Detection of streptomycin resistance in Erwinia amylovora strains isolated from apple orchards in Chihuahua, Mexico     

Adrian Ponce de León Door  Alejandro Romo Chacón  Carlos Acosta Muñiz. 《European journal of plant pathology / European Foundation for Plant Pathology》2013,137(2):223-229

Fire blight, one of the most severe diseases of apple and pear, is caused by the bacterium Erwinia amylovora. One control method is the use of antibiotics like streptomycin; however, streptomycin is the only antibiotic registered to control fire blight. A total of 107 E. amylovora strains were isolated from apple orchards located in Cuauhtémoc and Guerrero, Chihuahua, two major apple-producing areas in Mexico, showing 40 and 24 % streptomycin-resistant strains, respectively. The identification of E. amylovora strains was performed by polymerase chain reaction (PCR) amplification of a 900-bp region located within the non-transferable pEA29 plasmid and by amplification of a specific 1,269-bp region located on the E. amylovora chromosome. The 107 isolates tested carried the pEA29 plasmid, and 36 % of the isolates from both locations showed high resistance to streptomycin at levels that ranged from 200 to ≥1,000 μg ml^?1 streptomycin. The strA-strB and aadA genes, which encode enzymes that inactivate streptomycin, and a mutation in codon 43 of the rpsL gene that confers high resistance to the antibiotic were examined to determine the mechanism of streptomycin resistance. In total, 95 % of the resistant strains showed a single base pair mutation in codon 43 of the rpsL gene, causing an amino acid substitution in ribosomal protein S12. The presence of strA-strB and aadA genes or the rpsL mutation was not identified in the other 5 % of resistant strains, suggesting the existence of a new streptomycin resistance mechanism in E. amylovora.  相似文献   

Highly infested soils undermine the use of resistant olive rootstocks as a control method of verticillium wilt     

Pedro Valverde  Carlos Trapero  Octavio Arquero  Nicolás Serrano  Diego Barranco  Concepción Muñoz Díez  Francisco J. López-Escudero 《Plant pathology》2021,70(1):144-153

Verticillium wilt of olive (VWO) is probably the most devastating fungal disease for olive trees worldwide, and currently the main cultivars are susceptible or moderately susceptible to this disease. The evaluation of resistant cultivars as rootstocks to control the disease has scarcely been explored, and mainly in short-term studies under controlled conditions, which usually do not correspond with field evaluations. The main objective of this study was to assess the responses to VWO of different scion × rootstock combinations of the olive cultivars Picual, Arbequina, Changlot Real, and Frantoio in a long-term field experiment with a soil highly infested with the defoliating pathotype of Verticillium dahliae. The results showed that grafting the susceptible cultivar Picual onto resistant rootstocks delayed the onset of the disease symptoms; however, after 4 years, it was observed that all combinations that contain Picual (a) were extensively colonized by V. dahliae; (b) developed severe symptoms of the disease; and (c) had plant mortality similar to Picual growing on its own roots. This result highlights the importance of long-term field experiments to evaluate VWO and shows that grafting susceptible olive cultivars onto resistant ones does not provide a durable control of VWO under high inoculum potential, as V. dahliae is able to progress through the resistant rootstock and then extensively colonize and kill the susceptible scion. However, the high inoculum potential observed in this study does not allow us to consider the evaluated resistant cultivars as completely ineffective under lower inoculum densities.  相似文献   

2012—2016年《中国渔业质量与标准》高被引论文特征分析     

刘露  徐锦华  穆迎春  韩刚  郑重  许玉艳 《中国渔业质量与标准》2022,(1):65-69

利用CNKI中国引文数据库,以2012—2016年发表于《中国渔业质量与标准》高被引论文为基础数据,并以《我国大宗淡水鱼产业发展现状与体系研究进展》为例分析了综述类高被引主要特征.结果表明:高被引论文首次引用大多在发表1～2年后,被引高峰在发表4～6年后,但检测类文章较该时间会提前1～2年;高被引论文与期刊高频关键词具...  相似文献   

化学疏花对欧李果实产量和品质的影响   总被引：2，自引：0，他引：2  

王鹏飞  张建成  曹琴  穆霄鹏  纪薇  杜俊杰 《山东农业科学》2014,(2):56-58

试验以6年生‘农大4号’欧李为试材,于盛花期分别喷施不同浓度的3种疏花剂,测定植株坐果率、成熟期果实产量及糖酸含量。结果表明:喷施1.0 Be°石硫合剂可显著提高平均单果重和可溶性固形物含量,平均单枝果重和可滴定酸含量也有提高。喷施20 mg/L萘乙酸或10.0 g/L的施易乐效果较好。建议在欧李盛花期喷施1.0 Be°石硫合剂进行疏花。  相似文献   

Influence of carbonization temperature on the anatomical characteristics of Ocotea porosa (Nees & Mart. Ex Nees) L. Barroso     

Silvana Nisgoski  Graciela Inés Bolzon de Muñiz  Francielli Rodrigues Ribeiro Batista  Richard Eduard Mölleken 《Wood Science and Technology》2014,48(2):301-309

The carbonization process causes different physical and chemical transformations to wood, affecting the final properties of the charcoal produced. In Brazil, the cutting and use of Ocotea porosa (Nees & Mart. Ex Nees) L. Barroso is legally prohibited. But the difficulty of identifying the species used to produce charcoal hinders enforcement efforts to protect this and other endangered tree species. The aim of this work was to characterize the anatomy of charcoal made from O. porosa at different temperatures to provide information to facilitate differentiation of the species by the authorities in charge of suppressing illegal commerce. Samples were carbonized by direct heating and final temperatures of 350, 450 and 650 °C, besides a group under a ramp heating regime also with a final temperature of 450 °C. The qualitative characteristics of the O. porosa wood were preserved at the carbonization temperatures studied permitting the use of its anatomical structures for identification of carbonized wood to support control of the illegal trade in charcoal of this species.  相似文献   

基于叶片图像特征数字化信息识别7种柳属植物1）   总被引：1，自引：0，他引：1  

杨天天  潘晓星  穆立蔷 《东北林业大学学报》2014,(12)

通过对7种柳属植物的350枚叶片进行实验处理,测量所需的数字化植物特征,在单一指标判别分析中,仅有“长宽比”作为识别这7种植物的最有效的单一指标;在双重指标的判别分析中,“最宽处”ד叶脉值”、“最宽处”ד短弧距”、“最宽处”ד长弧距”、“周长比”ד膜周长比”、“短弧距”ד上外距”、“长弧距”ד上外距”这6组双重指标对7种植物的识别正确率均达到100％,同为最优双重指标。试验结果表明,上述6组最优双重指标可以完全识别出这7种植物。因此,基于数字化的叶片图像特征的信息识别物种是可行的,为今后植物物种识别研究奠定了基础。  相似文献   

云南省丽江玉龙县蜜源植物资源初步调查     

周丽贞  杨金兰  木积成 《中国蜂业》2014,(13):26-32

通过初步调查,丽江玉龙县有蜜源植物171种,分属于54科,128属。蜜源植物资源丰富,种类多样,全年皆有花开。蜜源开花期主要集中在冬末至春季、夏末至冬初,适合发展养蜂业。有毒蜜源植物有4种,分别为紫花醉鱼草、瑞香狼毒、蓖麻、白花曼陀罗。  相似文献   

任务驱动教学法在高职photoshop教学中的应用研究     

穆雪 《辽宁农业职业技术学院学报》2014,(3):47-49

高等职业院校主要是根据市场的需求,培养各种应用型的专业人才。Photoshop课程是高等院校平面设计专业的核心课程之一,该课程在整个课程体系中具有十分重要的地位。因此该课程的教学对学生的发展也具有举足轻重的作用。然而,在高职学院有关此课程的教学过程还存在着一些问题。任务驱动教学法能够激发学生的学习兴趣,提高学习效率。把任务驱动教学法应用于具体的高职Photoshop课程中,进一步验证了任务驱动教学法在photoshop课程教学中的积极作用。  相似文献   

艾比湖流域年径流变化特征分析   总被引：4，自引：0，他引：4  

乔木  周生斌  卢磊 《水土保持学报》2010,24(6)

以艾比湖流域的博尔塔拉河(博河)和精河为例,基于1961-2008年的径流序列,运用累计距平法、小波分析法和滑动t检验等方法,分析了艾比湖流域年径流变化的趋势特征、周期特征和突变特征,揭示了流域径流的变化规律,得出以下结论:(1)从长时间尺度上来看,艾比湖流域博河和精河两条河流的年径流量均呈增加的趋势;从短的时间尺度上来看,流域内两条河流的径流量又表现出一定的波动性。(2)艾比湖流域河流的年径流均存在明显的周期性。(3)在20～25年的时间尺度上,两条河流均经历了一个丰枯交替;在10～20年的周期尺度上,博河和精河径流量经历了多次丰枯交替;在10年以下的周期尺度上,两条河流的周期性都比较复杂。(4)博河和精河年径流量变化趋势比较显著,两条河流均在1998年发生了一次由少到多的转折突变。  相似文献   

养殖固体废弃物作碳源的海水养殖废水反硝化净化效果   总被引：8，自引：3，他引：5  

李秀辰  李俐俐  张国琛  牟晨晓  母刚 《农业工程学报》2010,26(4):275-279

由于养殖废水C/N低且溶解氧（DO）含量高,需要补充碳源并有效脱氧,才能保证高效反硝化。该文开展了以养殖固体废弃物作碳源,海水养殖废水水解、反硝化净化工艺的试验研究。结果表明,养殖废水（水解种污泥与养殖固体废弃物体积比为1︰1、水温20℃）经过10 h水解,水解液DO质量浓度降至0.2 mg/L,NH4+-N、NO3--N、总有机物（TCOD）和总固体（TS）的去除率分别为62.8%、43.5%、24.0%和13.6%。当水解种污泥与养殖固体废弃物体积比为1︰1.5～1︰2.5时,养殖废水在20℃条件下水解6 h,水解液中挥发性脂肪酸（VFA）质量浓度和溶解性有机物/总有机物（SCOD/TCOD） 分别增加32.0%～49.3%和3.5%～9.1%。利用厌氧活性污泥对养殖废水的水解液（体积比为1︰4、水温20℃）进行反硝化净化,NO3--N和TCOD的3 h去除率分别达99.6%和88.3%,而养殖废水直接反硝化10 h, NO3--N和TCOD的去除速率分别为36.5%和75.9%。这表明,在海水循环水养殖系统中,利用养殖固体废弃物作碳源,养殖废水水解、反硝化工艺,能有效脱氧和补充有机碳源,养殖废水反硝化净化效果显著。  相似文献