黄瓜枯萎病拮抗菌的拮抗促生因子检测及生物效应研究

以黄瓜枯萎病病原菌,尖孢镰刀菌黄瓜专化型(FOC,Fusarium oxysporum f.sp.cucumerinum)为靶标筛选拮抗菌。通过初筛和复筛,获得2株对尖孢镰刀菌黄瓜专化型拮抗效果稳定、拮抗能力较强的细菌QHZ-Yb1和QHZ-Yb2(以下简称,Yb1和Yb2),采用平板对峙法测定其拮抗作用,抑菌带宽度达3.37 mm和3.42 mm,抑菌圈直径2.7 cm,抑菌率分别达到61.9%和62.3%;通过形态学结合生理生化及菌株的16S rDNA序列分析,初步确定这两株菌均为萎缩芽孢杆菌(Bacillus atrophaeus);潜在拮抗促生因子的测定结果表明:菌株Yb1和Yb2具有多种拮抗促生因子,其脂肽类粗提取物的抑菌率分别达到57.4%和58.0%,生长素IAA的分泌量可达1.56 mg·L~(-1)和3.69 mg·L~(-1),溶P量为0.77 mg·L~(-1)和1.19 mg·L~(-1),两个菌株均可产嗜铁素、分泌酪蛋白酶;种子萌发试验结果表明:Yb1和Yb2菌液均可促进黄瓜种子的萌发;菌株生物效应的盆栽试验结果表明:Yb1、Yb2以及Yb1+Yb2菌悬液的处理不仅对黄瓜枯萎病有明显的生防效果,而且可显著增加黄瓜植株的生物量,增加黄瓜植株根际土中细菌和放线菌的数量,减少真菌和尖孢镰刀菌的数量,尤其以Yb1+Yb2菌悬液的处理效果最显著,对黄瓜枯萎病的发病率降低11.11个百分点,植株生物量增加56.7%。结论:菌株Yb1和Yb2具有生防潜力,两菌株配合运用效果更好。     

Rootstock resistance to Fusarium wilt and effect on watermelon fruit yield and quality

The potential of grafted watermelon for resistance toFusarium oxysporum f.sp.niveum on some Curcurbitaceae,Lagenaria, Luffa, Benincasa and commercial rootstocks was evaluated. Effects of grafting on yield and quality of diseased plants were evaluated. All grafted plants and rootstocks were resistant to the three known races (0, 1, and 2) ofF. oxysporum f.sp.niveum except watermelon cv. ‘Crimson Tide’, which was susceptible to race 2. Fruit yield was positively (21–112%) affected byLagenaria rootstocks but negatively affected (200–267%) byCucurbita rootstocks when compared with the control. While only minor differences in fruit quality were determined in control and grafted plants onLagenaria rootstocks, the quality parameters for watermelon grafted ontoCucurbita rootstocks were lower than in the control. The reasons for low yield and quality might be due to an incompatibility betweenCucurbita rootstocks and watermelon. These results showed that rootstock influence on disease resistance as well as yield and quality of scion fruit is important in determining the potential use of grafting applications in watermelon. http://www.phytoparasitica.org posting Feb. 2, 2003.     

四季豆枯萎病病原鉴定及防治

从南宁市郊11个病区采集的四季豆枯萎病株标样,经分离培养鉴定和致病性测定,证明其病原菌为尖孢镰刀菌菜豆专化型(Fusarium oxysporum f. sp. phaseoli Kend & Syd)。此病在南宁于4月上中旬四季豆初花期开始发生,5月中下旬盛花至结荚期为发病高峰期。用滤纸碟法进行药效试验的结果,40%灭病威300-500倍液的抑菌圈最大,田间灌根防治也有一定效果。可用种子重量的0.5%多菌灵可湿性粉拌种。品种间抗病性有显著差异,秋抗19号和秋抗6号较抗病。     

Fusarium wilt on sweet basil: Cause and sources in southeastern Spain

This study concerned a new disease detected in 1997 in southeastern Spain — Fusarium wilt in basil (Ocimum basilicum L.), caused byFusarium oxysporum f.sp.basilici. Its importance was evaluated at two locations in the Almería area, where 14% of the plants presented symptoms of the disease after 4 months of cropping. The search for sources of the disease inoculum was centered on the health of the seeds and the polypropylene trays that were reused for plant production. Analysis of four lots of seeds from Germany and Italy showed that two of them harboredF. oxysporum f.sp.basilici. This finding was confirmed by the analysis of seeds collected from diseased plants. Furthermore, analysis of three reused trays revealed the presence of the pathogen on them and it was concluded that the trays acted as the source of dispersion of the mycosis. http://www.phytoparasitica.org posting July 14, 2004.     

AM真菌与西瓜枯萎病关系初探

 在温室盆栽条件下研究了丛枝菌根(Arbuscular Mycorrhiza,AM)真菌Gigaspora rosea Nicol.& Schenck、Glomusmosseae(Nicol.& Gerd.) Gerdemann & Trappe和Glomus versiforme(Karsten) Berch与西瓜枯萎病菌(Fusariumoxysporum f. sp. niveum)的关系。结果表明,接种AM真菌能促进西瓜植株的生长发育,增加植株干重;显著减少根内和根围土壤中镰刀菌群体数量及其对根系的侵染率;降低枯萎病发病率和病情指数,从而减轻西瓜枯萎病的危害。接种F.oxysporum f. sp. niveum能降低AM真菌对西瓜的侵染率,并且AM真菌与镰刀菌的不同接种时间和顺序影响西瓜枯萎病的发生发展,证实AM真菌与镰刀菌存在竞争关系。另外,AM真菌对西瓜高感枯萎病品种的防治效果优于抗病品种,说明高感品种对菌根的依赖性较大。     

Latent infection in tulip bulbs by Fusarium oxysporum

Latent infections byFusarium oxysporum Schlecht. f. sp.tulipae can easily be induced in tulip bulbs in the laboratory. They may also occur in commercial stocks and their presence in planting stocks of susceptible cultivars may affect the health of the daughter bulbs harvested in the following year, even when the planted bulbs have been disinfected. Latent infections do probably not reduce the flowering ability of bulbs during forcing in winter. By histopathological techniques the infective hyphae were shown to penetrate the host tissue superficially in latent infections. The pathogen remains viable during dry storage of the bulbs for several months and can become reactivated after planting.Samenvatting Het is mogelijk latent blijvende infecties veroorzaakt doorFusarium oxysporum Schlecht. f. sp.tulipae kunstmatig op te wekken (Fig. 2), waarbij geen of voor de ziekte aspecifieke, onopvallende symptomen ontstaan (Fig. 1). Ook in partijen, waarin de ziekte uitval heeft veroorzaakt, kunnen in bollen die op het oog gezond lijken, latente infecties voorkomen. Indien dergelijke bollen worden geplant, is de kans aanwezig dat de ziekte in een onverwacht grote mate voorkomt in de oogst van het volgende jaar (Tabel 2). Dit geldt eveneens indien het plantgoed is ontsmet en geplant in onbesmette grond. Waarschijnlijk heeft de aanwezigheid van latente infecties in bollen bestemd voor de bloemproduktie in de winter geen invloed op de slaging van de bloei, omdat de periode waarin de temperatuur een voor de parasiet gunstige waarde heeft, te kort is. De schimmel blijft inactief tijdens de droge bewaring van de bollen en wordt weinig beïnvloed door de bewaar-omstandigheden. In een aantal gevallen groeit hij na het planten uit in de rokken van de moederbol (Tabel 3), van waaruit hij in het late voorjaar de jonge bollen kan infecteren. Uit histologisch onderzoek bleek, dat het pathogeen meestal of uitsluitend via de huidmondjes in de onbeschadigde bolrok binnendringt, van waaruit hij inter- en later intracellulair groeiend in korte tijd het omringende weefsel vernietigt. Indien de infectie door nog onbekende oorzaak in de latente fase overgaat, kan het mycelium slechts spaarzaam in de ademholte of intercellulair tussen de deze omringende cellen worden gevonden.     

Extracts of killedPenicillium chrysogenum Induce resistance against Fusarium wilt of melon

Dry fungal biomass ofPenicillium chrysogenum (dry mycelium), a waste product of the pharmaceutical industry, was extracted with water and applied to the roots of melon plants before or after inoculation withFusarium oxysporum f.sp.melonis (Font). Seedlings (4–6 days after emergence) treated with either acidic dry mycelium extract (DME) or neutralized dry mycelium extract (NDME) were protected against challenge infection withFom. A single drench with 2–5% DME applied 12–72 h before inoculation provided significant control of the disease compared with water-drenched, challenged seedlings. No protection was seen in plants treated 0–6 h before inoculation or 0–48 h after inoculation. Neither DME nor NDME (0.5–5%) had any effect on fungal growthin vitro, which implied that disease controlin vivo was mediated by induced resistance. The resistance induced by DME protected melon plants not only against race 1,2, but also against the three other races of the pathogen, indicating a race-non-specific resistance againstFom. Both DME and NDME significantly increased peroxidase activity and free L-proline content in seedlings 12 h and 48 h after soil drench, respectively. Resistance to Fusarium wilt was significantly associated with elevated levels of peroxidase activity but not with free L-proline content. Thus, peroxidase might be involved in the defense mechanisms activated by DME or NDME. http://www.phytoparasitica.org posting Aug. 31, 2001.     

Bacillus subtilis as an alternative biologically based strategy for controlling Fusarium wilt disease in tomato: A histological study

The employment of formulateBacillus subtilis as a biocontrol agent successfully controlledFusarium oxysporum f.sp.lycopersici within tomato seedlings (in vivo). B. subtilis was able to proted cortex and vascular tissues of tomato against progression of the wilt pathogen. No changes were observed in tomato tissues due to application ofB. subtilis except for hypertrophy and elongation of cortex tissues, which indicates the production of plant growth hormones byB. subtilis.     

Efficacy of bacterial antagonists and different commercial products against Fusarium wilt on rocket

Seven experimental trials were carried out to evaluate the efficacy of the bacterial strains Achromobacter xylosoxydans AM1 and Serratia sp. DM1 obtained from suppressive soils and from soilless used rockwool substrates (Pseudomonas putida FC6B, Pseudomonas sp. FC7B, Pseudomonas putida FC8B, Pseudomonas sp. FC9B and Pseudomonas sp. FC24B) against Fusarium wilt on rocket caused by Fusarium oxysporum ff. spp. raphani and conglutinans. Along with these strains, two commercial bioproducts (RootShield—Trichoderma harzianum T22; Cedomon—Pseudomonas chlororaphis MA342) were also tested. Different application strategies such as soil treatment (trials I to VI; 10⁷ and 10⁸ CFU ml⁻¹) and root dipping (trial VII; 10⁸ and 10⁹ CFU ml⁻¹) were performed in a glasshouse in order to test the efficacy of the bacterial strains against Fusarium oxysporum ff. spp. raphani and conglutinans. The lowest disease incidence (16.7%) was observed with the application of Achromobacter sp. AM1, Serratia sp. DM1 at 10⁸ CFU ml⁻¹ and Pseudomonas sp. FC9B at 10⁷ CFU ml⁻¹ against F. oxysporum f. sp. conglutinans (experiment I). Maximum plant biomass (5.0 g/plant) was registered in Serratia sp. DM1 at 10⁸ CFU ml⁻¹ treated plants in trial IV. The trials against F. oxysporum f. sp. raphani (experiment II) showed that the application of Pseudomonas sp. FC7B, P. putida FC8B at 10⁸ CFU ml⁻¹ and P. chlororaphis MA342 at 7.5 × 10⁶ CFU ml⁻¹ significantly reduced disease incidence to values ranging between 87% and 92%. The highest plant biomass was recorded with the application of Achromobacter sp. AM1 and P. putida FC6B at 10⁷ CFU ml⁻¹ (3.9 to 4.2 g) carried out 7 days before the artificial inoculation of the pathogens (trial IV). The present study showed the potential biocontrol activity of the bacterial strains Achromobacter sp. AM1, Serratia sp. DM1 and Pseudomonas sp. FC9B against F. oxysporum f. sp. conglutinans and of Pseudomonas sp. FC7B, P. putida FC8B, P. chlororaphis MA342, Achromobacter sp. AM1 and P. putida FC6B against F. oxysporum f. sp. raphani. Growth-promoting activity of biocontrol bacteria used during the trials was observed.     

番茄枯萎病菌转录因子FolMsn2的生物学功能

为探究转录因子FolMsn2在番茄枯萎病菌Fusarium oxysporum f. sp. lycopersici生长发育及致病过程中的作用,以番茄枯萎病菌野生型菌株4287为材料,利用基因敲除方法获得FolMSN2基因缺失突变体△Folmsn2及回补体菌株△Folmsn2-C,通过测定菌株的生长速率、孢子产量及致病力等表型初步分析番茄枯萎病菌中FolMSN2的生物学功能。结果显示,与野生型菌株4287相比,FolMSN2基因敲除突变体△Folmsn2生长速率显著减慢,菌株产孢量显著下降,仅为野生型菌株4287产孢量的6.7%;外界环境压力胁迫试验结果显示,FolMSN2基因缺失突变体△Folmsn2对渗透压、盐胁迫的敏感性显著提高,而对细胞壁、氧化压力胁迫变得更加耐受。此外,FolMSN2基因缺失突变体△Folmsn2对番茄苗及果实的致病力显著下降,进一步分析发现FolMSN2基因缺失影响其对玻璃纸的穿透能力;亚细胞定位结果表明,FolMsn2蛋白定位于细胞核内。表明FolMsn2参与调控番茄枯萎病菌的营养生长、无性繁殖以及对不同环境胁迫的应答过程,其可能通过影响菌丝对寄主的穿透能...     

Allelism of theFcu-1 andFoc genes conferring resistance to fusarium wilt in cucumber

The inheritance of resistance toFusarium oxysporum f.sp.cucumerinum race 1 was determined in the cucumber cv. WIS-248 by analyzing segregation of F₁, F₂, and BC populations of crosses with the susceptible cv. Straight-8. Resistance was conferred by a single dominant gene. In an allelism test, it was proven that theFcu-1 gene, which confers resistance toF. oxysporum f.sp.cucumerinum races 1 and 2 in cucumber cv. SMR-18 and theFoc gene, which confers resistance toF. oxysporum f.sp.cucumerinum race 2 in cucumber cv. WIS-248, are indistinguishable.     

Host genotype- and temperature-dependent colonizationof In vitro carnation callus cultures byFusarium oxysporum f.sp.dianthi race 2

Differentin vivo resistance/susceptibility levels of 14 carnation cultivars toFusarium oxysporum f.sp.dianthi race 2, the causal agent of Fusarium wilt disease of carnation, were also expressed in anin vitro system and assayed as the degree of fungal colonization of callus cultures at 20° C. Temperature influenced thein vitro expression of carnation resistance. An incubation temperature of 27° C increased the colonization of calli derived from both the susceptible (‘Corrida’ and ‘Ambra’) and the resistant (‘Pulcino’ and ‘Pallas’) cultivars. At 15°C, the colonization of calli derived from Pulcino and Pallas diminished significantly more than for Ambra and Corrida. Inhibition of fungal growth on resistant calli was correlated to retardation in hyphal development. Both scanning electron microscopy and light microscopy observations showed that hyphae did not penetrate into carnation cells.     

Development of Fusarium Wilt-resistant Genotypes in Safflower (Carthamus tinctorius)

Screening of 51 promising safflower germplasm lines in Fusarium wilt-infested plots resulted in identification of highly wilt-resistant selections viz., 86-93-36A, 237550, VI-92-4-2 and II-13-2A, with some moderate resistance in HUS-305. Progenies from crosses made using these resistant lines were tested for their reaction to wilt. F₁ progenies from 86-93-36A × 237550 and 86-93-36A × II-13-2A recorded zero wilt incidence, while 237550 × 86-93-36A was highly resistant to the Rajendranagar geographical isolate. The reaction for the three progenies showed stability for wilt resistance with no segregation until the F₇ generation. Geographical isolates of Fusarium oxysporum f. sp. carthami (Foc) were collected from different safflower growing regions and tested for their pathogenic variability on six host differentials under glasshouse conditions. Based on the reaction of the differentials, the Foc isolates were grouped into four biotypes. The three resistant progenies were tested for their reaction to the four biotypes. The progeny of cross 86-93-36A × 237550 showed an immune reaction to all the biotypes, except for a highly resistant reaction to biotype 3. The progenies of the two other crosses (86-93-36A × II-13-2A and 237550 × 86-93-36A) exhibited immune reactions to biotypes 2,3 and 1,3, respectively, and were highly to moderately resistant to biotypes 1,4 and 2,4, respectively.     

Physiologic races ofFusarium oxysporum f.sp.melonis in the southeastern anatolia region of turkey and varietal reactions to races of the pathogen

Thirty-four isolates ofFusarium oxysporum f.sp.melonis (F.o.m.) obtained from 205 fields in melon-producing areas in the southeastern Anatolia Region of Turkey were identified on the basis of colony morphology and pathogenicity by the root dip method. In this region the mean prevalence of wilt disease was 88.1% and the mean incidence of disease was 47.5%. Physiologic races 0, 1, 2, and 1,2 of the pathogen were determined by their reactions on differential melon cultivars ‘Charentais T,’ ‘Isoblon’, ‘Isovac’ and ‘Margot’ in the greenhouse. Race 1,2, representating 58.8% (20/34) of all isolates, was widely distributed. Of the other pathogenic isolates, eight were identified as race 0, five as race 1, and one as race 2. This is the first report of physiologic races ofF.o.m. in Turkey. Of 44 melon cultivars tested in the greenhouse for resistance toF.o.m. races, 36 were found to be moderately resistant to race 0, 17 were susceptible to race 1,2, 34.1% were highly resistant to race 1, and 52.2% had moderate resistance to race 2. http://www.phytoparasitica.org posting July 16, 2002.     

苦瓜枯萎病菌的鉴定及其遗传多样性分析

 对分离获得的32株苦瓜枯萎病菌菌株进行形态学特征和寄主专化型测定, 结果表明, 测试的苦瓜枯萎病菌株均为尖孢镰刀菌苦瓜专化型 (Fusarium oxysporum f. sp. momordicae), 这些菌株可以侵染苦瓜和瓠瓜幼苗, 但不侵染其他葫芦科瓜类作物。对苦瓜枯萎病菌菌株的rDNA-ITS区 (ITS1、5.8S和ITS2)序列进行扩增测序, 结果显示其序列长度均为456 bp;聚类分析表明测序菌株与镰刀菌属中尖孢镰刀菌不同专化型的菌株聚为一群。利用RAPD标记技术分析苦瓜枯萎病菌的遗传多样性, 结果显示苦瓜枯萎病菌株与其他葫芦科瓜类作物枯萎病菌株间的遗传相似系数范围为0.59~0.99, 当遗传相似系数为0.85时, 供试的48个菌株分成10个类群 (G_1~10)。在RAPD聚类树中所有苦瓜枯萎病菌株聚在一个分支上 (G₁群), 菌株间的遗传相似系数范围为0.92~1.00, 具有较高的遗传相似性, 且菌株的聚群与地理来源存在一定的相关性。     

草莓枯萎病菌抗戊唑醇突变体ZY-W的生理生化特性

为明确抗戊唑醇草莓枯萎病菌 Fusarium oxysporum f.sp. fragariae 突变体ZY-W的生理生化特性,分析其抗性风险及可能的抗性机制,比较了对戊唑醇抗性达34.2倍的ZY-W和敏感菌株ZY在苯丙氨酸解氨酶(PAL)及过氧化物酶(POD)活力、对渗透压的敏感性、相对渗率、可溶性蛋白含量及酯酶同工酶图谱等方面的差异。结果表明:ZY-W突变菌株体内的POD和PAL活力均高于ZY;经不同浓度药剂处理0～24 h,2菌株PAL活力均呈先上升后下降的趋势,并在处理后1.5 h达到最高值;2菌株的POD活力则一直处于上升状态,24 h时达到最高值,且此时2菌株间POD活力差异最大;仅用清水处理0～24 h,2菌株的PAL和POD活力均一直处于上升状态。在不同处理时间及药剂浓度下,ZY的相对渗率为ZY-W的1.0～2.4倍,表明ZY-W菌株的细胞膜透性低于ZY;ZY-W对渗透压的敏感性及体内可溶性蛋白含量均显著高于ZY,其中ZY-W的可溶性蛋白含量是ZY的1.3倍;在突变菌株ZY-W的酯酶同工酶图谱中发现了 Rf值为0.24的特征性谱带。表明草莓枯萎病菌对戊唑醇产生抗性的同时,伴随着其生理生化特性的改变。     

Induction of heat resistance in Fusarium oxysporum and Verticillium dahliae caused by exposure to sublethal heat treatments

The effects of sublethal heat treatments on heat resistance were studied forFusarium oxysporum f.sp.dianthi (Fod) andVerticillium dahliae (Vd), one isolate of each pathogen. Treatments of propagule suspensions of Fod at 55°C and of Vd at 45°C for 30 min were survived by less than 0.001% and 0.01% of the propagules, respectively. Pretreatment of suspensions of Fod at 45°C increased survival of the 55°C treatment up to 0.73% of the propagules and pretreatment of suspensions of Vd at 40°C increased survival of the 45°C treatment up to 0.40%. Induction of heat resistance was dependent on duration of the exposure to the sublethal temperature. With Fod, this duration was shorter for propagules from old cultures than for those from young cultures. Pretreatment at 45°C of a suspension of an 1-week-old culture of Fod induced resistance when lasting 30 min or longer, but not when 20 min or shorter. With Vd, the duration of the pretreatment inducing heat resistance depended on type of culture — white or black — due to differences in microsclerotia formation. Implications of induced heat resistance for control of plant diseases by thermotherapy are discussed.     

Suppression of Fusarium wilt of spinach with compost amendments

The effect of different organic composts on the suppression of wilt disease of spinach caused by Fusarium oxysporum f. sp. spinaciae was evaluated in a continuous cropping system in both containers and in microplot field trials. Test soils infested with the pathogen were amended with wheatbran, wheatbran and sawdust, coffee grounds, chicken manure, or mixture of different composts with and without 5% (w/w) crab shell powder either once (5%, w/w) or continuously (2.5%) into the test soils infested with the pathogen. In the container trials, the soil amended with composts became suppressive to disease development on the second and third cropping. The suppressive effect was notable in the soil amended with the mixture of compost with and without crab shell powder. The coffee compost lowered soil pH but became suppressive to the disease after modifying the soil pH. In the field trial using the mixture of the different composts containing 5% crab shell powder, a combination of 5% before the first cropping and 2.5% every second cropping gave stable disease control and promoted plant growth. After compost amendment, populations of fungi, bacteria and actinomycetes as measured by dilution plate counting and the total microbial activity as evaluated by fluorescein diacetate hydrolysis increased and population of the pathogen gradually decreased. These phenomena were especially notable in soils amended with the mixture of different composts. These results indicate that diversity in the organic materials promotes higher microbial activity and population in the soil thereby enhancing disease suppressiveness.