Characterization,phylogenetic analyses and pathogenicity of Bipolaris setariae associated with brown stripe disease on sugarcane in Yunnan,China

Brown stripe disease is a severe foliar fungal disease of sugarcane worldwide and is widespread in all sugarcane planting areas in China. Brown stripe is a major disease that seriously affects the output and quality of the sugarcane industry in Yunnan Province, China's second-largest sugar base, while the pathogen of this disease remains not yet fully understood. To address this, we isolated and identified the fungi associated with 68 leaf samples showing typical symptoms of brown stripe from 22 sugarcane varieties in different areas of Yunnan Province. A total of 113 isolates were obtained, which were morphologically similar. Of these, 64 representative isolates were sequenced for the internal transcribed spacer region (ITS), GAPDH and EF-1α loci. All representative isolates grouped with the type strain of Bipolaris setariae in the phylogenetic trees inferred with individual and concatenated sequences of ITS, GAPDH and EF1-α. Pathogenicity test results showed that B. setariae strains were able to induce typical symptoms of brown stripe. The results obtained in this study clarify that only B. setariae is associated with sugarcane brown stripe in Yunnan, China. It is recorded here for the first time as a pathogen causing sugarcane brown stripe in Yunnan, and it is able to infect many major cultivars and new varieties, posing a new threat to the sugar industry in Yunnan Province. In addition, these results provide the scientific basis for the future breeding of disease-resistant varieties and effective prevention and control of sugarcane brown stripe disease.     

二化螟dsRNA降解酶基因的克隆与表达分析

为解析二化螟Chilo suppressalis体内参与降解双链RNA(double-stranded RNA,dsRNA)的关键核酸酶的功能,克隆二化螟不同的非专一性核酸酶（non-specific nuclease,NUC）基因,并对这些基因进行生物信息学分析和组织定量表达分析,同时对dsRNA降解酶（dsRNA degrading nuclease,dsRNase）活力的组织分布进行研究。结果显示,共克隆获得5个NUC基因,其中有4个编码dsRNase亚家族基因（CsdsRNase1～CsdsRNase4）和1个编码Endonuclease G亚家族基因（CsEndoG）。5个NUC基因的开放阅读框核苷酸序列长度范围为828～1 338 bp,编码275～445个氨基酸残基,其分子量大小为31.68～49.57 kD,预测等电点为5.48～9.42。CsdsRNase1和CsdsRNase2含有信号肽序列,两者相似度极高,且与家蚕Bombyx mori和斜纹夜蛾Spodoptera litura中具有dsRNA降解酶活力的dsRNase同源聚类;CsdsRNase1和CsdsRN...     

光源、性别及光处理时间对草地贪夜蛾趋光行为的影响

为研发高效、精准的监测防控设备,利用八臂行为选择装置系统测定不同光源、性别和光处理时间下草地贪夜蛾Spodoptera frugiperda的趋光行为。结果显示,在紫外光（波长365 nm）、紫光（波长420～430 nm）、蓝光（波长465～475 nm）、绿光（波长525～535 nm）、黄光（波长585～595 nm）和红光（波长655～665 nm）6种波长光源下,草地贪夜蛾混合种群（雌雄成虫比为1∶1）对紫外光光源的趋光选择率最高,为25.61%,显著高于其他处理,其次为紫光和蓝光光源,趋光选择率分别为16.30%和8.82%,对红光的趋光选择率最低,为4.76%。在紫外光刺激下,草地贪夜蛾雌成虫的趋光选择率显著高于混合种群（雌雄成虫比为1∶1）,在红光刺激下,雄成虫的趋光选择率显著高于雌成虫。另外,在紫外光刺激下,光处理时间60 min草地贪夜蛾雌成虫的趋光选择率显著高于其他处理。表明光源与性别因素均影响草地贪夜蛾的趋光行为,光处理时间对草地贪夜蛾的趋光行为影响较小,且与光源及性别因素有关。     

广东省稻菜轮作区中牛筋草对十种除草剂的抗性水平及靶基因序列分析

为明确广东省稻菜轮作区中牛筋草对10种常用除草剂的抗性水平及抗性分子机制,采用整株生物测定法测定广东省稻菜轮作区内8个牛筋草种群P1～P8对草甘膦、草铵膦和乙酰辅酶A羧化酶(acetyl-CoA carboxylase,ACCase)抑制剂类等10种除草剂的抗性水平,并进一步分析P1和P8种群相关靶标酶基因5-烯醇丙酮酰莽草酸-3-磷酸合酶(5-enolpyruvyl-shikimate-3-phosphate synthase,EPSPS)、谷氨酰胺合成酶(glutamine synthetase,GS)和ACCase的部分功能区序列特征。结果显示,牛筋草P1～P8种群对草甘膦抗性指数为敏感种群的5.9倍～17.7倍,其中P8种群对草甘膦的抗性水平最高;8个种群对草铵膦也产生了不同程度的抗性,抗性指数为敏感种群的2.3倍～14.2倍,其中P1种群抗性最高。牛筋草P1和P8种群均对ACCase抑制剂类除草剂精喹禾灵、氰氟草酯和噁唑酰草胺产生了交互抗性;P1种群ACCase基因在第2 041位氨基酸处发生突变,该突变在牛筋草种群中首次发现;而P8种群ACCase基因则在第2 027位氨基...     

四种替代药剂对梨火疫病菌的抑制活性及其田间防效

为筛选农用链霉素替代药剂,以其为对照药剂,测定春雷霉素、中生菌素、噻霉酮和噻菌铜这4种常用细菌病害防治药剂对梨火疫病菌Erwinia amylovora的抑制活性、对梨火疫病的田间防效及不同药剂处理后梨中的农药残留,并对这4种药剂的作物安全性进行评价。结果表明,中生菌素、噻霉酮和春雷霉素对梨火疫病菌有抑制作用,抑制中浓度EC50分别为1.60、6.64和60.57 mg/L,中生菌素的抑制效果高于链霉素。在连续2年田间试验中,中生菌素1 000倍液和春雷霉素400倍液对梨火疫病的保护效果和治疗效果均达90.33%以上,噻霉酮500倍液和噻菌铜200倍液对梨火疫病的保护效果均达100.00%,治疗效果均超过86.97%,与对照药剂农用链霉素2 000倍液的效果相当。所有药剂处理后均未检出中生菌素、春雷霉素、高效氯氰菊酯和农用链霉素的农药残留,而噻虫嗪、阿维菌素和矮壮素虽有检出,但其残留量均低于国家限量标准。花期前后、幼果期和果实膨大期施药,中生菌素、春雷霉素、噻霉酮和噻菌铜对梨花、叶片、枝梢及果实生长均无不良影响。综合来看,中生菌素、春雷霉素、噻霉酮和噻菌铜均可作为农用链霉素的替代药剂,...     

Application and mechanisms of metal-based nanoparticles in the control of bacterial and fungal crop diseases

Nanotechnology is a young branch of the discipline generated by nanomaterials. Its development has greatly contributed to technological progress and product innovation in the field of agriculture. The antimicrobial properties of nanoparticles (NPs) can be used to develop nanopesticides for plant protection. Plant diseases caused by bacterial and fungal infestations are the main types of crop diseases. Once infected, they will seriously threaten crop growth, reduce yield and quality, and affect food safety, posing a health risk to humans. We reviewed the application of metal-based nanoparticles in inhibiting plant pathogenic bacteria and fungi, and discuss the antibacterial mechanisms of metal-based nanoparticles from two aspects: the direct interaction between nanoparticles and pathogens, and the indirect effects of inducing plant resilience to disease. © 2022 Society of Chemical Industry.