磷酸钠对粉红单端孢的离体抑菌作用研究

以引起果蔬采后病害的重要病原物粉红单端孢(Trichothecium roseum)为研究对象,探究离体条件下不同浓度磷酸钠对T. roseum菌丝生长和孢子萌发的抑制作用及其初步机理。结果表明,不同浓度磷酸钠处理均可抑制T. roseum菌丝生长和孢子萌发,且随着处理浓度的增加,抑制效果增强。此外,2.0 mg/mL磷酸钠处理降低了T. roseum胞外相对电导率,提高了胞外丙二醛和可溶性蛋白含量,降低了胞外可溶性糖含量。扫描电镜结果显示,2.0 mg/mL磷酸钠处理的孢子表面粗糙且发生皱缩。因此,离体条件下磷酸钠能够抑制T. roseum生长,其抑菌机理与细胞膜结构的破坏有关。     

枯草芽孢杆菌B_1、B_2液对“黄河蜜”瓜采后黑斑病和粉霉病的抑制效果

研究了枯草芽孢杆菌B1、B2的活菌液、代谢液对“黄河蜜”甜瓜采后黑斑病和粉霉病的抑制效果。离体条件下,B1、B2活菌液对黑斑病菌(A.alternata) 的抑制率分别达到100 %和94 %,而对粉霉病菌(T.roseum)的抑制率均达到100 %。离体条件下,B1、B2活菌液均能显著抑制“黄河蜜”甜瓜采后黑斑病和粉霉病的侵染和扩展。B1、B2代谢液显著抑制粉霉病的扩展,但对黑斑病的扩展无抑制效果。     

Biological control of botrytis leaf blight of onion byGliocladium roseum applied as sprays and with fabric applicators

Gliocladium roseum (5×10⁶ conidia ml^–1) and chlorothalonil (Bravo 500) were compared in two field tests for effectiveness in suppressing leaf blight caused byBotrytis squamosa in cooking onions. The biological control agent and fungicide were applied with sprayers and with specially designed fabric applicators that were mounted interchangeably on an aluminium carriage with bicycle wheels. In the applicators, inoculum and fungicide gravitated from a reservoir down curtains of denim strips and onto portions of onion leaves contacted by the strips. Initial applications were timed using a leaf blight forecasting system (BOTCAST) and three or four subsequent applications were made at weekly intervals. When compared to water checks,G. roseum applied as sprays or by applicators reduced density of leaf spots by about 50–58% during middle and late stages of epidemics. The antagonist was about half as effective as chlorothalonil in suppressing density of spots, regardless of application method. The applicators delivered inoculum in similar densities to proximal and distal halves of leaves, and used at least 35% less volume of inoculum compared to the sprayers. Density of inoculum on leaves treated by applicators was about the same as in spray-treated leaves when canopies were sparse, but less when canopies were dense. It is concluded thatG. roseum has good potential for controlling leaf blight sufficiently to avoid economic yield losses.     

几种生防放线菌离体颉颃作用测定

采用菌饼对峙法测定4种放线菌对7种病原真菌的离体颉颃作用。结果发现,SC1,SC11和SE2菌株对所有靶标菌均有不同程度的抑制作用。菌株SC11对各供试靶标菌均有良好稳定的抑制作用,接种后5 d测量靶标菌菌落半径均小于4 mm,菌丝日生长速率低于0.75 mm/d。菌株SE2对粉红聚端孢、立枯丝核菌、番茄叶霉菌的抑制作用比其它3种放线菌要好,抑制率高达100%。在所有测定的靶标菌中,番茄灰霉菌、粉红聚端孢菌、西瓜枯萎菌、立枯丝核菌是较易于被放线菌抑制的靶标菌。显微观察发现受,SC1,SC11,SE2抑制后,靶标菌菌丝出现不同程度的畸形。     

杏贮藏过程中主要致病菌的分离与鉴定

为有效控制杏果采后贮藏中的主要致病菌,对贮藏中腐烂小白杏果实上的病菌进行了分离与鉴定。分离并筛选得到了3种主要霉菌,经过形态结构鉴定和显微镜观察,确定为粉红单端孢霉（Trichothecium roseum）、链格孢霉（Alternaria alternata）和天门冬拟茎点霉（Phomopsis asparagi）。经过回接发现,该3种霉菌能使健康杏果致病,且病状与自然发病一致,从这些病斑中又分离得到了相同的霉菌,从而确定该3种霉菌为小白杏采后的主要致病菌。     

Characterization of the host range and sensitivity to fungicides of Trichothecium spp. associated with fruit rot in the field and in storage

During 2017–2019, we observed Trichothecium spp. causing fruit rot in the field and in storage. This study was conducted to examine morphological differences of the species from different hosts, reveal the species’ potential host range, and evaluate the efficacy of five fungicides. Six strains of Trichothecium spp. isolated from nectarine, peach and walnut were selected. Although the colony morphology, mycelial growth rate and spore size differed among hosts, phylogenetic analysis based on the internal transcribed spacer and part of the 5ʹ end of the β-tubulin gene showed that all tested strains belonged to Trichothecium roseum. For its host range, 23 kinds of fruit were examined using T. roseum strain YT-1 as an inoculum; 10 kinds of fruit, including pear, apple, mango, Chinese chestnut, pepino melon, fig and durian, were susceptible to T. roseum, with minimum inoculation concentrations ranging from 10⁴ to 10⁵ spores/ml. The fungicides that most effectively inhibited the six isolates were fluazinam and fludioxonil, with EC₅₀ values of 0.07–0.1 and 0.01–0.04 μg/ml, respectively, followed by difenoconazole (0.81–2.96 μg/ml), boscalid (5.43–13.51 μg/ml) and azoxystrobin (9.18–27.25 μg/ml). Improvement of the shelf life of nectarines held in plastic trays was explored using allyl isothiocyanate (AITC) against T. roseum YT-1. The application of 10 μl/L AITC significantly suppressed disease symptoms. The findings provide useful information for future disease emergency management in the field and for food preservation.     

粉红粘帚霉67-1菌株寄生核盘菌研究

 用诱捕法从海南乐东县菜园土壤中获得一株对核盘菌菌核具有强寄生能力的粉红粘帚霉(Gliocladium roseum)菌株67-1,寄生频率为100%。该菌的PDA平板回接核盘菌菌核,一周后寄生率可达100%。对峙培养发现其对核盘菌有明显的抑菌带。保湿条件下,该菌孢子在24h内成功侵入核盘菌菌核。切片显微观察证明该菌能高效侵染菌核,造成组织溃解。寄生过程中菌核内蛋白组成发生明显变化。这一菌株在22~35℃均能很好生长,菌丝及产孢最适温度为24℃,产孢量大。认为这一菌株具有良好的菌核病生防应用潜力。     

枣果贮藏期红粉病菌鉴定及环境因子对其分生孢子萌发的影响

 在山西省临县、太谷县发现枣贮藏期红粉病,发病初期果实表面出现圆形或椭圆形的白色絮状霉点,后期形成较厚粉状霉层。从病样中分离获得2株代表性菌株,通过病原菌分离培养、致病性测定、形态学特征及ITS序列特征分析,确定引起枣贮藏期红粉病的致病菌为粉红单端孢(Trichothecium roseum)。适合该病菌分生孢子萌发的温度为20℃~25℃,相对湿度为大于75%,pH=4~10,致死温度为48℃、处理10 min。适宜芽管生长的温度为20℃~25℃,相对湿度为大于75%,最适pH=6。本研究结果可为枣贮藏期红粉病的诊断和防治措施的制定提供理论依据。     

粉红粘帚霉G-019浅盘发酵工艺的研究

对粉红粘帚霉G-019浅盘发酵工艺进行了研究，为提高生产孢子产量，进行了固态发酵基质、营养液成分的筛选和含量的单因素实验。结果表明最佳发酵工艺为：固态发酵基质为麸皮75%，玉米粉15%，啤酒糟10%，营养液为糖蜜2%，磷酸氢二钾0.15%,硫酸镁0.5%，料液比1：1，在此条件下发酵10d孢子数可达1.07*10^10CFU/g。     

粉红聚端孢菌胞外几丁质酶纯化、特性及抗菌活性

 粉红聚端孢菌(Trichothecium roseum)在SMCS中恒温摇床(200 r/min,28℃)上培养12 d,诱导产生了大量的胞外几丁质酶。培养滤液经(NH₄)₂SO₄分级沉淀、DEAE-Sepharose FF阴离子交换柱层析和CM-Sepharose FF阳离子交换柱层析获得了SDS-PAGE纯的胞外几丁质酶,分子量约为39k Da。几丁质酶最适作用温度为40℃,最适pH范围为4.0~7.0。抗菌活性显示,纯酶对供试病原菌都有不同程度的抑菌作用,其中对棉花黄萎菌的抑制作用最强。