Linear-motion tattoo machine and prefabricated needle sets for the delivery of plant viruses by vascular puncture inoculation

Vascular puncture inoculation (VPI) of plant viruses previously has been conducted either manually or by use of a commercial engraving tool and laboratory-fabricated needle arrays. In an effort to improve this technique, a linear-motion tattoo machine driving industry-standard needle arrays was tested as a means of delivering plant viruses into maize and small grain seed embryos. The new method was applied in the successful transmission of maize rayado fino virus (MRFV), the type member of the genus Marafivirus, from an archived sample to maize. Subsequent transfer of MRFV from the sap of an infected plant using the method produced an average infection rate in maize of 70% (range 39–93%). Maize, oat, and triticale were successfully infected with oat blue dwarf virus (OBDV) using the method; similar infection rates were observed between maize seeds inoculated with the tattoo machine and those inoculated with the engraving machine when using prefabricated needle arrays. No infection was obtained in repeated tests with barley yellow dwarf virus (BYDV-PAV) or cereal yellow dwarf virus (CYDV-RPV) using either sap or RNA from infectious cloned cDNA. Replacement of the original engraving-tool with a linear-motion tattoo machine in VPI provides greater flexibility and convenience in a quiet, readily-available instrument, while improving reproducibility through the use of prefabricated needle arrays.     

陕西玉米病毒病及流行因素研究

 研究结果表明:陕西玉米病毒病毒原主要有玉米矮花叶病毒B株系(MDMV-B)、玉米粗缩病毒(MRDV)和大麦黄矮病毒(BYDV)。用血清鉴定225份病株样品中,MDMV-B、MRDV和BYDV侵染分别占40%、23%、4.5%。MDMV-B和MRDV复合侵染占23.5%。在田间自然条件下,MDMV-B主要通过玉米蚜和禾谷缢管蚜以非持久性传播,MRDV则由灰飞虱以持久传播。MDMV-B、MRDV和BYDV的粒子大小分别为735~755 nm×17 nm、70~75 nm和23~30 nm。随着玉米生育成熟,侵染逐渐降低,为害亦趋减轻。研究认为,玉米品种、播种期、播量、田间传毒介体数量及发生早晚和地膜覆盖等是影响玉米病毒病流行的主要因素。     

影响麦二叉蚜传播玉米矮花叶病毒效率的因素分析

玉米矮花叶病毒（ＭＤＭＶ）在田间主要依靠介质蚜虫非持久性方式传播,通过麦二叉蚜（Ｓｃｈｉｚａｐｈｉｓｇｒａｍｉｎｕｍ）对ＭＤＭＶ传毒效率影响因素的分析,发现接毒蚜获毒前禁食与否及禁食时间的长短与传毒效率呈高度正相关,从蚜量与传毒效率的关系来看,多头蚜虫的传毒效率均比单头蚜高,随着ＭＤＭＶ浓度和传毒蚜量的增加,传毒效率也随之提高,单蚜获毒１０ｍｉｎ后不禁食其传毒效率最高,随着禁食时间的延长,其传毒效     

玉米细菌干茎腐病菌成团泛菌的种子传播

为明确成团泛菌Pantoea agglomerans引起的玉米细菌干茎腐病经种子传播的规律,采用细菌常规分离法、Sherlock微生物鉴定系统、特异性分子检测技术,对与干茎腐病相关的杂交种金玉9856及其父本PS056、母本OSL190进行了种子带菌检测,证明金玉9856和PS056种子内部带菌,获得分离物Pagl和Pag2,2个分离物对感病的PS056均具有致病性.菌液浸种、种子注射接种和自然带菌种子直播都能够引发干茎腐病,发病率分别达到100%、100%和80%,而持续高温(50℃)处理4天的种子则在植株上不表现症状.对种子接种后长成的植株的系统检测证明,成团泛菌侵染种子后,通过植株维管束系统向地上部组织扩展,随着水分的运输,病菌通过茎秆到达果穗的籽粒中,完成从种子到植株、再到新种子的病害循环,同时能够引起植株发病.     

Characterization of maize streak virus: description of strains; symptoms

Twenty-four isolates of maize streak virus (MSV) derived from maize, sugarcane and grasses were compared to a maize isolate of the virus (M(N)M) from Nigeria, using symptoms, gel diffusion and ELISA. Fourteen isolates were identified as maize strains, eight other isolates were serologically related to M(N)M but were distinct. In most cases the maize strain could be identified by the symptoms in Zea mays cv. Golden Bantam but symptom expression in grasses was not always sufficient to identify the economically important maize strain. In general, however, symptoms were similar in both grass and maize hosts. Identification by symptoms alone was further complicated by the possibility that some isolates were mixtures. There was no evidence that adaptation to grass hosts occurred, as all isolates could be transmitted to maize. It was not possible to transmit certain strains to the host species from which they were derived, even though they were transmissible to other hosts. This was assumed to be related to vector feeding behaviour. Insect toxin was responsible for certain stunting symptoms, leaf curling and vein enations often associated with MSV.     

The occurrence and effects of barley yellow dwarf virus in maize in SW England

During 1975 and 1976 barley yellow dwarf virus was isolated, using the aphid Rhopalosiphum padi (L.) from five maize cultivars in the Exeter area. The isolates produced interveinal flecking, often accompanied by leaf reddening, in the maize cultivar Anjou 210 and several other susceptible cultivars. ln 1976 visual assessment of six commercial maize plantings indicated natural infections ranging from 11 to 14% of plants, whilst infection in a disease observation plot ranged from 0.8 to 27.5%. Population counts for the three aphid vectors Sitobion avenae (F.), Metopolophium dirhodum (W.) and Rhopalosiphum padi (L.), associated with the crop, corresponded closely with the Rothamsted Insect Survey results from Starcross, Devon.
The maize cultivars Anjou 210 and De Kalb 202 were grown in experimental plots with individual rows containing 0, 25, 50, or 100% barley yellow dwarf-infected plants. Infection caused severe stunting of Anjou 210 but had less effect on De Kalb 202. Dry matter yield losses of 50% for Anjou 210 and 27% for De Kalb 202 were recorded; there were also significant changes (p<0.05) in dry matter content, metabolisable energy, digestible crude protein and water soluble carbohydrate.     

浙江省水稻病毒病的发生规律和防治

 本文总结了1965-1977年水稻病毒病主要是黑条矮缩病、普通矮缩病的发生规律和传毒昆虫传病特点等方面的调查研究工作。
水稻黑条矮缩病由灰稻虱传播。灰稻虱能把病毒自水稻传到水稻、大小麦、玉米,但难以把病毒从玉米传到其它寄主上。已证实田间早熟禾可以作为黑条矮缩病无症带毒寄主。     

Biological characteristics of maize dwarf mosaic potyvirus from Spain

Two isolates of maize dwarf mosaic virus (MDMV-Sp and MDMV-Spl) obtained from maize in the northeast of Spain were studied. Both isolates induced similar reactions on 6 sorghum cultivars, johnsongrass and oat (cv. Clintland), with the exception of MDMV-Sp which produced a different reaction on one sorghum cultivar. Thirty-three grass species were tested as possible hosts (16 previously untested) and 18 were found to be susceptible. Among those, eight were previously unidentified hosts for MDMV:Aegilops ovata, A. ventricosa, Avena barbata, Bromus alopecurus, B. diandrus, B. fasciculatus, Echinaria capitata andLolium rigidum. Both isolates were transmitted from maize to maize nonpersistently byRhopalosiphum maidis, R. padi, Schizaphis graminum andSitobium avenae. The virus was not seed-transmitted in Mo17 and B73 maize inbred lines. Pinwheels, scrolls and short curved laminated aggregates were observed in the cytoplasm of maize cells infected by MDMV-Sp or MDMV-Sp1. In addition, laminated aggregates were observed in cells infected by MDMV-Sp1.     

Maize fine streak virus, a New Leafhopper-Transmitted Rhabdovirus

ABSTRACT A previously uncharacterized virus was isolated from fall-planted sweet corn (Zea mays L., Syngenta GSS 0966) leaves showing fine chlorotic streaks. Symptomatic plants were negative in enzyme-linked immunosorbent assay against many maize viruses, but reacted weakly with antisera to Sorghum stunt mosaic virus suggesting a distant relationship between the viruses. The virus was readily transmitted by vascular puncture inoculation (VPI), but not by leaf-rub inoculation. Symptoms on maize included dwarfing and fine chlorotic streaks along intermediate and small veins that developed 12 to 17 days post-VPI. The isolated virus was bacilliform (231 +/- 5 nm long and 71 +/- 2 nm wide), with a knobby surface, and obvious helical structure typical of rhabdovirus morphology. Nucleorhabdovirus virions were observed by transmission electron microscopy of infected maize leaf tissue sections. Proteins unique to infected plants were observed in extracts of infected leaves, and the isolated virion contained three proteins with molecular masses 82 +/- 2, 50 +/- 3, and 32 +/- 2 kDa. Preliminary sequence analysis indicated the virus had similarity to members of the family Rhabdoviridae. The virus was transmitted by Graminella nigrifrons under persistent conditions. The data indicate the virus, provisionally designated Maize fine streak virus, is a new species in the genus Nucleorhabdovirus.     

小麦/玉米带田不同玉米群体结构对光合特性的影响

对小麦/玉米复合群体中不同玉米群体的叶面积指数、光合速率及产量要素间的关系进行研究,结果表明:不同玉米群体的叶面积指数和光合速率的变化趋势均呈抛物线型,二者呈显著正相关;光合速率与经济产量相关极显著;两种带型中,6行小麦2行玉米,玉米密度为6.75万株/hm2的玉米群体平均光合速率最大,经济产量最高,6行小麦3行玉米,...     

Real-time weed detection, decision making and patch spraying in maize, sugarbeet, winter wheat and winter barley

Information on temporal and spatial variation in weed seedling populations within agricultural fields is very important for weed population assessment and management. Most of all, it allows a potential reduction in herbicide use, when post‐emergence herbicides are only applied to field sections with weed infestation levels higher than the economic weed threshold; a review of such work is provided. This paper presents a system for site‐specific weed control in sugarbeet (Beta vulgaris L.), maize (Zea mays L.), winter wheat (Triticum aestivum L.) and winter barley (Hordeum vulgare L.), including online weed detection using digital image analysis, computer‐based decision making and global positioning systems (GPS)‐controlled patch spraying. In a 4‐year study, herbicide use with this map‐based approach was reduced in winter cereals by 60% for herbicides against broad‐leaved weeds and 90% for grass weed herbicides. In sugarbeet and maize, average savings for grass weed herbicides were 78% in maize and 36% in sugarbeet. For herbicides against broad‐leaved weeds, 11% were saved in maize and 41% in sugarbeet.     

玉米白斑病的症状识别与诊断

由宽颈附球孢菌Epicoccum latusicollum Qian Chen, Crous & L. Cai引起的玉米白斑病正在我国局部地区流行, 导致重大损失, 并有扩大流行范围的趋势。为了增加植保及玉米抗病育种工作者对玉米白斑病的了解, 本文描述了该病害的症状特点、病原菌特征, 总结了发生规律、病害循环及分离鉴定和诊断技术。玉米白斑病菌能在病残体上越冬, 种子带菌是其远距离传播的主要途径, 风夹雨、昆虫及农事操作人员活动是近距离传播途径。7月中下旬至9月中下旬是白斑病流行高峰期, 病菌与玉米适宜生长温度基本一致, 具有扩散传播的风险。     

A histological assessment of the infection strategy of Exserohilum turcicum in maize

Northern leaf blight is a lethal foliar disease of maize caused by the fungus Exserohilum turcicum. The aim of this study was to elucidate the infection strategy of the fungus in maize leaves using modern microscopy techniques and to understand better the hemibiotrophic lifestyle of E. turcicum. Leaf samples were collected from inoculated B73 maize plants at 1, 4, 9, 11, 14 and 18 days post-inoculation (dpi). Samples were prepared according to standard microscopy procedures and analysed using light microscopy as well as scanning (SEM) and transmission electron microscopy (TEM). Microscopic observations were preceded by macroscopic observations for each time point. The fungus penetrated the leaf epidermal cells at 1 dpi and the disease was characterized by chlorotic leaf flecks. At 4 dpi the chlorotic flecks enlarged to form spots, and at 9 dpi hyphae were seen in the epidermal cells surrounding the infection site. At 11 dpi lesions started to form on the leaves and SEM revealed the presence of hyphae in the vascular bundles. At 14 dpi the xylem was almost completely blocked by hyphal growth. Hyphae spread into the adjacent bundle sheath cells causing cellular damage, characterized by plasmolysis, at 18 dpi and conidiophores formed through the stomata. Morphologically, lesions started to enlarge and coalesce leading to wilting of leaves. This study provides an updated, detailed view of the infection strategy of E. turcicum in maize and supports previous findings that E. turcicum follows a hemibiotrophic lifestyle.     

基于气象关键因子的河南省夏玉米产量预报研究

以河南省13个地市1990-2006年逐旬光温水气象资料为基础,通过相关分析确定了影响河南省夏玉米产量的关键气象因子,建立了7月中旬-9月中旬的夏玉米气象产量预报模型。将全省由南至北划分为三个区域,分区回代1990-2006年资料对模型预报准确率进行回代检验,并利用2007-2010年资料对模型进行试报。检验结果表明,模型回代准确率全省为88．4％,不同区域间回代准确率差异明显,北部最高92．9％,中部次之87．4％,南部最低83．4％,分析原因主要受夏玉米产量年际波动的影响;模型预报准确率全省为94．9％,各区域差别不大,基本在95％左右。     

Transmission efficiency of three isolates of maize stripe tenuivirus in relation to virus titre in the planthopper vector

Isolates of maize stripe tenuivirus (MSt V) from Florida (US), Costa Rica (CR), and Nigeria, Africa (AF), were transmitted to maize plants by the planthopper Peregrinus maidis (from Hawaii) with respective frequencies of 0,18, and 60% after a 1-day acquisition access period on diseased plants, and with frequencies of 18, 71 and 93%, respectively, after a 7-day access period. These isolates were transmitted transovarially to progeny planthoppers with respective frequencies of 21, 32, and 47%. The latent period in the vector, following oral acquisition of MSt V, was significantly longer in the US isolate than in the AF-or CR isolates. ELISA tests of MSt V-inoculative planthoppers indicated a significantly lower titre of MSt V-US compared with MSt V-CR or MSt V-AF. These results suggest that, compared with the US isolate, the AF and CR isolates of MSt V multiply faster and reach higher levels in, and are transmitted more efficiently by, P. maidis from Hawaii.     

Seed transmission of maize downy mildew (Peronosclerospora sorghi) in Nigeria

In an area of Nigeria where downy mildew of maize is present, histological assessment of maize seed revealed the presence of mycelium and oospores of Peronosclerospora sorghi in the kernels. Seed transmission of downy mildew of maize was demonstrated when grain purchased at local markets gave mean seedling infection rates of 12·3% (untreated seeds) and 10·0% (in metalaxyl-treated seeds) within 7 days of emergence, after storage in a desiccator for 30 days. When untreated seeds taken from nubbin ears of systemically infected plants from four states in southern Nigeria were planted at 9 days (17–22% moisture content) and 27 days (9–22% moisture content) after harvest, 20·0% infected seedlings resulted in both trials. Seeds from Borno state in northern Nigeria had 26·6% systemic seedling infection after 9 months of storage at 11% moisture content. When seeds harvested from maize plants inoculated with P. sorghi through silks were examined histologically, hyphae of P. sorghi were observed mostly in the scutellum of the embryo. Transmission of disease to seedlings was observed when the silk-inoculated seeds (9% moisture content) were planted in pots in a greenhouse; however, no disease transmission was observed when such seeds were planted in the field. The epidemiological significance of seed transmission is discussed with particular reference to survival of inoculum and development of epidemics. Also noteworthy is the overall significance of seed transmission in Nigeria, where the major source of seed is that saved by farmers from their grain crop, occasionally supplemented by seed bought from the local market.     

黄淮海地区夏玉米对干旱和涝渍的生理生态反应

利用黄淮海地区多站点的夏玉米水分控制试验,探讨旱涝对夏玉米发育进程、光合能力、干物质分配、叶面积扩展、产量结构及最终产量的影响,进而分析旱涝对夏玉米生长过程的影响机制。结果表明:干旱减缓了夏玉米营养生长阶段的发育速率,但加快了生殖生长阶段的发育进程,而涝渍对夏玉米发育进程的影响较小;夏玉米全生育期土壤湿度距适宜湿度减小1%,其叶片最大光合速率将下降0.3 mol·m~(-2)·s~(-1),比叶面积上升8×10-6hm~2·kg~(-1);夏玉米全生育期土壤相对湿度下降1%,其地上总干重和穗干重均下降0.55%,而产量将减少155kg·hm~(-2);干旱不仅使玉米灌浆时间变短,而且使叶片光合能力下降;营养生长阶段干旱使干物质更多地分配向茎秆,导致叶面积扩展乏力,生殖生长阶段干旱减少干物质向贮存器官的分配而影响产量构成;尽管干旱使叶片变薄而促进其扩展,但仍不足以减缓干旱的整体负面影响,最终导致玉米减产;而涝渍主要使玉米叶片光合能力下降,并导致干物质向穗的分配减少而减产。     

草地贪夜蛾在玉米单作及玉米-大豆间作田的扩散规律

草地贪夜蛾Spodoptera frugiperda (J.E.Smith)是新入侵我国的一种重大致灾性害虫,对我国玉米生产构成严重威胁.本研究于2019年和2020年在田间调查研究了草地贪夜蛾在玉米单作以及玉米-大豆间作模式下的田间扩散规律.结果 表明:草地贪夜蛾幼虫在2019年的36 m2和2020年的64 m2小...     

甘蔗花叶病毒在玉米种子中的分布及其与种子传毒的关系

 采用免疫学、电镜观察、RT-PCR、组织培养及生物学测定等方法,针对引起玉米矮花叶病的甘蔗花叶病毒(Sugarcane mosaic virus,SCMV)在高感自交系Mo17的乳熟期、蜡熟期、成熟期和室温贮存的成熟干种子上的分布部位及其各部位病毒的侵染性进行了研究。结果表明:病毒存在于种皮、胚乳的糊粉层和胚内,糊粉层和胚内的病毒具有侵染活力,胚内的可侵染性病毒可以通过发芽传递给下一代幼苗,完成病毒的种子传播过程。在种皮内没有检测到具有侵染活力的病毒,在胚乳的淀粉层内未检测到病毒。在种子成熟过程中,种子内的病毒不断得到积累,随着种子的脱水、干燥又被部分钝化,使得种子传毒率降低。