茶轮斑病病原菌的分离鉴定及其拮抗菌筛选

从湖南省武陵山区4个茶叶种植基地采集茶轮斑病病叶，采用组织分离法对病原菌进行分离，通过致病性、形态学、分子生物学鉴定，确定病原菌为茶拟盘多毛孢(Pseudopestalotiopsistheae)。以病原菌为指示菌，采用平板对峙法从病叶中筛选得到效果最佳的拮抗菌kc–6，抑菌率为79.86%，经鉴定为解淀粉芽孢杆菌(Bacillus amyloliquefaciens)。分析拮抗菌对病原菌菌丝生长的抑制效果，对茶树离体叶片的防效、继代培养稳定性以及对10种作物病原菌的拮抗效果进行评价。结果表明：拮抗菌kc–6可使茶轮斑病病原菌菌丝萎缩变细，部分膨大；其发酵液原液、稀释10倍液和100倍液对茶树离体叶片的防效分别为72.73%、52.55%、3.03%；连续转接培养25次后的抑菌率仍保持70.33%;kc–6菌株对10种作物病原真菌均有抑制效果，其中对茄子褐纹病菌(Phomopsis vexans)、黄瓜枯萎病菌(Phytophthora melonis)、茭白镰刀菌(Fusarium graminearum)的抑制效果较好，抑制率分别为83.00%、80.00%、76.00%。     

茶树腐皮镰刀菌拮抗菌株的筛选鉴定及促生防病特性分析

腐皮镰刀菌（Fusariumsolani）是可以引起茶树茎腐和枯萎的致病真菌。为获得对茶树腐皮镰刀菌有拮抗效果的生防菌株，从河南省信阳市新县茶园收集的茶树（Camelliasinensis）健康叶片中采用梯度稀释法分离纯化得到内生细菌56株，通过平板对峙法筛选对腐皮镰刀菌抑制效果较好的菌株，并根据形态特征、生理生化特征和分子生物学技术对其进行鉴定，测定其防病促生指标并进行抑菌谱试验，通过发酵液试验和平板对扣法评估挥发性物质对腐皮镰刀菌菌丝生长的影响。结果显示，筛选得到的菌株YB-1476对腐皮镰刀菌菌丝生长抑制率达到63.31%，拮抗效果最佳，鉴定其为贝莱斯芽孢杆菌（Bacillus velezensis）。该菌株有产铁载体和吲哚乙酸、分泌β-1,3-葡聚糖酶和纤维素酶及溶磷的能力。抑菌谱试验表明，菌株YB-1476对平脐蠕孢菌（Bipolarissorokinana）、禾谷镰刀菌（FusariumgraminearumPH-1）、念珠状镰刀菌（Fusarium moniliforme）、尖孢镰刀菌（Fusariumoxysporumf.sp.niveum）和茄链格孢菌（Alterna...     

生防 细菌 PP19 和 SI17 菌悬液对 荔枝霜疫病的防病作用初探

【目的】筛选新型高效的生防有益细菌防治果树病害如采后荔枝霜疫病,减少在运输过程中的损失,延缓褐变;揭示生防菌发挥防病作用的可能机制。【方法】将前期优选的生防解淀粉芽孢杆菌(Bacillus amyloliquefaciens)PP19和生防乙酰微小杆菌(Exiguobacterium acetylicum)SI17,分别制备其菌体悬浮液,喷雾预处理采后荔枝果实,24 h后喷雾接种霜疫霉菌(Peronophythora litchii)SC18,随后观察果实病害严重度,检测不同时间点果皮对应的酶活性或物质含量。【结果】生防菌PP19和SI17菌悬液均显著降低采后荔枝霜疫病的发生,防效分别达到39.59%~88.76%和18.08%~91.01%;菌悬液提高果皮CAT、SOD、GLU、PAL、PPO活性,增加果皮花色素苷含量;同时,降低果皮花色素苷酶活性、H_2O_2含量及总酚含量。SI17比PP19更能提高植物几丁质酶活性。【结论】通过上述结果,推测两个生防菌发挥生防效果可能与改变了果皮抗病相关酶活性或物质含量有关。     

根际促生菌的生防机理及用作生防制剂的潜能

植物根际促生菌是一类可以显著提高植物生活力或植物抗病害能力的天然土壤细菌,除可经由多种途径促进植物的营养吸收与物质积累、提高植物的各项生长参数与生理生化指标外,其还可通过多种途径对植物病害加以防治。根际促生菌的生物防治活性依赖于其在植物根际的定殖,并经由特定生防活性物质的分泌、对植物系统抗性的诱导来加以实现。利用根际促生菌在植物根际的定殖,可对植物病害病原菌的生长造成抑制,这对于一些难以使用化学药剂进行防治的植物病害十分关键。本文论述了根际促生菌的生物防治机理,并探讨了将根际促生菌用作植物病害的生物防治剂的可能性,可为生态农业的发展提供了新思路。     

解淀粉芽胞杆菌YB114对黄瓜棒孢叶斑病的生防效果及发酵条件优化

解淀粉芽胞杆菌YB114为本研究团队筛选出的一株对黄瓜棒孢叶斑病(Corynespora leaf spot)具有较高活性的生防菌株。为加快其产业化进程，本试验研究了该菌株的生物活性及发酵条件。盆栽试验结果表明，100倍发酵稀释液处理对黄瓜棒孢叶斑病的治疗及预防效果分别为85.72%和42.29%,100倍发酵上清稀释液的治疗及预防效果分别达到74.14%和33.25%,菌株发酵液和上清液对黄瓜棒孢叶斑病的治疗效果好于预防效果。YB114发酵液对黄瓜植株有促生效果，叶面喷施后黄瓜茎长、根长、叶面积及地上部生物量增加，叶片中叶绿素、生长素和玉米核苷素含量显著增加。发酵最优培养基为10 g/L果糖、17 g/L水溶性花生饼粉、1 g/L磷酸二氢钾。最佳发酵条件为：装液量40 mL/250 mL三角瓶，接种量6%(体积分数)、pH 7.0,转速180 r/min,温度32℃,发酵时间24 h。优化发酵条件后YB114对棒孢叶斑病的防效提升了22.4%。     

A review of biocontrol agents in controlling late blight of potatoes and tomatoes caused by Phytophthora infestans and the underlying mechanisms

Phytophthora infestans causes late blight on potatoes and tomatoes, which has a significant economic impact on agriculture. The management of late blight has been largely dependent on the application of synthetic fungicides, which is not an ultimate solution for sustainable agriculture and environmental safety. Biocontrol strategies are expected to be alternative methods to the conventional chemicals in controlling plant diseases in the integrated pest management (IPM) programs. Well-studied biocontrol agents against Phytophthora infestans include fungi, oomycetes, bacteria, and compounds produced by these antagonists, in addition to certain bioactive metabolites produced by plants. Laboratory and glasshouse experiments suggest a potential for using biocontrol in practical late blight disease management. However, the transition of biocontrol to field applications is problematic for the moment, due to low and variable efficacies. In this review, we provide a comprehensive summary on these biocontrol strategies and the underlying corresponding mechanisms. To give a more intuitive understanding of the promising biocontrol agents against Phytophthora infestans in agricultural systems, we discuss the utilizations, modes of action and future potentials of these antagonists based on their taxonomic classifications. To achieve a goal of best possible results produced by biocontrol agents, it is suggested to work on field trials, strain modifications, formulations, regulations, and optimizations of application. Combined biocontrol agents having different modes of action or biological adaptation traits may be used to strengthen the biocontrol efficacy. More importantly, biological control agents should be applied in the coordination of other existing and forthcoming methods in the IPM programs. © 2023 Society of Chemical Industry.