)对人参抗人参锈腐病的诱导作用,本研究首先采用琼脂平板法测定了SA对人参锈腐病菌(Cylindrocarpon destructans)生长的影响。然后用SA溶液处理二年生人参移栽苗,温室接种人参锈腐病菌,测定了人参根内防御酶系活性（PAL,CAT,PPO,POD）、β-1,3-葡聚糖酶和几丁质酶活性的动态变化。结果表明:浓度为0~200 mg·L^-1 的SA溶液对人参锈腐病菌无直接抑制作用。但SA溶液处理后,人参锈腐病发病率较直接接种处理的下降30%,人参根系PAL、CAT、PPO、POD活性较对照均表现上升趋势,β-1,3-葡聚糖酶和几丁质酶活性也较对照增强,并且经SA诱导后接种锈腐菌的人参体内上述酶活性比只诱导不接种处理上升速度快。这表明SA处理可以改变人参根部相关防御酶的活性,从而提高人参对人参锈腐病的抗性。     

First report of Fusarium proliferatum causing root rot of Gerbera in China

Journal of Plant Diseases and Protection - In January 2018, gerbera plants showed root rot symptoms were found in a greenhouse at Guizhou Horticultural Institute in Guiyang city, Guizhou Province...     

Influence of glyphosate on Rhizoctonia and Fusarium root rot in sugar beet

This study tests the effect of glyphosate application on disease severity in glyphosate-resistant sugar beet, and examines whether the increase in disease is fungal or plant mediated. In greenhouse studies of glyphosate-resistant sugar beet, increased disease severity was observed following glyphosate application and inoculation with certain isolates of Rhizoctonia solani Kuhn and Fusarium oxysporum Schlecht. f. sp. betae Snyd. & Hans. Significant increases in disease severity were noted for R. solani AG-2-2 isolate R-9 and moderately virulent F. oxysporum isolate FOB13 on both cultivars tested, regardless of the duration between glyphosate application and pathogen challenge, but not with highly virulent F. oxysporum isolate F-19 or an isolate of R. solani AG-4. The increase in disease does not appear to be fungal mediated, since in vitro studies showed no positive impact of glyphosate on fungal growth or overwintering structure production or germination for either pathogen. Studies of glyphosate impact on sugar beet physiology showed that shikimic acid accumulation is tissue specific and the rate of accumulation is greatly reduced in resistant cultivars when compared with a susceptible cultivar. The results indicate that precautions need to be taken when certain soil-borne diseases are present if weed management for sugar beet is to include post-emergence glyphosate treatments.     

The occurrence of Fusarium crown and root rot of tomato in Israel

Based upon symptomatology and the results of pathogenicity tests, it has been shown that the Fusarium crown and root rot organism of tomato — previously reported only from North America and Japan — is present in Israel.     

烟草青枯病生防细菌的筛选与生防效果研究

从云南文山烟草种植田烟草植株根围土壤及植株根内生境中分离纯化获得195株细菌,以细菌菌株对青枯雷尔氏菌（Ralstonia solanacearum）YN10的拮抗作用及其产蛋白酶、几丁质酶、纤维素酶和产嗜铁素的活性作为评价指标对其生防潜力进行赋值,对总赋值得分较高的84株菌株做了聚类分析,选择25株拮抗细菌进行了烟草青枯病温室防效试验。结果表明,聚类分析ARDRA图谱中位于不同组的25株拮抗细菌对烟草青枯病都有不同程度的防治效果,菌株K-1-8、R-3-16、R-3-18的温室防效分别为86.66%、84.94%、87.57%;拮抗细菌的生防效果与总赋值存在正相关,相关系数达0.86。     

Large-scale assessment of agricultural practices affecting Fusarium root rot and common bean yield

The relationships between a number of agronomic practices, Fusarium root rot (FRR) measurements and yield variables were characterized at different growth stages in 122 commercial bean fields in Zanjan, Iran. Mean FRR incidence, severity and index differed among growth stages and years. A lower FRR index at growth stage R9 and higher yields were detected in Red beans compared to Pinto and White beans. FRR severity affected the number of pods and seeds per plant. Despite the lack of an impact of initial drought on FRR and yield factors, FRR levels were higher following frequent irrigations at 2–3 days intervals than at longer intervals at R6-7. The highest FRR index at R6-7 (51.9%) and incidence at R9 (69.1%) were associated with the densest category of plant populations. Yield components differed significantly between the levels of plant density at R9. FRR levels at V3 were lower for June plantings than for May-second-week plantings. Lower FRR ratings and higher yields were detected at a seeding depth of 0–5 cm in comparison to 10–20 cm. At R9, FRR levels on beans following maize were lower than those following barley, bean, tomato or wheat. At V3, FRR severity was greater in fields that received 50–500 kg/ha of urea compared to non-fertilized fields. Greater mean FRR index at R6-7 and lower yield levels were associated with the greatest weed density compared to weed-free fields. This new information benefits the systematic understanding of interactions between bean yield, FRR and various agronomic variables at large-scale.     

香蕉枯萎和细菌性软腐病菌的多重PCR检测

香蕉枯萎病菌Fusarium oxysporum f. sp. cubense和细菌性软腐病菌Dickeya zeae的复合侵染为害给香蕉产业发展带来严重挑战, 有必要建立相关病害的多重聚合酶链式反应(multiplex polymerase chain reaction, multiplex PCR)检测技术。本文基于尖孢镰刀菌古巴专化型1号生理小种(F. oxysporum f. sp. cubense race 1, FOC1)基因组contig 438区间(35 631-37 693 bp)(GenBank: AMGP01000438.1)和4号生理小种(F. oxysporum f. sp. cubense race 4, FOC4)基因组contig 195区间(4 028-6 126 bp)(GenBank: AMGQ01000195.1)存在160 bp插入序列差异设计特异扩增引物FOC-F/-R, 同时以香蕉细菌性软腐病菌D. zeae的促旋酶B 亚单位基因(the subunit B of gyrase gene)(GenBank: JQ284039)序列设计特异扩增引物gyrB-F/-R。多重PCR检测结果显示:本技术可在一次PCR扩增反应内同时检测香蕉枯萎病菌1号、4号生理小种和细菌性软腐病菌; 多重PCR的灵敏度结果表明:检测香蕉枯萎病菌的DNA浓度最低限为0.1 ng/μL, 细菌性软腐病菌的灵敏度为10 3cfu/mL;检测结果稳定可靠。因此, 本研究建立的多重PCR检测方法可有效应用于检测香蕉发病组织中的香蕉枯萎病菌和细菌性软腐病菌, 也可用于香蕉种苗和田间土壤带病菌的监测, 为香蕉种植保驾护航。     

马铃薯块茎病原真菌拮抗菌株筛选及优良拮抗菌株鉴定

从马铃薯块茎上分离内生细菌,以块茎病原真菌为指示菌,采用平板对峙法筛选拮抗菌株,并利用形态学特征和16S rDNA基因序列分析对优良拮抗菌株进行鉴定。结果表明,从定西马铃薯块茎中共分离得到72株内生细菌,其中19株对5种块茎病原真菌的抑菌率均高于51.87%,特别是内生细菌6-5和5-6分别对马铃薯炭疽病菌Colletotrichum coccodes和马铃薯黑痣病菌Rhizoctonia solani的抑菌率达85.82%和72.18%,且具有固氮和产吲哚乙酸(IAA)功能,其产IAA量分别为3.37 mg/L和19.25 mg/L;根据形态特征及16S rDNA基因序列将菌株5-6鉴定为萎缩芽胞杆菌Bacillus atrophaeus,菌株6-5鉴定为贝莱斯芽胞杆菌Bacillus velezensis。     

南方红豆杉根腐病病原及其拮抗芽胞杆菌的鉴定

经形态学特征观察、致病性测定及rDNA-ITS序列分析,首次确定红豆杉根腐病病原为尖孢镰刀菌(Fusarium oxysporum)。采用平板对峙培养法从健康植株根际土壤中筛选得到3株对尖孢镰刀菌具有明显拮抗作用的芽胞杆菌YB6、YB15、YB37。经形态学、生理生化及16SrDNA同源性分析,并通过构建16SrDNA系统发育树,将YB6、YB15和YB37分别鉴定为蜡样芽胞杆菌(Bacillus cereus)、解淀粉芽胞杆菌(B.amyloliquefaciens)和多黏类芽胞杆菌(Paenibacillu polymyxa),其中多黏类芽胞杆菌拮抗效果最好,具有进一步研究开发的潜力。本研究通过对南方红豆杉根腐病病原鉴定及其拮抗芽胞杆菌的筛选,对该病的防治提供了理论依据。