Low root‐to‐root transmission of a tobamovirus,yellow tailflower mild mottle virus,and resilience of its virions          下载免费PDF全文

S. H. Koh  H. Li  K. Sivasithamparam  R. Admiraal  M. G. K. Jones  S. J. Wylie 《Plant pathology》2018,67(3):651-659

Tobamoviruses are serious pathogens because they have extremely stable virions, they are transmitted by contact, and they often induce severe disease in crops. Knowledge of the routes of transmission and resilience of tobamovirus virions is essential in understanding the epidemiology of this group of viruses. Here, an isolate of the tobamovirus yellow tailflower mild mottle virus (YTMMV) was used to examine root‐to‐root transmission in soil and in a hydroponic growth environment. Root‐to‐root transmission occurred rarely, and when it occurred plants did not exhibit systemic movement of the virus from the roots to the shoots over a 30‐day period. The resilience of YTMMV virions was tested in dried leaf tissue over time periods from one hour to one year under temperatures ranging from ?80 to 160 °C. Infectivity was maintained for at least a year when incubated at ?80 or 22 °C, or at fluctuating ambient temperatures of 0.8 to 44.4 °C, but incubation under dry conditions at 160 °C for >4 days eliminated infectivity. Exposure of virions to 0.1 m sodium hydroxide or 20% w/v skimmed milk solution for 30 min, treatments recommended for tobamovirus inactivation, did not abolish infectivity of YTMMV.  相似文献   

Pythium yorkensis sp. nov., a potential soybean pathogen from southeastern Pennsylvania,USA          下载免费PDF全文

S. T. Veterano  L. S. Coffua  J. I. Mena‐Ali  J. E. Blair 《Plant pathology》2018,67(3):619-625

Biodiversity surveys of natural as well as agricultural ecosystems commonly reveal novel isolates. A new species, Pythium yorkensis sp. nov., is reported here, isolated from field soil during a survey of oomycete diversity in symptomless soybean across southeastern Pennsylvania. Molecular data from both mitochondrial and nuclear loci support a unique phylogenetic position for the isolates collected, and morphological features distinguish this new species from close relatives in Pythium clade J. Pathogenicity assays suggest that this new species may be a potential agricultural pathogen, as isolates were mildly aggressive on soybean. This study highlights the continued need for culture‐based surveys in collaboration with high‐throughput sequence‐based approaches for environmental sampling.  相似文献   

Phylogenetic position and nucleotide diversity of Fusarium oxysporum f. sp. vanillae worldwide based on translation elongation factor 1α sequences          下载免费PDF全文

F. R. Flores‐de la Rosa  E. De Luna  J. Adame‐García  L. G. Iglesias‐Andreu  M. Luna‐Rodríguez 《Plant pathology》2018,67(6):1278-1285

Fusarium oxysporum f. sp. vanillae is considered the most important fungus affecting vanilla crops around the world, causing rot on vanilla roots and stems. Previous studies showed that the ability to infect vanilla plants is a polyphyletic trait among strains of the Fusarium oxysporum species complex (FOSC). The same studies proposed a single origin for F. oxysporum f. sp. vanillae isolates sampled from Mexico, the centre of origin and distribution of vanilla. The aim of this work was to test the hypothesis of the monophyletic origin of a wider sample of isolates of F. oxysporum f. sp. vanillae infecting Mexican vanilla and estimate nucleotide diversity of pathogen isolates from the main vanilla‐producing countries. Sequence data for the TEF1α gene from 106 isolates was assembled. The phylogenetic analyses suggest that some Mexican isolates of F. oxysporum f. sp. vanillae belong in two well‐supported clades, mixed with isolates from Madagascar, Indonesia, Réunion and Comoros. The phylogenetic position of other Indonesian and Mexican isolates is unresolved. Estimations of nucleotide diversity showed that the population from Mexico is genetically more diverse than the other three populations from Madagascar, Indonesia and Réunion. The results support a polyphyletic origin of vanilla‐infecting isolates of F. oxysporum worldwide, and also reject the proposition that Mexican isolates have a single origin. The phylogenetic optimizations over the strict consensus tree of the ability to infect vanilla plants suggest that pathogenic strains around the world are the product of multiple shifts of pathogenesis and dispersion events.  相似文献   

Critical factors driving aphanomyces damping‐off and root disease in clover revealed and explained using linear and generalized linear models and boosted regression trees          下载免费PDF全文

M. P. You  K. Rensing  M. Renton  M. J. Barbetti 《Plant pathology》2018,67(6):1374-1387

Subterranean clover (Trifolium subterraneum) is an important forage legume in Mediterranean regions worldwide. Aphanomyces damping‐off and root disease (Aphanomyces trifolii) poses significant threat to its persistence and productivity. Studies were conducted to define how environmental explanatory variables (temperature, soil type, moisture, nutrition) and variety influence disease severity and consequent forage productivity and persistence. Relationships were modelled using linear and generalized linear models and boosted regression trees. Linear modelling highlighted complex relationships between environmental variables and each dependent variable (emergence, tap and lateral root disease, dry shoot and root weight). All environmental variables produced significant interaction and/or main effects within each dependent variable. Boosted regression trees supported the complex nature of relationships in linear models, with temperature and either soil or variety most, and nutrition least, influential. Heat maps showed more disease for low temperatures. Least tap root disease was under high temperatures, while least lateral root disease was under medium or high temperatures, low moisture, and in sand‐based soil. These are the first studies using modelling approaches to reveal the complexities of how fluctuating soil temperature, moisture and nutrition conditions, and soil type and variety, determine aphanomyces damping‐off and root disease severity and resultant adverse impacts on forage legume productivity and persistence. Outcomes are widely applicable across soilborne oomycete pathogens of forage legumes. Studies highlighted how warming temperatures and drying climate associated with climate change should reduce future impact and importance of this and other soilborne oomycete diseases of forage legumes favoured by cold temperatures and wet and waterlogged conditions.  相似文献   

Germinate to exterminate: chemical stimulation of Spongospora subterranea resting spore germination and its potential to diminish soil inoculum          下载免费PDF全文

M. A. Balendres  T. J. Clark  R. S. Tegg  C. R. Wilson 《Plant pathology》2018,67(4):902-908

Hoagland's solution (HS), a defined nutrient supplement for plants, has been previously reported to stimulate zoospore release from resting spores of the potato pathogen Spongospora subterranea f. sp. subterranea. This study obtained direct empirical evidence for an increase in zoospore release with HS treatment, and identified Fe‐EDTA as the stimulant component of HS. Stimulation of resting spores by HS and Fe‐EDTA resulted in greater and earlier zoospore release compared to a distilled water control, and in the presence of a susceptible tomato host plant resulted in enhanced root infection. Given the labile nature of S. subterranea zoospores, it was postulated that stimulation of premature release of zoospores from the dormant resting spores in absence of susceptible hosts could reduce soil inoculum levels. In two glasshouse trials in the absence of host plants, both Fe‐EDTA and HS soil treatments reduced S. subterranea soil inoculum levels, providing proof of concept for the ‘germinate to exterminate’ approach to inoculum management.  相似文献   

中国南方竹区4种竹笋夜蛾的形态比较研究     

张琴  张守科  汪建波  张威  舒金平  吴鸿  王浩杰 《植物保护》2018,44(3):43-48

竹笋夜蛾是我国重要的一类竹子笋期害虫,种类多,形态相似,难以区分,为更为准确地识别主要竹笋夜蛾的种类,本研究通过野外取样和室内饲养,对竹笋基夜蛾Kumasia kumaso、竹笋禾夜蛾Oligia vulgaris、笋连秀夜蛾Apamea repetita conjuncta及竹笋秀夜蛾Apamea apameoides 4种竹笋夜蛾卵、幼虫趾钩、臀棘及成虫翅脉和生殖器形态进行了观察和比较。结果表明,竹笋基夜蛾在卵形态、幼虫体色和雌雄生殖器形态上与其他3种竹笋夜蛾形态差异明显,其余3种夜蛾幼虫体表背线和亚背线形态有差异,趾钩、臀棘、翅脉和雌、雄外生殖器形态差异不显著。本研究明确了我国南方竹区4种竹笋夜蛾的形态差异,为竹笋夜蛾的精准防控提供了参考。  相似文献   

福建柳杉毛虫的七种寄生蝇形态记述和生物学   总被引：2，自引：0，他引：2  

梁光红  林浩宇  卢赐鼎  韩小红  华银  黄信金  谢作贵  张飞萍  张春田 《植物保护》2018,44(6):177-184

柳杉毛虫是一种严重为害柳杉的食叶害虫,探明柳杉毛虫的寄生蝇种类,将为该虫优势天敌的筛选提供更多的选择。本研究从野外采集柳杉毛虫幼虫并带回室内饲养,出蛆化蛹,羽化获得不同种类的寄生蝇。对获得的寄生蝇进行分类、鉴定,并描述其系统分类地位、形态特征、地理分布及寄主。调查发现,柳杉毛虫的寄生蝇由多到少依次为蚕饰腹寄蝇Blepharipa zebina(Walker),瘦钩鬃麻蝇Sarcophaga(Sarcorohdendorfia)gracilior(Chen),黑角狭颊寄蝇Carcelia(s.str.)nigrantennata Chao et Liang,松毛虫狭颊寄蝇C.(s.str.)matsukarehae(Shima),星毛虫狭颊寄蝇C.(s.str.)illiberisi Chao et Liang,拟庸赘寄蝇Drino(Palexorista)inconspicuoides(Baranov),羚足鬃麻蝇S.(Sarcorohdendorfia)antilope B#x00F6;ttcher,共7种,其中蚕饰腹寄蝇、瘦钩鬃麻蝇、黑角狭颊寄蝇分布较广,种群数量较多,寄生率较高,分别为7.44%、7.37%、5.48%,被认为是优势种;且拟庸赘寄蝇为福建新分布记录;柳杉毛虫是黑角狭颊寄蝇、星毛虫狭颊寄蝇、拟庸赘寄蝇的新寄主;还发现2种重寄生蜂寄生于寄生蝇。记述柳杉毛虫的7种寄生蝇形态特征,有助于今后识别其天敌昆虫,研究害虫与天敌的种间关系,评价寄生蝇种群对维护柳杉林分生态系统稳定和防控柳杉毛虫的潜能,具有重要意义。  相似文献   

水合氧化铁提前施用对持续淹水条件下水稻甲烷的减排效应   总被引：1，自引：0，他引：1  

任杰  唐璐  陈菊培  但建国 《热带作物学报》2018,39(4):635-640

水合氧化铁是一种弱晶质三价铁氧化物,可用来减少稻田甲烷（CH4）的排放。采用水稻盆栽试验,研究水合氧化铁的提前施用对持续淹水条件下水稻CH4排放的影响。结果表明:水合氧化铁在水稻移栽前47 d施用,加Fe处理的全生育期CH4总排放通量比对照减少17.52%,其CH4减排效应仅出现于水稻生长后期。在移栽后第70天,加Fe处理的根孔隙度、根表铁膜含量和单株根表铁膜数量均显著高于对照,而稻根产CH4速率则显著低于对照。因此,提前施用水合氧化铁能够通过促进植株介导的根表铁膜的形成抑制稻根的产CH4潜力,进而实现持续淹水条件下水稻CH4的减排。  相似文献   

蚯蚓养殖对幼龄胶园土壤养分及橡胶树根系生长的影响     

李艺坚  谢学方  孔令泽  丰明 《热带作物学报》2018,39(7):1259-1265

本研究旨在探讨林下蚯蚓养殖对幼龄胶园土壤养分及橡胶树根系生长的影响。以牛粪作为原料,于 2017 年 4—11 月在 4 年生幼龄胶园铺设粪垄养殖蚯蚓,并测定土壤养分和根系生长情况。结果表明,与对照（CK）相比,铺设粪垄无蚯蚓养殖（WQ）和铺设粪垄蚯蚓养殖（Q）处理总体上可显著提高土壤硝态氮、速效磷、速效钾和土壤水分含量以及土壤 pH,而对土壤铵态氮、有机质、微生物活性及微生物群系数量无显著影响（p<0.05）;和 CK 相比,WQ和 Q 处理显著促进根的生长,并提高吸收根的比例（p<0.05）。综上所述,在幼龄胶园养殖蚯蚓短期内（半年）可提高土壤速效养分含量,促进根系生长。  相似文献   

油菜素内酯对小麦幼苗根系发育的影响   总被引：2，自引：0，他引：2  

邓茜  张爱华  侯立江  王丹  许盛宝 《麦类作物学报》2018,(12):1504-1511

为探究油菜素内酯（BL）对小麦幼苗根系发育的影响,以两个小麦品种中国春和辽春10号为实验材料,通过水培方法分析了不同浓度外源BL（0 nmol·L^-1、5 nmol·L^-1、25 nmol·L^-1、100 nmol·L^-1、1 μmol·L^-1）和BRZ（BR合成抑制剂,100 nmol·L^-1、1 μmol·L^-1和10 μmol·L^-1）处理下小麦幼苗根系的形态、长度、直径、侧根、侧根原基及其长出速率的差异。结果表明,经过不同浓度的 BL和BRZ处理后,两个小麦品种的幼苗地上部生长发育没有明显的差异,但是根系发育发生了显著的变化。较低浓度的BL（5 nmol·L^-1）处理会使根长增加,但高浓度BL（100 nmol·L^-1 、1 μmol·L^-1）处理会使根系伸长生长受到极显著的抑制;随着BL浓度的增大,根系直径越来越小。BRZ处理后小麦根系发育表现出相反的趋势,进一步证明BR激素对小麦根长、根径与侧根发生过程具有重要调控作用。细胞学观察的结果表明,BL主要通过调控根成熟细胞长度变化来影响小麦幼苗根系伸长生长。  相似文献