番茄产后灰霉病的病原鉴定及生物防治

为探索生物防治番茄产后灰霉病,采用柯赫氏法则从罹病的番茄果实上分离得到菌株FQ-2,基于形态学和rDNA-ITS序列,对该菌株进行病原鉴定,采用小麦内生菌解淀粉芽孢杆菌B9601-Y2(Y2)和球花石斛内生菌贝莱斯芽孢杆菌DJB5(DJB5)对番茄灰霉病进行生物防治。FQ-2被鉴定为灰葡萄孢菌(Botrytis cinerea),且Y2和DJB5对番茄产后果实灰霉病均有较好的预防和治疗效果,Y21×10^(7) cfu/mL和DJB51×10^(8) cfu/mL悬浮剂在处理当天接种FQ-2,10天后的防效分别达88.10%和73.47%。在接种灰霉病菌当天再接种1×10^(8) cfu/mL的Y2和1×10^(7) cfu/mL的DJB5,10天后灰霉病的防治效果分别达68.56%和78.74%。研究结果对番茄产后灰霉病的生物防治具有参考作用。

香蕉内生贝莱斯芽孢杆菌YX-11的分离鉴定与功能研究

为了找到安全有效的防控香蕉枯萎病的生防菌株,采用组织分离法从香蕉叶片中分离出内生细菌菌株YX-11。采用形态学、生物化学和16S rDNA基因序列分析,该菌株被鉴定为贝莱斯芽孢杆菌Bacillus velezensis。YX-11具有溶磷、解钾和固氮的能力,还可以促进香蕉的生长,能抑制10种植物病原菌,其中对香蕉枯萎病菌、烟草疫霉病菌和烟草赤星病菌的抑制率分别达71.30%、72.77%和72.19%。它的带菌苗结合生物有机肥施用,以及多次喷施对田间香蕉枯萎病的防治效果达75.56%。

表面活性素促进枯草芽胞杆菌XF-1在大白菜叶际定殖能力研究

枯草芽胞杆菌XF-1是一株大白菜内生生防菌,通过叶面喷施的方式可有效防控大白菜根肿病,但其叶际定殖的分子机制尚不明确。为了明确表面活性素对XF-1在大白菜叶际定殖的影响,进一步提高其在田间应用效果,本研究通过测定生长曲线、泳动运动、群集运动和24孔细胞培养板静置培养试验,分析表面活性素对XF-1菌株生长速率、运动能力和生物膜形成水平的影响;利用叶片-微生物互作分析和定殖试验,测定XF-1及突变体XF-1-ΔsrfA在大白菜叶表黏附和植株内的定殖能力。结果表明,XF-1-ΔsrfA与XF-1相比生长曲线没有明显差异,泳动能力和群集运动能力分别显著下降了36.8%和43.9%,静置培养24 h后生物膜形成能力显著下降53.9%,48 h后无显著差异。叶片-微生物互作试验中,突变体标记菌XF-1-ΔsrfA-gfp黏附效率较XF-1-gfp约下降80%。喷施接种3~7 d后,XF-1-ΔsrfA-gfp相较于XF-1-gfp在大白菜叶片内和根系中的定殖数量均显著下降。试验结果表明表面活性素对枯草芽胞杆菌XF-1在大白菜叶际定殖具有较为明显的促进作用,srfA基因的缺失显著抑制XF-1的叶际定殖能力。

10种农业化学品对柑橘内生菌枯草芽孢杆菌L1-21的影响

【目的】明确农业化学品对柑橘内生菌的影响,指导柑橘合理用药。【方法】采用平板菌落计数法,测定了6种杀虫剂、3种杀菌剂和微肥EDTA-Cu对生防菌株枯草芽孢杆菌L1-21的相容性及对柑橘植株内生菌的抑制作用。【结果】56.00 mg·L^(-1)吡虫啉、121.80 mg·L^(-1)虫螨腈、4.00 mg·L^(-1)甲氨基阿维菌素、50.00 mg·L^(-1)噻虫嗪、45.60 mg·L^(-1)氟氯氰菊酯、800.00 mg·L^(-1)辛硫磷、402.00 mg·L^(-1)喹啉铜、3728.00 mg·L^(-1)硫磺、620.60 mg·L^(-1)氧化亚铜和321.00 mg·L^(-1)EDTA-Cu在平板上对L1-21的抑制率均达100.00%。2倍剂量处理离体叶片24 h后,除8.00 mg·L^(-1)甲氨基阿维菌素的抑制率(16.84%)显著低于其他5种杀虫剂外,其他5种杀虫剂对L1-21的抑制率均无显著差异。2倍剂量处理柑橘活体叶片24 h后,8.00 mg·L^(-1)甲氨基阿维菌素对柑橘叶片内的L1-21抑制作用(4.23%)不明显,显著低于其他5种杀虫剂和3种杀菌剂与微肥EDTACu;对内生菌总量的抑制率以8.00 mg·L^(-1)甲氨基阿维菌素(6.78%)最低,其他制品达46.90%~70.06%,且差异未达显著水平。【结论】10种农业化学品在平板上均可抑制L1-21,抑制率的大小与其浓度有关。2倍田间登记使用量处理时,10种农业化学品均可影响L1-21在柑橘叶片上的定殖及降低柑橘内生细菌总量。因此,田间施用化学品对柑橘内生菌的负面影响不可忽视。

山东玉米白斑病鉴定及我国白斑病发生流行风险分析

为评估玉米白斑病在我国发生流行的风险,对疑似白斑病病样进行分离,采用抗病性鉴定以及气象数据对白斑病病原菌流行进行评估,经形态学特征观察和分子鉴定确定山东滕州玉米白斑病病原菌的分类地位。结果表明,引致山东滕州玉米白斑病的病原菌ST-1与云南白斑病病原菌WS-191同为宽胫附球孢(Epicoccum latusicol⁃lum)。两个菌株最适生长温度均为25~28℃,pH值为5~7。气象数据分析表明,我国8个玉米主产区4-9月平均温度为10~30℃,适合白斑病发生流行。在645个西南玉米区试新品种抗病性鉴定中,中抗-高抗377个,占58.44%;感病-高感品种268个,占41.56%。综上所述,我国主要玉米产区均有白斑病发生条件,存在大面积流行的风险。

Crop diversity and pest management in sustainable agriculture

Large-scale crop monocultures facilitate the proliferation and increasing prevalence of diseases and pest insects.Many studies highlight the impacts of plant diversification upon pathogens,and the population dynamics of insects and beneficial organism in agricultural ecosystems.These studies provide evidence that habitat manipulation techniques such as intercropping,relay,and rotation can significantly improve disease and pest management.This review introduces the concept of crop diversity,considers recent insights and mechanisms underlying crop diversity,and discusses its potential for improving sustainable agricultural practices.Recently,the phytobiomes resulting from increased crop diversity are increasingly recognized for their contribution to disease and pest control.Further,understanding the interactions between pathogens or pests with their host phytobiome may lead to novel options for the prevention of pests.Recent advances in the agricultural systems include:(i)a better understanding of the mechanisms of interactions between crop species and genotypes;(ii)ecological progress including a better understanding of the context-dependency of those interactions;and(iii)the role of microtopographic variation in agricultural systems for priming basal resistance to multiple pests and pathogens by intercropped crops.We also highlight recent progress in China and the potential options for habitat management and design that enhance the ecological role of biodiversity in agroecosystems.

First report on molecular characterization of Leishmania species from cutaneous leishmaniasis patients in southern Khyber Pakhtunkhwa province of Pakistan

Objective: To report presence of Leishmania major in Khyber Pakhtunkhwa of Pakistan, where cutaneous leishmaniasis(CL) is endemic and was thought to be caused by Leishmania tropica only. Methods: Biopsy samples from 432 CL suspected patients were collected from 3 southern districts of Khyber Pakhtunkhwa during years 2011–2016. Microscopy on Giemsa stained slides were done followed by amplification of the ribosomal internal transcribed spacer 1 gene. Results: Leishmania amastigotes were detected by microscopy in 308 of 432 samples(71.3%) while 374 out of 432 samples(86.6%) were positive by ribosomal internal transcribed spacer 1 PCR. Subsequent restriction fragment length polymorphism confirmed Leishmania tropica in 351 and Leishmania major in 6 biopsy samples. Conclusions: This study is the first molecular characterization of Leishmania species in southern Khyber Pakhtunkhwa. It confirmed the previous assumptions that anthroponotic CL is the major CL form present in Khyber Pakhtunkhwa province. Furthermore, this is the first report of Leishmania major from a classical anthroponotic CL endemic focus identified in rural areas of Kohat district in southern Khyber Pakhtunkhwa.

Molecular detection of Leishmania species in human and animals from cutaneous leishmaniasis endemic areas of Waziristan, Khyber Pakhtunkhwa, Pakistan

Objectives: To detect Leishmania species in human patients, animal reservoirs and Phlebotomus sandflies in Waziristan, Pakistan. Methods: Tissue smears and aspirates from 448 cutaneous leishmaniasis(CL) suspected patients were analyzed. To sort out role of the reservoir hosts, skin scrapings, spleen and liver samples from 104 rodents were collected. Furthermore, buffy coat samples were obtained from 60 domestic animals. Sandflies were also trapped. All human, animals and sandfly samples were tested by microscopy, kinetoplastic PCR and internal transcribed spacer 1(ITS1) PCR followed by restriction fragment length polymorphism for detection of Leishmania species. Results: An overall prevalence of 3.83% and 5.21% through microscopy and ITS1 PCR respectively was found. However, the statistically non-significant correlation was found between area, gender, and number of lesions. The presence of rodents, sandflies, domestic animals and internally displaced people increased the risk of CL. Using ITS1-PCR-RFLP, Leishmania tropica(L. tropica) was confirmed in 106 samples while 25 of the isolates were diagnosed as Leishmania major(L. major). Similarly, 3/104 rodents were positive for L. major and 14 pools of DNA samples containing Phlebotomus sergenti sandflies were positive for L. tropica. None of samples from domestic animals were positive for leishmaniasis. Conclusions: In the present study, L. tropica and L. major are found to be the main causative agents of CL in study area. Movement of internally displaced people from CL endemic areas presents a risk for nearby CL free areas. To the best of our knowledge, we report for the first time L. major infection in rodents(Rattus rattus) and L. tropica in Phlebotomus sergenti sandflies trapped in Waziristan, Pakistan.

高山杜鹃褐斑病病原学研究

为明确引起高山杜鹃褐斑病的病原菌及其生物学特性,采用形态学及分子生物学方法对病原菌进行了鉴定,并采用平板培养法研究了该病菌的生物学特性,筛选了化学杀菌剂及生防细菌。形态特征及rDNA-ITS序列、β-tubulin基因和tef1基因序列分析结果表明,引起高山杜鹃褐斑病的病原菌为棒孢新拟盘多毛孢Neopestalotiopsis clavispora;该病原菌最适生长温度为25–28℃,适宜在偏酸性培养基上生长,最适碳、氮源分别为葡萄糖和牛肉膏,最适生长培养基为PDA。毒力测定结果表明,苯醚甲环唑、氟硅唑、氟环唑、戊唑醇及异菌脲对棒孢新拟盘多毛孢的EC50分别为0.7991、2.2756、2.7425、3.7366和4.8757 mg/L;实验室前期筛选出芽胞杆菌属的4株生防细菌,在室内处理离体叶10 d后,对褐斑病的防效达57.51%–75.97%。为研究高山杜鹃褐斑病的防控提供了科学依据。