球孢白僵菌的侵染特性及应用研究进展

球孢白僵菌是一种重要的虫生真菌,具有致病力强、侵染范围广、安全无污染等优点,其制剂可作为一种真菌类杀虫剂应用于农林业害虫的防治,也可用于人工生产中药材僵蚕。本文综述了球孢白僵菌的培养性状、侵染特性、应用生产和存在的问题,并提出了发展对策,为球孢白僵菌的进一步开发应用提供参考。     

Infection of Blissus antillus (Hemiptera: Lygaeidae) Eggs by the Entomopathogenic Fungi Metarhizium anisopliae and Beauveria bassiana

This study determined the pathogenicity and virulence of Beauveria bassiana and Metarhizium anisopliae to eggs of the chinch bug Blissus antillus (Hemiptera: Lygaeidae). Eggs were inoculated under laboratory conditions by immersion in concentrations of 1 × 10⁴ and 5 × 10⁶ conidia/ml. Inoculated eggs were kept under controlled conditions. Evaluations were carried out daily for 20 days. M. anisopliae isolates were highly virulent to eggs, even at 1 × 10⁴ conidia/ml. All B. bassiana isolates tested were considered to be of low virulence or avirulent. The most virulent isolate tested was ESALQ 818 (M. anisopliae), which caused 96.7% infection, when eggs were immersed in suspensions of 1 × 10⁴ conidia/ml. Conidial production on infected eggs was observed to be highest for M. anisopliae isolate CG144, with a mean value of 11.6 × 10⁵ conidia/ml/egg. Infection of Blissus eggs oviposited on plant stems was greater when M. anisopliae isolate CG144 was formulated in mineral oil (63.5% mortality) than when formulated in Tween 80 (27.1% mortality).     

Host selection and survival of the parasitoidEncarsia formosa on greenhouse whitefly,Trialeurodes vaporariorum, in the presence of hosts infected with the fungusAschersonia aleyrodis

Successful control of greenhouse whitefly may be achieved by complementary activity of the parasitoidEncarsia formosa and the fungusAschersonia aleyrodis. One way to obtain an additive mortality effect of both entomopathogen and parasitoid would be achieved by the selection of healthy hosts by the parasitoid and rejection of fungus-infected hosts. Third and fourth instar larvae ofTrialeurodes vaporariorum which had been treated with a spore suspension ofA. aleyrodis 0, 4, 7, 10 or 14 days beforehand, were presented to female parasitoids. The parasitoids adopted the oviposition posture on untreated hosts as well as on treated hosts, irrespective of the different stages of infection in the hosts. However, significantly more hosts were parasitized byE. formosa in the control treatment than in the fungal treatment. The parasitoids offered treated hosts, showed rejection behaviour after probing on hosts showing detectable signs of infection (containing hyphal bodies or mycelium in the haemolymph). For instance, when hosts were offered seven days after spore treatment, the parasitoids showed an oviposition posture on a total of 83 (95.4%) out of 87 infected larvae, but laid only 4 eggs (4.6%). In contrast, on 48 (94.1%) out of 51 noninfected (or showing no detectable signs of infection) hosts an oviposition posture was adopted and 40 eggs (78.4%) were found after dissection. When infected hosts were encountered the oviposition posture lasted less than 1′40″ while rejection of non-infected hosts occurred after more than 1′40″. Other experiments were carried out offering treated hosts for 24 h to the parasitoids. The hosts were dissected afterwards. Again, significantly more eggs were laid in the non-infected hosts. When hosts were parasitized shortly after fungal spore treatment they were colonized by the fungus and the parasitoids did not develop. Transmission of the entomopathogen after probing infected hosts was observed to a limited extent. In conclusion,A. aleyrodis andE. formosa can be used together in a glasshouse situation. The parasitoid will be most effective when introduced more than seven days after application ofA. aleyrodis, because from that time onwards it is able to detect and reject fungus-infected hosts.     

Imbibitional damage in conidia of the entomopathogenic fungi Beauveria bassiana, Metarhizium acridum, and Metarhizium anisopliae

When dried organisms are immersed in water, rapid imbibition may cause severe damage to plasma membranes; in unicellular organisms, such damage is usually lethal. This study investigated effects of water activity (dryness) of organisms and immersion temperature on imbibitional damage in three insect pathogenic fungi. Conidial powders of Beauveria bassiana (Bb), Metarhizium anisopliae (Ma) and Metarhizium acridum (Mac) were dried/hydrated to a broad range of water activities (a_w) (0.023–0.961) prior to immersion in water at 0.5–33 °C. Imbibitional damage in conidia of each fungus occurred rapidly, with no differences in viabilities observed following immersion for 2 vs. 60 min. Damage increased with decreasing water activity of the conidia and decreasing temperature of the immersion water. Dry (a_w  0.333) Metarhizium spp. conidia were highly susceptible to imbibitional damage, with viability declining to 5% after immersion at 0.5 °C and 63% following immersion at 15 °C. Germination of the driest Ma conidia was reduced to 66% after treatment at 25 °C. In contrast, Bb was highly tolerant to damage, with significant reductions in viability (to levels as low as 43–65%) occurring only when dry conidia were immersed at 0.5 °C. Damage was prevented when conidia were slowly rehydrated by humidification prior to immersion and immersion temperature was increased to 33–34 °C; germination of all fungi was 94% under these optimal conditions. However, immersion of the driest Bb, Ma, and Mac powders in warm water (33 °C) also resulted in high viabilities (95%, 89%, and 94%, respectively), and slow-rehydrated conidia also retained high viability (87%, 92%, and 83%, respectively) after immersion in ice-cold water (0.5 °C). Formulation of conidia in pure (non-emulsifiable) paraffinic oil provided considerable protection from imbibitional damage. This study underscores a need for establishing standard protocols for preparing aqueous suspensions of sensitive fungi for both research and commercial applications.     

Whey for mass production of Beauveria bassiana and Metarhizium anisopliae

Spore production of Beauveria bassiana and Metarhizium anisopliae was studied in a novel whey-based culture media. Spore yield and viability were determined for two B. bassiana (GHA-726 and CA-603) and two M. anisopliae (CA-1 and IMI 330189) isolates following production in three whey-based systems: solid, liquid, and a diphasic production system. Our study indicated that whey permeate can be used effectively for production of spores of entomopathogenic fungi. However, spore yield and viability were significantly influenced by fungal isolate, whey concentration, and the type of production process used. Under the conditions defined in the present study, spore yields ranging from 1.3 × 10⁹–10 × 10¹¹ spores l⁻¹ of whey medium could be obtained depending on the strain and production process used. Our study revealed that spores produced by all strains in whey-based solid and liquid media showed between 73–99 % viability; germination rates were comparable with those obtained using the standard SDA medium. In the two-stage production process, the viabilities of conidia produced by GHA-726, CA-603, and CA-1 were 35–86, 32–98, and 6–29 %, respectively; viability was correlated with whey concentration and isolates. Whey permeate can be used as a growth substrate for mass production of biocontrol fungi. We hypothesize that spore yield and viability could be improved by careful selection of whey content in the medium, incorporation of critical additives and optimization of culture conditions.     

一株感染家蚕的高致病性白僵菌的筛选及发酵条件优化

【背景】球孢白僵菌是一种重要的昆虫病原真菌,通过侵染幼蚕可制备白僵蚕。白僵蚕中的生物活性物质在医疗、保健品及化妆品行业有着广泛的应用。【目的】从7株不同来源的白僵菌中筛选获得高毒力白僵菌并优化其发酵条件,为制备白僵蚕提供优质的菌种资源。【方法】从不同白僵蚕体内分离获得7株白僵菌菌株(SDJC-1、SDJC-2、SDJC-3、GXHC-1、SDND-BB、AT-3006和SQJC-1),通过生物学特性观察、产蛋白酶和几丁质酶活力分析及对家蚕的致死力等研究,筛选得到一株致病力高、性状优异的白僵菌株,并对其最适发酵条件进行探索。【结果】菌株SDJC-3的生物学性状优异,产孢量较高,家蚕致死率达75%,其制备的白僵蚕成品个头大且饱满,横截面丝腺环清晰,品质较好。通过对菌株SDJC-3进一步进行发酵优化,发现其最适生长温度为27℃、最优发酵转速为180 r/min、最适的发酵液体积占比为1/5 (250 mL培养瓶)。【结论】本研究将为人工利用白僵菌制备白僵蚕及提高其产量和品质提供理论基础。     

球孢白僵菌种内比较线粒体基因组学分析

【目的】明确球孢白僵菌种内线粒体基因组的分化程度。【方法】从GenBank下载已知的球孢白僵菌6个菌株线粒体基因组序列,详细分析基因组的组成结构,比较外显子区、内含子区和基因间区的碱基变异情况,分析菌株间的系统发育关系。【结果】球孢白僵菌不同菌株的线粒体基因组大小为28.8–32.3 kb,都有14个常见的核心蛋白编码基因、2个rRNA基因和25个tRNA基因,具有很强的共线性关系。但是,不同菌株含有的线粒体内含子数目存在差异(2–5个/菌株),在cox1、cox2和nad1基因中表现出内含子插入/缺失多态性,这是导致线粒体基因组大小变化的主要因素。对外显子、内含子和基因间区的碱基变异情况进行分析,发现内含子和基因间区相对变异较大,而外显子区相对变异较小。系统发育分析发现,这些球孢白僵菌菌株以很高的支持度聚在一起,具有相同内含子分布规律的菌株也具有较近的聚类关系。【结论】本研究首次报道球孢白僵菌因内含子数目不同、插入缺失突变和单核苷酸变异等在线粒体基因组上表现出较大程度的遗传分化,为认识真菌种内线粒体基因组分化提供了新的证据。     

Horizontal transfer and hypovirulence associated with double-stranded RNA in Beauveria bassiana

Beauveria bassiana strains from different hosts and geographic origins were assayed for the presence of double-stranded RNA (dsRNA). Two of them (15.4 %) showed extra bands, with approximately 4.0–3.5 kb and 2–0.7 kb, respectively, after electrophoretic separation of undigested nucleic acids. Virus-like particles were approximately 28–30 nm diam. The dsRNA was maintained after conidiogenesis (vertical transmission) and was transmitted horizontally by hyphal anastomosis. Strains purged of dsRNA obtained after cycloheximide treatment showed increased conidial production when compared with strains carrying dsRNA particles. Bioassays demonstrated hypovirulence associated with dsRNA. The mean mortality against the insect Euschistus heros was reduced in strains containing dsRNA when compared with the isogenic dsRNA-free ones.     

Evaluation of the Entomopathogenic Fungi Beauveria bassiana and Paecilomyces fumosoroseus for Microbial Control of the Silverleaf Whitefly, Bemisia argentifolii

Collaborative research was conducted at the USDA-ARS Subtropical Agricultural Research Center in southern Texas to assess the microbial control potential of Beauveria bassiana and Paecilomyces fumosoroseus against Bemisia whiteflies. Laboratory assays demonstrated the capacity of both pathogens to infect Bemisia argentifolii nymphs on excised hibiscus leaves incubated at relative humidities as low as 25% at 23 ± 2°C (ca. 35% infection by B. bassiana and P. fumosoroseus resulted from applications of 0.6–1.4 × 10³ conidia/mm² of leaf surface). In small-scale field trials using portable air-assist sprayers, applications at a high rate of 5 × 10¹³ conidia in 180 liters water/ha produced conidial densities of ca. 1–2.5 × 10³ conidia/mm² on the lower surfaces of cucurbit leaves. Multiple applications of one isolate of P. fumosoroseus and four isolates of B. bassiana made at this rate at 4- to 5-day intervals provided >90% control of large (third- and fourth-instar) nymphs on cucumbers and cantaloupe melons. The same rate applied at 7-day intervals also provided >90% control in zucchini squash, and a one-fourth rate (1.25 × 10¹³ conidia/ha) applied at 4- to 5-day intervals reduced numbers of large nymphs by >85% in cantaloupe melons. In contrast to the high efficacy of the fungal applications against nymphs, effects against adult whiteflies were minimal. The results indicated that both B. bassiana and P. fumosoroseus have strong potential for microbial control of nymphal whiteflies infesting cucurbit crops.     

Effect of different isolates of Beauveria bassiana on field populations of Lygus hesperus

Lygus hesperus (Knight) (Hemiptera: Miridae) is a particularly damaging pest of many crops in the Western United States. Current control tactics are chemically based and there is some concern over resistance building up in populations. Based on previous laboratory studies conducted in California and Mississippi, USA, two new isolates of the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin (Deuteromycotina: Hyphomycetes) were selected for field-testing against L. hesperus in California. Alfalfa plots were treated with one of three isolates of B. bassiana (a commercial isolate, an isolate from CA (WTPB2) or an isolate from MS (TPB3)) or the chemical pesticide Warrior T. More than 75% of the adults collected from plots 3 days after application with B. bassiana were infected but no differences in percentage infection occurred among fungal treatments. In addition, approximately 30% of the insects collected from control plots or plots treated with Warrior T were also infected. PCR analysis using SSR markers revealed that the isolate causing most of the infections in fungus treated plots was the isolate applied. A mix of infections was found in control plots and plots treated with Warrior T. Despite high levels of infection, no significant reductions of adult populations occurred until 10–14 days after application when plots treated with Warrior T or B. bassiana had about half the numbers of adult L. hesperus as the control plots.     

草菇VvLaeA调控球孢白僵菌的生长发育

食用真菌草菇[Volvariella volvacea(Bull.ex.Fr.)Sing.]VvLaeA在调控真菌发育方面的功能并不清楚。本研究在对草菇VvLaeA进行生物信息学分析基础上,通过聚合酶链式反应(polymerase chain reaction,PCR)的方法将超量表达启动子Vvgpd和草菇VvlaeA基因的开放阅读框(open reading frame,ORF)进行融合,并将融合片段克隆入pK2(bar)载体。采用农杆菌介导的转化方法将重组载体pK2(bar)-OEVvlaeA转入球孢白僵菌中进行表达,测定转化子的菌株发育情况。结果表明,草菇VvLaeA与其他真菌的蛋白同源性较低;和野生型相比,转化菌株的菌落直径显著增大,色素减少,分生孢子产量和萌发率均显著下降,对胁迫反应的敏感性增强。进一步研究发现,转化菌株分生孢子的细胞壁结构成分发生改变,和分生孢子发育相关基因的表达被显著下调。提示草菇VvLaeA能提高球孢白僵菌菌株的生长速率,而负调控色素沉积和分生孢子发育,这为草菇基因功能鉴定提供了启示。     

球孢白僵菌对烟蚜茧蜂生命参数及控害效果的影响

在室内评价了球孢白僵菌对烟蚜茧蜂生命参数及控害效果的影响。分别在烟蚜茧蜂寄生桃蚜后不同时间进行高剂量(1900孢子/mm2)接菌,检测蚜虫感病率和寄生蜂形成的僵蚜率及僵蚜出蜂率。结果表明,球孢白僵菌对僵蚜率和僵蚜出蜂率的影响随接菌时间不同而变化。在烟蚜茧蜂寄生前1d、寄生当天和寄生后3d接菌,蚜虫感病率分别为59.6%、56.2%和34.8%;与对照相比,僵蚜率分别下降94%、59%和47%,僵蚜出蜂率分别减少83%、54%和49%。在寄生后5d或7d接菌,僵蚜率和僵蚜出蜂率不受明显影响,但蚜虫感病率降低到8.2%以下。对蚜尸内白僵菌菌体含量检测表明,随着烟蚜茧蜂寄生后接菌时间的推移,菌体数量迅速下降。寄生蜂寄生后5d或7d接菌,蚜尸内几乎检测不到菌体。直接喷雾接菌烟蚜茧蜂,成蜂寿命缩短4d左右,且81.8%的蜂尸受白僵菌感染。接菌后的寄生蜂对蚜虫寄生率几乎无影响,但寄生蜂在蚜虫体内的存活时间缩短了27.8%。     

球孢白僵菌对烟蚜茧蜂生命参数及控害效果的影响

在室内评价了球孢白僵菌对烟蚜茧蜂生命参数及控害效果的影响。分别在烟蚜茧蜂寄生桃蚜后不同时间进行高剂量（1900孢子/mm^{2）接菌,检测蚜虫感病率和寄生蜂形成的僵蚜率及僵蚜出蜂率。结果表明,球孢白僵菌对僵蚜率和僵蚜出蜂率的影响随接菌时间不同而变化。在烟蚜茧蜂寄生前1d、寄生当天和寄生后3d接菌,蚜虫感病率分别为59.6%、56.2%和34.8%;与对照相比,僵蚜率分别下降94%、59%和47%,僵蚜出蜂率分别减少83%、54%和49%。在寄生后5d或7d接菌,僵蚜率和僵蚜出蜂率不受明显影响,但蚜虫感病率降低到8.2%以下。对蚜尸内白僵菌菌体含量检测表明,随着烟蚜茧蜂寄生后接菌时间的推移,菌体数量迅速下降。寄生蜂寄生后5d或7d接菌,蚜尸内几乎检测不到菌体。直接喷雾接菌烟蚜茧蜂,成蜂寿命缩短4d左右,且81.8%的蜂尸受白僵菌感染。接菌后的寄生蜂对蚜虫寄生率几乎无影响,但寄生蜂在蚜虫体内的存活时间缩短了27.8%。}     

Whorl and pollen-shed stage application of Beauveria bassiana for suppression of adult western corn rootworm

The corn rootworm complex is the most damaging insect pest of corn (Zea mays L.). This study was conducted to determine the efficacy of whorl and pollen-shed stage applications of a granular formulation of Beauveria bassiana (Balsamo) Vuillemin for control of adult western corn rootworm (Diabrotica virgifera virgifera Le Conte). The effect of application time (whorl-stage, pollen-shed) and plant surface exposed (leaves and leaf collars; silks; leaves, leaf collars, and silks) on level of beetle fungal infection were investigated. In addition, the number of colony forming units of B. bassiana in the corn leaf collar area was quantified. In the three years (1998–2000) of the study, application of B. bassiana at whorl-stage did not significantly increase beetle fungal infection. Beauveria bassiana applied to plants at pollen-shed in 1998 resulted in a significant increase in beetle infection with 51% of beetles from treated plants infected and 6.0% from control plants. Similar applications at pollen-shed in 1999 and 2000 resulted in very low infection levels. Beauveria bassiana application at pollen-shed stage significantly increased the number of colony forming units per leaf collar during all years of the study. Beetle infection with B. bassiana did not differ consistently among plant surface to which beetles were exposed for either application. Increased fungal load in leaf collars was not correlated with increased levels of adult infection. Increased rates of B. bassiana and application when beetles are present on the plants are likely needed to significantly increase infection rates.     

白僵菌超低容量油剂林间应用对生物多样性的影响

2001～2003年在福建省云霄县进行了白僵菌超低容量油剂林间防治马尾松毛虫后对生物多样性的影响研究(包括使用前后的物种丰富度S、个体数N、多样性指数H'、均匀度指数R和优势度指数D等).结果表明,未防治区和白僵菌油剂防治区的物种数分别为473种和392种,而化学防治区的物种数只有266种;白僵菌油剂防治区天敌和害虫个体数与未防治区的比例相近,分别为0.1049:1和0.1051:1,明显高于化学防治区(0.0558:1);化学防治和白僵菌油剂防治均降低了物种的丰富度和多样性,同时也增强了物种的优势度,但化学防治区与未防区的差异显著,白僵菌油剂防治区与未防区的差异不显著,尤其对天敌和非目标昆虫无显著影响.     

Inoculation of coffee plants with the fungal entomopathogen Beauveria bassiana (Ascomycota: Hypocreales)

The entomopathogenic fungus Beauveria bassiana was established in coffee seedlings after fungal spore suspensions were applied as foliar sprays, stem injections, or soil drenches. Direct injection yielded the highest post-inoculation recovery of endophytic B. bassiana. Establishment, based on percent recovery of B. bassiana, decreased as time post-inoculation increased in all treatments. Several other endophytes were isolated from the seedlings and could have negatively influenced establishment of B. bassiana. The recovery of B. bassiana from sites distant from the point of inoculation indicates that the fungus has the potential to move throughout the plant.     

球孢白僵菌响应氧化胁迫的分子机制研究进展

球孢白僵菌作为模式丝状真菌,以分生孢子、菌丝体、虫菌体等多种形态存在,在真菌孢子发育、寄主与宿主互作的研究中具有重要意义。同时,球孢白僵菌又是一类广泛应用的真菌杀虫剂,对森林防护和农业生产具有实际应用价值。球孢白僵菌的相关基因被敲除后,突变体响应氧化胁迫,孢子发育和毒力会发生改变。本文综述了近年来球孢白僵菌在响应氧化胁迫方面的研究进展,为丝状真菌氧化胁迫信号途径的研究提供参考。     

二种交配型球孢白僵菌对亚洲玉米螟的生态控制作用

利用生物种间互做关系抑制农业害虫的暴发是生物防治的重要手段。为探讨二种交配型内共生球孢白僵菌与玉米之间的互惠关系及其形成的共生体在亚洲玉米螟控制中的生态效应,以玉米为宿主植物,以球孢白僵菌孢子悬浮液进行灌根,在温室内构建了二种交配型(MAT1-1-1型,B5;MAT1-2-1型,B2)球孢白僵菌-玉米共生体,并研究了共生体对玉米的生长、对亚洲玉米螟的产卵选择和幼虫发育及其对球孢白僵菌生物学特性的影响。结果显示:通过叶片离体培养、ITS基因和交配型基因MAT检测,均能检测到白僵菌的内生定殖;MAT1-2-1型B2菌株定殖检出率高,MAT1-1-1型B5菌株在混合型接种中定殖有优势。回收后的球孢白僵菌菌落直径和毒力无显著性变化,但其产孢量都显著提高其中回收B5处理组来源菌株的产孢量提高最显著。接种过球孢白僵菌的玉米植株地上部生长速度、生物量和地下根系生物量均优于对照组,其中根系干重明显增加,而地上植株干重也相对增加。MAT1-1-1型菌株B5对共生体玉米植株地上高度促生长贡献明显;MAT1-2-1型菌株B2对共生体玉米植株地下干重增加贡献明显。总体上球孢白僵菌内生定殖对玉米地下根系生物量影响大于对地上植株生物量的影响。在产卵选择性试验中,各处理组亚洲玉米螟的产卵量显著少于对照组。共生体对亚洲玉米螟产卵具有明显的趋避作用,MAT1-2-1型菌株B2对产卵的趋避作用明显,而MAT1-2-1型菌株B5的趋避作用较弱。在人工接种幼虫的试验中,处理组回收的亚洲玉米螟幼虫存活率均显著低于对照组,其中,B5组回收幼虫的存活率最低,仅为38.33%;处理组的化蛹率与对照组差异不显著,但B5组的回收幼虫化蛹率显著低于B2组和对照组,仅为34.77%,这说明MAT1-1-1型B5菌株对玉米螟幼虫发育抑制最明显。上述结果表明,不同交配型球孢白僵菌内生定殖效率有差异,在经过内生定殖后在产孢量方面有显著性提高,两个交配型菌株在联合应用时具有协同增效作用;两个交配型菌株均能够通过内生定殖与玉米形成共生体并促进玉米植株的生长,这显示球孢白僵菌和玉米之间已经建立具有互惠关系的共生体。这种共生体通过趋避亚洲玉米螟产卵、抑制幼虫存活和降低化蛹率等方面的潜力虽然不一样,但都有助于对亚洲玉米螟的可持续生态防治,也证明了共生体的建成有效提高了玉米的生态适应性,为利用球孢白僵菌内共生性实施亚洲玉米螟防控提供了新思路。     

Hemocytic defense response to the entomopathogenic fungus Beauveria bassiana in the migratory grasshopper Melanoplus sanguinipes

Hemocytic defense response of the migratory grasshopper, Melanoplus sanguinipes (Fab.), to conidia of the white muscardine fungus, Beauveria bassiana (Bals.) Vuill., was studied using phase-contrast photomicroscopy, hemocyte counting and hemocyte aggregation or nodule formation. Grasshoppers were injected with an aqueous suspension of conidia. Adherence of B. bassiana conidia to granulocytes occurred within 10 min and the conidia were encapsulated by these hemocytes 6 h postinjection. Hemocytopenia was accompanied by nodule formation after injection of B. bassiana conidia into grasshoppers. The conidia germinated within the nodules and grew into hyphal forms within the hemolymph 12 to 24 h postinjection. We conclude that B. bassiana competes well with nodule formation by hemocytes of M. sanguinipes and often escapes complete encapsulation.

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Résumé Le mécanisme de défense du hémocyte de la sauterelle migratrice Melanoplus sanguinipes envers le champignon pathogène Beauveria bassiana a été etudié a l'aide du photomicroscope a contrase de phase, par dénombrement des hemocytes, ainsi que des nodules formées par l'agrégation des hémocytes. L'adhérence des conidies de B. bassiana aux hemocytes a été observée 10 min après l'injection et leur encapsulement après 1 h. Une baisse des taux d'hémocytes a fait suite a la formation de nodules apres l'injection de conidies dans les sauterelles. Après le déclin initial du taux des hémocytes, une hausse s'est produite dans les sauterelles auquelles on a injecté 10⁶ conidies. Les conidies ont germé dans les nodules et la croissance du mycélium s'est produite dans l'hémolymphe 24 h après avoir injecté. Cette étude a revelé que M. sanguinipes peut exercer temporairement un mécanisme de défense cellulaire contre des conidies fongiques a une concentration de 10⁶ conidies.

     

球孢白僵菌Hog1 MAPK同源基因BbHog1的克隆及特征分析

根据几种丝状真菌Hog1 MAPK的保守氨基酸序列设计简并引物,从昆虫病原真菌球孢白僵菌中扩增出MAPK同源基因的部分片段,然后利用YADE法延伸该片段的上、下游邻接序列,获得MAPK编码基因的全长序列,命名为BbHog1。序列分析表明,该基因编码358个氨基酸的多肽,推测分子量为40.99kDa,等电点为5.49。BbHog1含有MAPK保守的蛋白激酶激活域(TGY),序列与粗糙脉孢霉os-2(AF297032)、烟曲霉OSM1(XM_747571)、隐球酵母HOG1(AF243531)和酿酒酵母Hog1(Z73285)等Hog1 MAPK高度同源,相似性分别为94%、89%、83%和80%。系统聚类结果表明,BbHog1与酵母Hog1 MAPK同源。Southern杂交表明,BbHog1在球孢白僵菌基因组中以单拷贝形式存在。Northern分析表明,BbHog1在高渗、亚高温和营养胁迫等条件下的表达明显升高。由此推测,BbHog1基因可能与球孢白僵菌对逆境胁迫的适应性调节密切相关。