Parasitic weeds of the Orobanchaceae family and their natural hosts in Jordan

A field survey of the Orobanchaceae family members and their hosts in Jordan was carried out from 2003 to 2007. The intensity of parasite infection on different hosts and the severity of the infestation were evaluated. The results showed the presence of seven species of Orobanche and three species of Cistanche . The Orobanche species were found parasitizing 86 plant species belonging to 24 botanical families. Most of the species attacked by Orobanche were from the Compositae (20 species), Solanaceae (11 species), Leguminosae (nine species), Umbelliferae (seven species), Cruciferae (seven species), Cucurbitaceae (four species), Labiatae (four species), and Rosaceae (four species) families. Other families were represented by one-to-three species. Cistanche attacked 20 species of forage wild shrubs, fruit trees, and forest trees of seven families, mostly belonging to the Chenopodiaceae (seven species) and Leguminosae (three species) families. Previously unreported hosts for both genera include: Amygdalus communis , Olea europaea , and Quercus coccifera , which were parasitized by Orobanche palaestina ; A. communis , O. europaea , Prunus armeniaca , and Prunus persica , which were parasitzed by Orobanche cernua ; O. europaea and A. communis , which were parasitzed by Orobanche schultzii ; Haloxylon persicum , which was parasitzed by Cistanche lutea ; Punica granatum , Alhagi maurorum , Casuarina equisetifolia , Centaurea postii , and Prosopis farcta , which were parasitzed by Cistanche tubulosa ; and Achillea spp., Anabasis syriaca , H. persicum , Haloxylon salicornicum, Suaeda spp., and Zilla spinosa , which were parasitzed by Cistanche salsa . Certain Orobanche species were completely destructive to the cultivated crops. The results indicated the high potential of both parasitic genera to spread and to attack new hosts, while the threat they impose to agriculture in Jordan will probably result from poor management and deficiences in farmers' training.     

Two species of Mentha as new hosts of Corticium rolfsii

Two species of Mentha were affected by collar rot and wilt in the Tarai region of Uttar Pradesh, India. The pathogen was isolated and identified as Corticium rolfsii , which is newly recorded on these hosts.     

大兴安岭南段白桦林降雨再分配特征研究

利用2013年度赛罕乌拉地区白桦林64场有效降雨及林内再分配的野外观测数据,探讨了该地区白桦林降雨再分配特征。结果表明:白桦林的穿透降雨量、树干茎流量和林冠截留量分别占同期林外降雨量的76.0%,2.3%,21.7%。穿透降雨量及树干茎流量与林外降雨量均呈明显的线性相关(R2=0.8800),而林冠截留量与林外降雨量呈指数函数关系(R2=0.8303)。实验证明当林外降雨量大于0.3mm时,可发生穿透降雨;林外降雨量大于0.51mm时,可发生树干茎流。林冠层叶面积指数(LAI值)及独特的立地条件、生长特征对降雨再分配起着重要的影响。     

New natural hosts of Tomato yellow leaf curl virus identified in and near tomato-growing greenhouses in eastern China

Tomato yellow leaf curl virus (TYLCV) causes huge losses to tomato production worldwide. In July 2011 and July–August 2012, we screened for potential TYLCV hosts in a tomato-growing area in Shandong Province, the core vegetable-producing region in China. PCR detection showed that 5 species of plants, Zinnia elegans, Acalypha australis, Gossypium hirsutum, Abutilon theophrasti, and Nicotiana tabacum, were infected. Full genomic sequences of the new TYLCV isolates were obtained and submitted for sequence analysis. Sequence alignment and similarity analysis showed that they all belonged to the TYLCV-IL strain.     

我国玉米上一个水稻黑条矮缩病毒重排体的ＯＲＦ序列(英文)

 玉米粗缩病20世纪50年代和90年代中后期在我国部分地区严重发生,2008年至今, 该病在黄淮海地区又呈暴发趋势^[1]。引起我国北方玉米粗缩病的主要是水稻黑条矮缩病毒(Rice black-streaked dwarf virus,RBSDV)^[2]。田间寄主植物和传毒昆虫灰飞虱(Laodelphax striatellus Fallen)的发生数量、带毒率与玉米粗缩病的发生密切相关^[1]。因此,建立快速灵敏的RBSDV检测体系,明确RBSDV的田间寄主,对有效控制玉米粗缩病具有重要意义。     

水稻黑条矮缩病毒检测体系的优化及田间寄主检测

 玉米粗缩病20世纪50年代和90年代中后期在我国部分地区严重发生,2008年至今,该病在黄淮海地区又呈暴发趋势［1］。引起我国北方玉米粗缩病的主要是水稻黑条矮缩病毒（Rice black streaked dwarf virus,RBSDV）［2］。田间寄主植物和传毒昆虫灰飞虱（Laodelphax striatellus Fallen）的发生数量、带毒率与玉米粗缩病的发生密切相关［1］。因此,建立快速灵敏的RBSDV检测体系,明确RBSDV的田间寄主,对有效控制玉米粗缩病具有重要意义。     

Diagnostic sensitivity and specificity of different methods used by two laboratories for the detection of Phytophthora ramorum on multiple natural hosts

Five detection methods were comparatively tested on putative Phytophthora ramorum field samples from 41 wild plant species. The tested methods included two culture‐based assays, a DAS‐ELISA‐based polyclonal assay, a nested PCR‐based assay, and a TaqMan real‐time PCR assay. Diagnostic values including sensitivity, specificity, positive predictive value and negative predictive value were calculated for each method. The effects of host species, seasonality and host location were analysed and compared between two laboratories. Significant effects of season, host species and laboratory were detected. It is concluded that a combination of either culturing and molecular diagnosis or of two molecular assays is the most promising approach to diagnose this pathogen. Based on the results of this and other studies, diagnosis should occur as much as possible during wet and warm periods favourable to the pathogen, and proficiency tests should be performed to compare results obtained with molecular approaches in different laboratories. Furthermore, length of time lapsed between sample collection and processing strongly affected the diagnostic sensitivity of culture‐based methods, and therefore needs to be taken into account when comparing results from different laboratories.     

Ultrastructure of developmental stages of Hemolivia mariae (Apicomplexa: Haemogregarinidae), natural parasite of the Australian sleepy lizard, in experimentally infected deviant hosts

Mabuya vitatta (Olivier) (Scincidae) and Agama stellio (L.) (Agamidae) were infected with Hemolivia mariae Smallridge et Paperna, 1997 by ingestion of tick viscera from Amblyomma limbatum Neumann, fed as nymphs on naturally infected Australian sleepy lizards, Tiliqua rugosa Gray. The unnatural infection apparently interfered with the developmental schedule of the parasites. Transmission electron microscopic images of merogonic stages were obtained, as well as images of early developing gametocytes. Tissue and intraerythrocytic meronts were bound by a hardened wall. Intraerythrocytic gametocytes were lodged in a parasitophorous vacuole, which was filled with granular material, and were bound by a two-membrane wall. Small and large osmiophilic bodies were located in a sub-pellicular position. With differentiation, the wall membranes tightened with the parasitophorous vacuole wall, and the osmiophilic bodies disappeared. The outer parasite membrane consolidated into a thick encasing with distinct sutures. Late infection in A. stellio comprised gametocytes only.     

Development and application of a PCR-based 'molecular tool box' for the identification of Phytophthora species damaging forests and natural ecosystems

A PCR-based 'molecular tool box', based on a region of the ras-related protein gene Ypt 1, was developed for the identification of 15 Phytophthora species that damage forests and trees: P. cactorum , P. cambivora , P. cinnamomi , P. citricola , P. europaea , P. inundata , P. lateralis , P. megasperma , P. nemorosa , P. kernoviae , P. pseudosyringae , P. psychrophila , P. quercina , P. ramorum and P. ilicis . Most primers proved highly specific in blast analyses and in tests with DNA from 72 isolates of 35 species of Phytophthora and nine species representative of Pythium . Exceptions were primers designed for P. cactorum and P. ilicis , which cross-reacted with P. idaei and P. nemorosa , respectively. Amplification with Phytophthora -genus-specific primers before amplification with the various species-specific primers (nested PCR) increased the sensitivity of detection over amplification with species-specific primers only: detection limits ranged between 100 and 10 pg target DNA µ L⁻¹ in the latter, compared with 100 fg µ L⁻¹ in nested PCR. Using existing methods for rapid extraction and purification of DNA, single-round amplification was appropriate for detection of target Phytophthora species in leaves, but nested PCR was required for soil and water samples. The quarantine pathogens P. ramorum and P. kernoviae were detected in a number of naturally infected leaves collected in England and Wales, whereas P. citricola was commonest in water and soil samples from natural Scottish ecosystems.     

Occurrence of powdery mildews on new hosts in Turkey

Erysiphe convolvuli onConvolvulus lanatus, C. pentapetaloides, C. siculus subsp.siculus andIpomoea sagittata; Erysiphe ranunculi onRanunculus marginatus var.trachycarpus; Erysiphe clandestina onUlmus minor subsp.canescens; Podosphaera fusca onConyza canadensis; andPodosphaera ferruginea onSanguisorba minor subsp.magnolii were identified and the associated host plants were found to be new for the Turkish mycoflora. http://www.phytoparasitica.org posting Sept. 17, 2006.     

Quantifying resistance to Plasmodiophora brassicae in Brassica hosts

Plasmodiophora brassicae causes clubroot of crucifers. A quantitative PCR (qPCR)‐based protocol was developed to measure P. brassicae DNA in the roots of susceptible, intermediately susceptible, intermediately resistant and resistant Brassica hosts, and the non‐host wheat, at 5, 10, 15, 20 and 42 days post‐inoculation (dpi). The final reaction of each plant genotype was recorded as an index of disease at 42 dpi. Plasmodiophora brassicae DNA showed an increase in susceptible and moderately resistant hosts from 5 to 42 dpi, in contrast to a decrease in a highly resistant host and the non‐host wheat over the same period. Index of disease was significantly positively correlated with the amount of P. brassicae DNA in the roots at 5, 15, 20 and 42 dpi in one experiment, and at 10, 15, 20 and 42 dpi in a repeated experiment. Significant positive correlations also existed between the amounts of P. brassicae DNA in the roots at 42 dpi and those at 5, 10, 15 and 20 dpi in one experiment, and those at 10, 15 and 20 dpi in a repeated experiment. The results generated by the qPCR assay were validated by microscopic examination of roots inoculated with P. brassicae. The qPCR‐based protocol developed in this study allows for the accurate quantification of P. brassicae DNA in host root tissues as early as 5 dpi, and may serve as a useful tool to evaluate pathogen proliferation and development in the roots.     

The adsorption and degradation of glyphosate in five Hawaiian sugarcane soils*

The rate of aerobic evolution of ¹⁴CO₂ from ¹⁴C-glyphosate labelled in the methylphosphonyl carbon, varied 100-fold within a group of five Hawaiian sugarcane soils. The rate depended inversely on the degree of soil binding, probably associated with the phosphonic acid moiety, and to a less certain extent on soil pH and soil organic matter. After an initial rapid degradation, the rate of ¹⁴CO₂ evolution in three soils reached a constant at 16–21 days which continued to the 60-day termination. The other two soils showed a continually decreasing rate throughout. Two soils released over 50% of the labelled carbon in 60 days, a third released 35%, while the remaining soils released 1.2 and 0.8% respectively. Labelled carbon in the soils after 60 days consisted of glyphosate and one metabolite, aminomethyl-phosphonic acid, with glyphosate predominating in high fixing soils. The ¹⁴C could be extracted almost completely with NaOH solution, and remained mainly in solution after acidification.     

Effect of different hosts onThaumetopoea pityocampa populations in northeast Portugal

A study was carried out at the Natural Park of Montesinho, NE Portugal, in order to evaluate the effect of different pine species (Pinus pinaster Ait.,P. nigra Arn. andP. sylvestris L.) onThaumetopoea pityocampa populations. The structure of the egg batches, the impact of the egg parasitoids on natural mortality of the pest and the species of parasitoids present, as well as their emergence dynamics, were analyzed. The length of the egg batches varied among pine species with the longest ones onP. nigra. The mean number of eggs per batch differed betweenP. sylvestris and the two other hosts studied, with fewer eggs per batch on the first. No differences were found in the size of eggs among pine species. The egg mortality varied between 25.8% and 33.0%, with no differences among hosts. Parasitism was the main cause of death.Baryscapus servadeii (Mercet.) was the most abundant parasitoid species, followed byOoencyrtus pityocampae (Dom.) andTrichogramma embryophagum Htg.B. servadeii dominated in the egg batches collected fromP. pinaster andP. nigra, whereasO. pityocampae was most frequent onP. sylvestris. The emergence ofB. servadeii started in the middle of March and continued until August, with the emergence peak at the end of May. The emergence ofO. pityocampae started at the end of April and continued throughout September, with maximum values in June. http://www.phytoparasitica.org posting Sept. 20, 2006.