Evaluation of plant-growth-promoting rhizobacteria, acibenzolar-S-methyl and hymexazol for integrated control of Fusarium crown and root rot on tomato

BACKGROUND: Plant growth‐promoting rhizobacteria (PGPR) can be potential agents for biological control of plant pathogens, while their combined use with conventional pesticides may increase their efficacy and broaden the disease control spectrum. The effect of four different Bacillus sp. PGPR strains (B. subtilis GB03 and FZB24, B. amyloliquefaciens IN937a and B. pumilus SE34) applied individually and in mixtures, as well as in combined use with acibezolar‐S‐methyl (ASM) and hymexazol, on plant growth promotion and on the control of Fusarium crown and root rot (FCRR) of tomato was evaluated. RESULTS: All PGPR strains promoted the tested plant growth characteristics significantly. A higher promoting effect was provided by SE34. Experiments on population dynamics of PGPR strains revealed that, after 28 days of incubation, populations of strain SE34 remained stable, while the remaining bacterial strains showed a slight decline in their population densities. The GB03 and FZB24 strains provided a higher disease suppression when applied individually. However, application of IN937a in a mixture with GB03 provided a higher control efficacy of Fusarium oxysporum f. sp. radicis‐lycopersici (Forl). Treatment of tomato plants with ASM resulted in a small reduction in disease index, while application of hymexazol provided significantly higher control efficacy. Combined applications of the four PGPR strains with either ASM or hymexazol were significantly more effective. CONCLUSION: The results of the study indicate that, when bacilli PGPR strains were combined with pesticides, there was an increased suppression of Forl on tomato plants, and thus they may prove to be important components in FCRR integrated management. Copyright © 2011 Society of Chemical Industry     

Combining nonpathogenic strains of Fusarium oxysporum with sodium chloride to suppress fusarium crown rot of asparagus in replanted fields

Nonpathogenic strains of Fusarium oxysporum (NPFO) were tested alone, and in combination with rock salt (NaCl), for their ability to suppress fusarium crown and root rot of asparagus in replanted fields. Five NPFO strains were first screened with and without NaCl in the glasshouse using autoclaved asparagus soil mixed with potting mix. Asparagus roots were treated with NPFO suspensions or water, then inoculated 1 week later with pathogenic F. oxysporum ; then after 1 week pots received 100 mL 1% NaCl or water. After 12 weeks the NPFO strain CS-20 increased root weight when compared with controls. Rock salt did not affect root growth. Root lesions were reduced relative to the control by all NPFO strains and by NaCl applications, but there were no interactions between NPFO and NaCl. The NPFO strains CS-20, CWB 314 and CWB 318 were compared with no treatment in two 4-year replanted field studies in Hamden, and Windsor, CT, USA. Crowns were treated with NPFO at planting, and NaCl was broadcast at 280 kg ha⁻¹, and at 560 kg ha⁻¹ in later years. CWB 318 reduced disease at both sites and increased marketable yield in Hamden. Treatment with NaCl increased yield by 29% over controls in Windsor, but did not increase yield in Hamden. Recovered root isolates of F. oxysporum categorized by heterokaryon tests revealed that, in the glasshouse, CS-20 colonized roots better than other strains, while CWB 318 was the only strain found on roots from field plots after 4 years. Applications of NaCl did not hinder the suppressive ability of the nonpathogenic strains. The perennial nature of asparagus may require that nonpathogenic strains possess superior survival traits along with biocontrol traits.     

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。     

番茄疫霉根腐病生防菌的分离鉴定及其防治效果

 利用平板对峙法从山东寿光采集的土样中筛选出1株对番茄疫霉根腐病菌Phytophthora capsici Leonian具有较好拮抗作用的生防菌株ZF50,抑菌率为76.26%。经形态学、生理生化特性以及系统发育树分析,确定菌株ZF50为贝莱斯芽胞杆菌Bacillus velezensis。该菌株具有较广谱的抑菌能力,且在活体盆栽和田间小区条件下,将浓度为1×10⁸ cfu·mL^-1 ZF50菌悬液10 mL灌根后,对番茄疫霉根腐病的防治效果最好,盆栽防效为55.55%,田间小区防效为43.52%;且该菌株还具有明显的促生效果和产吲哚乙酸的能力。     

番茄疫霉根腐病生防菌的分离鉴定及其防治效果

 利用平板对峙法从山东寿光采集的土样中筛选出1株对番茄疫霉根腐病菌Phytophthora capsici Leonian具有较好拮抗作用的生防菌株ZF50,抑菌率为76.26%。经形态学、生理生化特性以及系统发育树分析,确定菌株ZF50为贝莱斯芽胞杆菌Bacillus velezensis。该菌株具有较广谱的抑菌能力,且在活体盆栽和田间小区条件下,将浓度为1×10⁸ cfu·mL^-1 ZF50菌悬液10 mL灌根后,对番茄疫霉根腐病的防治效果最好,盆栽防效为55.55%,田间小区防效为43.52%;且该菌株还具有明显的促生效果和产吲哚乙酸的能力。     

Granular formulation of Fusarium oxysporum for biological control of faba bean and tomato Orobanche

BACKGROUND: Orobanche spp. represent a serious threat to a wide range of crops. They are difficult targets for herbicides, and biological control could provide a possible solution. This work therefore aimed to formulate mycoherbicides of Fusarium with adequate shelf life and virulence against Orobanche but safe to faba bean and tomato. RESULTS: Only two isolates of Fusarium oxysporum Schlecht. (Foxy I and Foxy II) obtained from diseased Orobanche shoots were found to be pathogenic to Orobanche crenata Forsk. and Orobanche ramosa L. Conidial suspension of both isolates significantly decreased germination, attachments and tubercles of Orobanche. Microconidia and chlamydospores of both isolates were formulated as mycoherbicides encapsulated in a wheat flour–kaolin matrix (four different formulations). All formulations greatly diminished Orobanche emerged shoots, total shoot number, shoot height, attachment of emerged shoots, the germinated seeds that succeeded in emerging above the soil surface and dry weight. Meanwhile, disease incidence and disease severity of emerged shoots were enhanced. The shelf life was adequate, particularly for coarse, freshly prepared, low‐temperature‐stored, microconidia‐rich formulations. The induced growth reduction of Orobanche‐infected host plants seemed to be nullified by formulations, particularly at the highest dose. CONCLUSION: These formulations seemed to destroy Orobanche but appeared harmless to host plants. Hence, they could be efficiently used as mycoherbicides for biological control of Orobanche in faba bean and tomato. Copyright © 2008 Society of Chemical Industry     

小麦茎基腐病生防菌株YB-161的分离鉴定及防效测定

为筛选防治小麦茎基腐病的高效生防菌株,采用稀释涂布法从小麦茎基腐病病土中分离细菌,以假禾谷镰孢Fusarium pseudograminearum为靶标菌,通过平板对峙培养法和室内盆栽试验筛选优良菌株并测定其田间防治效果,分析优良菌株发酵滤液对假禾谷镰孢的抑菌能力,并结合形态特征、Biolog微生物自动鉴定系统和gyrA序列分析对其进行种类鉴定,以及测定该菌株的抑菌谱。结果表明,10份供试土样中共分离到98株细菌,对假禾谷镰孢的菌丝生长抑制率超过40.00%的菌株有14株,其中菌株YB-161对假禾谷镰孢的菌丝生长抑制率最高,达63.50%。室内盆栽试验结果显示,菌株YB-161处理小麦的病情指数最低,为31.40,对小麦茎基腐病的防治效果最好,为68.15%,其对小麦也表现出较好的促生作用。田间调查结果显示,菌株YB-161菌液拌种处理对小麦茎基腐病的田间防治效果高于52.35%,并对小麦具有一定的增产作用。菌株YB-161的发酵滤液5倍稀释液和10倍稀释液对假禾谷镰孢的菌落抑制率分别达66.67%和44.33%,该菌株被鉴定为解淀粉芽胞杆菌Bacillus amyloliquefaciens。此外,菌株YB-161对辣椒炭疽病菌Colletotrichum capisci、烟草疫霉病菌Phytophthora parasitica等5种植物病原真菌均有较好的拮抗作用。表明生防菌株YB-161对绿色防控小麦茎基腐病具有良好的开发利用潜能。     

Identification,pathogenicity and community dynamics of fungi and oomycetes associated with pea root rot in northern France

The pea root rot complex is a major concern for green pea production worldwide. This study aimed at characterizing its composition and dynamics throughout a cropping season in northern France. To this end, fungi and oomycetes were isolated from green pea plant roots with symptoms sampled at the flowering stage in 22 fields in 2017, and at the pea emergence, elongation and flowering stages in two fields in 2018. Out of 646 isolates collected, 317 were identified using molecular markers. Fusarium oxysporum, F. solani and F. redolens were highly predominant. Pathogenicity tests separated the isolates into four aggressiveness groups. F. solani isolates were the most aggressive. Phylogenetic analysis of their TEF1 sequences showed that they mainly belonged to the F. pisi lineage, and that F. oxysporum isolates were genetically close to isolates from the UK that did not belong to the forma specialis pisi. In addition, several Clonostachys rhizophaga isolates are reported for the first time to cause pea root rot. The oomycetes were rarely found and were represented by a few Pythium spp. isolates. Lastly, this study shows that the fungal and oomycete communities associated with pea root rot change during the cropping season. The level of dissimilarity of the root-rot-associated communities decreased throughout the cropping season towards a more similar composition at the flowering stage, dominated by F. solani, F. oxysporum and F. redolens. The proportion of nonpathogenic to weakly pathogenic isolates decreased progressively during the growing season in favour of moderately to highly pathogenic isolates.     

芽胞杆菌组合BCL-8对番茄的促生防病效果及其促生机制初探

对芽胞杆菌组合BCL 8及其单一菌株对番茄的促生和抗病效果进行了比较研究。组合BCL 8可明显提高种子活力和发芽率,使发芽率提高10%;与单一菌株相比,组合BCL 8对番茄苗期的促生抗病作用更为显著,株高、鲜重和干重分别增加了117.08%、125.74%和140.51%,对番茄立枯病的防治效果达58.62%。采用福林 酚试剂法、3,5 二硝基水杨酸比色法和电导法分别测定组合BCL 8和单一菌株处理后种子的蛋白酶、α 淀粉酶和β 淀粉酶活性及发芽种子电导率的变化,结果表明,经组合BCL 8浸种处理后,种子的蛋白酶、α 淀粉酶和β 淀粉酶活性分别提高了299.91%、96.74%和99.98%,种子的电导率比对照降低了10.02%,初步揭示了BCL 8促进种子发芽的机制。     

太子参根腐病病原菌的鉴定及防治药剂筛选

为有效防控太子参根腐病,本研究于2017年3月-2019年6月自福建省宁德市柘荣县太子参主产区采集具有典型根腐病症状的植株和块根病样,分离纯化获得病原菌,利用形态学特征、分子生物学特性及致病性测定对其进行鉴定;同时通过测定平板抑制率和扫描电镜观察分析6种杀菌剂对太子参根腐病病原菌菌丝生长的抑制效果。结果表明：太子参根腐病典型症状为苗期和生长期植株萎蔫、根部和茎基部褐变;块根表皮呈现开裂、组织褐变和干腐状。分离纯化后获得22株培养性状一致的菌株,结合菌株的形态学特征、EF-1α基因序列和特异性引物FOF1/FOR1检测,将该病原菌鉴定为尖孢镰刀菌Fusarium oxysporum。致病性测定结果表明其发病症状与田间表现一致,且符合科赫氏法则。经筛选6.6%嘧菌酯·1.1%咯菌腈·3.3%精甲霜灵悬浮种衣剂和25%吡唑醚菌酯乳油对该病原菌有良好的抑制效果,稀释至2 000倍液的抑制率分别为78.52%和75.36%;扫描电镜观察显示这2种杀菌剂处理组的菌丝体发育畸形、断裂、表面皱缩或消解,未见产孢细胞;而无菌水对照处理组的菌丝体生长正常,可见产孢细胞。表明筛选到的2种杀菌剂可用于防治由尖孢镰刀菌引起的太子参根腐病。     

棉花黄萎病、枯萎病拮抗细菌的筛选及其生长特性的研究

从广西大学、中国农业科学院植物保护研究所黄萎病、枯萎病发病较轻的试验棉田根围土中筛选出5株拮抗性能较高的细菌,其中一株S6经过16s rDNA鉴定为枯草芽孢杆菌。经过测定,S6的最适生长温度为28℃,最适pH为7,对NaCl的耐受达到10%。     

Biological control of avocado white root rot with combined applications of Trichoderma spp. and rhizobacteria

This study tested the effectiveness of single and combined applications of Trichoderma and rhizobacterial strains to control white root rot (WRR) caused by Rosellinia necatrix in avocado plants. Three Trichoderma, two T. atroviride and one T. virens monoconidal strains and four bacterial strains (Bacillus subtilis, Pseudomonas pseudoalcaligenes and two P. chlororaphis) were assayed to determine their compatibilities in vitro. In addition, the effects of the bacterial filtrates were evaluated against the Trichoderma strains and reciprocally; these filtrates were applied alone or in combination to determine their effectiveness against R. necatrix. Individual control agents or combinations of them were applied to avocado plants that were artificially inoculated with a virulent R. necatrix strain. Compatibility between the combined Trichoderma applications and the bacterial strains was observed and these combinations significantly improved the control of R. necatrix during the in vitro experiments. A relative protective effect of some Trichoderma and bacteria was observed on the control of avocado WRR when they were applied singly. The combinations of T. atroviride strains with bacterial strains P. chlororaphis and P. pseudoalcaligenes showed a better control of avocado WRR, whereas the rest of Trichoderma and bacteria combinations also reduced significantly the level of disease and induced a delay at the onset of disease with respect to avocado plants inoculated either with Trichoderma or bacteria.     

拮抗放线菌B1菌株鉴定及其防治番茄灰霉病的初步研究

为明确放线菌B1菌株在植物病害生物防治中的应用潜力,采用平板对峙培养法、离体叶片和果实及温室盆栽苗测定其抑菌作用,通过多相分类法研究其分类地位,并且采用单因子试验与正交试验相结合的方法,筛选出该菌株的液体发酵培养基配方.结果表明:菌株B1对10种植物病原真菌和3种植物病原细菌有抑制作用,其中对番茄灰霉病菌、番茄早疫病菌、小麦纹枯病菌、甘蓝黑腐病菌和西瓜果腐病菌的抑制作用较强,对番茄灰霉病菌的生长抑制率达86.25%;菌株B1的代谢产物对番茄灰霉病菌菌丝有致畸作用;菌株B1发酵上清液在离体叶片和活体植株上对番茄灰霉病具有良好的生防作用,其防治效果分别为68.80%和64.03%.根据形态特征、培养性状、生理生化特性和16S rDNA序列分析结果,将菌株B1初步鉴定为淡紫灰链霉菌Streptomyces lavendulae.通过正交试验筛选出菌株B1的液体发酵培养基组成为:葡萄糖15 g、玉米浆20g、NH4H2PO40.5 g、MgSO41.0 g、自来水1 000mL,pH 7.2～7.4.     

香蕉枯萎病拮抗菌的筛选及其作用机制研究

通过分离和筛选,从香蕉园或者其他果园的土壤中分离获得13株对香蕉枯萎病菌(Fusarium oxysporum f.sp.cubense)具有抑制作用的拮抗菌,并对部分拮抗菌抑制病菌菌丝生长和孢子萌发进行了试验。结果表明,拮抗菌株d4、d5、B3和p发酵液对香蕉枯萎病菌生长具有显著的抑制作用,在平板上产生的抑菌圈直径为21.75～34.75 mm,抑菌效果具有持续稳定性,对孢子萌发的抑制率为90.49%～97.18%;拮抗菌对病菌的作用表现为对菌丝的消融、菌丝细胞的泡囊化、抑制病菌分生孢子的萌发、孢子芽管的扭曲。     

内生菌B47的定殖能力及其对番茄青枯病的防治作用

从番茄茎分离的内生枯草芽孢杆菌菌株B47对番茄青枯病有较好的防治作用,利用该菌株的抗链霉素突变菌株,研究其在土壤和番茄植株根、茎中的定殖能力及其对番茄青枯病的防治作用。结果表明,枯草芽孢杆菌菌株B47可在土壤和番茄植株中定殖。B47施到土壤中后的15~45天,其数量逐步增加,45天后,其数量逐步下降。B47在土壤中的定殖能力随土壤的种类和土壤的处理情况而异。施入菜地土后的第45天,B47在非灭菌土中的数量是9.91×105cfu/g土壤干重,而在灭菌土中的数量是9.84×107cfu/g土壤干重。接种后,番茄植株根和茎中的B47数量,从苗期到结果期逐渐增加,但到了成熟期呈下降趋势。B47和番茄青枯病菌混合施入土壤后,随B47的数量增加番茄青枯病菌的数量显著降低。当番茄植株根和茎中B47的含量分别为1.17×104cfu/g鲜重和3.33×104cfu/g鲜重时,接种番茄青枯病菌后的第20天,对番茄青枯病的防治效果达79.79%。     

醚菌酯对假禾谷镰孢的抑制作用及对小麦茎基腐病的防效研究

 为了明确醚菌酯对假禾谷镰孢的抑制作用,本研究采用菌丝生长速率法和孢子萌发抑制法分别测定了醚菌酯对2019年从河南省13个地市分离的50株假禾谷镰孢的毒力。两种方法结果表明,醚菌酯对供试50株菌株的EC₅₀值范围分别在0.127 3~3.070 9 μg·mL^-1和0.001 3~0.070 9 μg·mL^-1,平均EC₅₀值为(1.304 1±0.804 2)μg·mL^-1和(0.017 4±0.017 0)μg·mL^-1。敏感性频率分布图显示,两种方法分别有80％(40株)和70％(35株)的菌株敏感性频率呈正态分布,其平均EC₅₀值分别为(1.135 2±0.531 2)μg·mL^-1和(0.011 4±0.006 3)μg·mL^-1,可作为假禾谷镰孢对醚菌酯的敏感性基线。方差分析结果表明,同一县市的假禾谷镰孢对醚菌酯的敏感性差异较大,EC₅₀值变化范围为0.545 2~2.156 4 μg·mL^-1和0.001 9~0.036 7 μg·mL^-1。聚类分析结果显示,河南省假禾谷镰孢对醚菌酯敏感性差异与菌株的地理来源无明显关联性。温室防效结果显示,小麦种子与醚菌酯悬浮种衣剂进行拌种处理可以起到一定防治效果,0.42 μL AI/2g处理防效最高,防治效果可达50.33％。本研究结果可为河南省假禾谷镰孢对醚菌酯的敏感性监测提供信息,同时为醚菌酯对小麦茎基腐病的防治提供理论依据。     

香蕉枯萎病拮抗菌贝莱斯芽胞杆菌的筛选鉴定及其生物学特性

香蕉枯萎病是目前香蕉产业面临的毁灭性病害,目前尚无特别有效的防治药剂.为发掘香蕉枯萎病的生防菌资源,本研究通过初筛和复筛获得两株对香蕉枯萎病菌具有较强拮抗活性的菌株Blz67和Blz02.依据形态学观察及生理生化测试结果,并结合16S rRNA和gyrA基因序列分析,将两株拮抗菌鉴定为贝莱斯芽胞杆菌Bacillus v...     

Ecology of pitaya stem rot caused by Gilbertella persicaria and its biological control by phyllosphere bacteria

Gilbertella persicaria stem rot is a disease that causes rotting in the stem nodules and fruits of pitaya. Here, we aimed to study the ecology of G. persicaria and its biological control using several Bacillus subtilis strains isolated from the phyllosphere. Sporangiospores of G. persicaria were detected on different parts of the plant, with maximum density (c.239.9 propagules/cm²) found on the petals after flowering, and spore germination was observed to be considerably affected by humidity. Furthermore, the study revealed that an incision wound of at least 2 mm depth was necessary for infection by the pathogen to the stem nodule, and exposure to high temperatures (50°C) accelerated disease incidence, by disrupting resistance to the spread of the pathogen. Additionally, biological control of G. persicaria was effectively achieved by inoculation with B. subtilis strains isolated from pitaya stem nodules. Intriguingly, treatment with antagonistic bacteria reduced stem rot incidence to zero (bacterial suspension: PNB-5, PNB-7, and PNB-93; culture filtrate: PNB-7, PNB-93, and PNB-95), equivalent to that achieved by fungicide application in both prophylactic and simultaneous treatments. Collectively, this is the first study to demonstrate the ecology of G. persicaria and to show the potential applicability of phyllosphere bacterial strains for biological control of G. persicaria in pitaya, which could help develop effective integrated disease management strategies for the control of pitaya stem rot.