Truncatella angustata associated with grapevine trunk disease in northern Iran

In recent years, grapevine trunk diseases have gained growing attentions due to worldwide incidence of the disease. In a survey on fungal agents associated with grapevine trunk diseases in northern Iran, wood samples were collected from grapevines having the symptoms of declination. Isolation was made using routine plant pathology methods. A coelomycetous fungus with appendage-bearing conidia was recovered from symptomatic tissues. Based on morphological and cultural characteristics, the causal agent of the disease was identified as Truncatella angustata. The identity of the species was further confirmed by sequence data of internal transcribed spacer-rDNA region. A phylogeny inferred using sequence data obtained in this study, together with the sequences from GenBank, clustered our isolates together with T. angustata known from other host plant species. Pathogenicity tests performed on detached shoots of grapevines led to the same symptoms as observed in field conditions. This is first study on the pathogenicity of T. angustata on grapevine in Iran and first report on the occurrence of T. angustata on grapevine in Iran.     

Transmission of Grapevine virus A and Grapevine leafroll‐associated viruses 1 and 3 by Planococcus ficus and Planococcus citri fed on mixed‐infected plants

The Grapevine virus A (GVA) and Grapevine leafroll‐associated viruses 1 and 3 (GLRaV‐1 and GLRaV‐3) are associated with grapevine diseases that induce severe reductions in yield and berry quality. These three viruses are known to coexist in both grapevine and insect vectors, but their cotransmission has been poorly characterised so far. This study investigates the acquisition and transmission of GLRaV‐1, GLRaV‐3 and GVA by Planococcus ficus and Planococcus citri (Hemiptera: Pseudococcidae) following feeding on multiple‐infected plants. The retention and load of the three viruses in the two insect species were analysed. After feeding onto GVA, GLRaV‐1 and GLRaV‐3 mixed‐infected grapevines, nymphs of P. ficus and P. citri showed similar virus acquisition rates and retained low quantities of viruses until the third post‐acquisition day. Despite the similar acquisition patterns, the two vectors differed in transmission efficiency: P. ficus showed a higher efficiency in transmitting GVA and GLRaV‐3, whereas P. citri transmitted GLRaV‐1 more efficiently. When focusing on the virus cotransmission, it appears that GVA could be transmitted to grapevine without GLRaV‐1 and/or GLRaV‐3 and that the transmission of both GLRaVs could take place in the absence of GVA. This comparative study involving different viruses and vector species improves the current knowledge of the semi‐persistent transmission of these three viruses and contributes to the understanding of grapevine virus epidemiology.     

Siberian spruce tree ring anatomy: imprint of development processes and their high-temporal environmental regulation

Wood anatomy was offered as spatiotemporal proxy record for tracheid differentiation kinetics due to its advantages in terms of much longer cover period and less demanding measurements. In this study, external and internal regulation of earlywood-to-latewood transition and properties of latewood of Picea obovata Ledeb were considered. The values and interrelations between cell number, tree ring width, maximal and mean radial cell diameter, maximal cell wall thickness and position of the transition to thick-walled tracheids were investigated within site and along the altitudinal gradient. Correlations with moving 21-day climatic series were used to estimate high-resolutional external influences. Relationships between tree ring traits are spatially stable and close within one stage of differentiation and between cells production and expansion. Relationships between sites differ in upper and lower parts of the gradient. Most of traits respond to the primary limiting factors near summer solstice; however, maximal cell wall thickness responds positively to the temperatures at the + 10 °C threshold. Altitudinal anatomical patterns revealed interaction of intrinsic and external factors in the regulation of tracheid differentiation. Timing of climatic response highlighted role of photoperiod as a trigger in the earlywood-to-latewood transition, and crucial role of the growth season ending for latewood development.     

The origin of herbivory on land： Initial patterns of plant tissue consumption by arthropods

The early fossil record of terrestrial arthropod herbivory consists of two pulses. The first pulse was concentrated during the latest Silurian to Early Devonian （417 to 403 Ma）, and consists of the earliest evidence for consumption of sporangia and stems （and limited fungivore borings）. Herbivorization of most of these tissues was rapid, representing 0 to 20 million-year （m.y.） lags from the earliest occurrences of these organs in the fossil record to their initial consumption （Phase 1）. For approximately the next 75 m.y., there was a second, more histologically varied origination and expansion of roots, leaves, wood and seeds, whose earliest evidence for herbivorization occurred from the Middle-Late Mississippian boundary to the Middle Pennsylvanian （327 to 309 Ma）. The appearance of this second herbivory pulse during the later Paleozoic （Phase 2） is accompanied by major lags of 98 to 54 m.y. between times of appearance of each of the four organ and tissue types and their subsequent herbivory. Both pulses provide a context for three emerging questions. First is an explanation for the contrast between the near instantaneous consumption of plant tissues during Phase 1, versus the exceptionally long lags between the earliest occurrences of plant tissues and their subsequent herbivorization during Phase 2. Second is the identity of arthropod herbivores for both phases. Third is the cause behind the overwhelming targeting of seed-fern plant hosts during Phase 2. Regardless of the answers to these questions, the trace fossil record of plant-arthropod associations provides primary ecological data that remain unaddressed by the body-fossil record alone.     

NAGase activity in airborne biomass dust and relationship between NAGase concentrations and fungal spores

Inhalation of airborne fungal spores or fungalenzymes may cause adverse pulmonary healtheffects. The enzyme NAGase(N-acetyl--D-glucosaminidase) is achitinase presumed to be secreted by all fungi. In this study, NAGase activities andconcentrations of fungi are estimated inairborne biomass dust to acquire knowledgeabout the level of NAGase activity and therelationship between NAGase activity andconcentrations of airborne fungal spores.NAGase was sampled on both teflon andpolycarbonate filters, and polycarbonatefilters proved to be better for extraction ofNAGase than teflon filters. NAGase was foundin airborne dust at a biofuel plant and in dustgenerated from biomass. At a biofuel plant, themedian level of exposure to NAGase was 21 pmols^–1 m^–3. Significant correlationswere found between NAGase activities, totalnumber of fungal spores and CFU of fungi, withthe highest degree of correlation being betweenthe total number of fungal spores and theNAGase activity (r = 0.802, n = 76). Furthermore,when dust was stored for different periods, theculturability of fungal spores was stronglyreduced and the NAGase activity was not or onlyslightly reduced after up to 40 days ofstorage. Accordingly, NAGase activity may beused as a rapid method to get an estimate ofthe exposure level to airborne fungal spores.Whether pure NAGase or the NAGaseconcentrations observed here cause any healtheffects is not known, although it has beenshown that other fungal enzymes can causerespiratory disorders and a chitinase isdescribed as an allergen.     

Ontogeny of the vascular system ofBotrychium multifidum (S. G. Gmelin) Rupr.(Ophioglossaceae) and its bearing on stellar theories

Basipetal to the shoot apex, a procambial ring with parenchymatous gaps is present. The protoxylem poles are endarrh in both the ectophloic siphonostele and the collateral vascular bundle which comprises the leaf trace. Each leaf trace has an anastomosing system of protoxylem poles that decreases in number basipetally from five to three to two. Differentiation of the leaf trace procambium and protoxylem is bidirectional, that is the differentiation first occurs near the base of the leaf and acropetally in the leaf and basipetally in the stem. Then a fascicular cambium differentiates betweem the primary xylem and phloem in the leaf. This vascular cambium which is also present in the stem is unidirectional and only produces secondary xylem centripetally. Limited secondary growth also occurs in roots. Medullary tracheids when present are longitudinally continuous with the vascular system. The stele of the stem is interpretated as a sympodium of leaf traces and the pith is considered to be fundamental tissue enclosed by the anastomosing of leaf traces.     

Early Tertiary fossil plants and paleoclimate of Lanzhou Basin

Fossil plants from the lower part of Xianshuihe Formation in the Lanzhou Basin, Gansu Province were studied. The flora contains 29 species, representing 20 genera and 12 families, which include Lauraceae ( Daphnogene ), Lardizabalaceae ( Akebia ), Berberidaceae ( Berberis ), Ulmaceae ( Planera, Ulmus, Zelkova ), Betulaceae ( Alnus, Carpinus ), Myricaceae( Myrica ), Salicaceae ( Populus, Salix), Myrsinaceae(Ardisia), Rosaceae ( Prunus, Sorbus, Sorbaria, Spiraea ), Leguminosae ( Gleditsia, Sophora), Anacardiaceae (Rhus), Caprifoliaceae(Viburnum). An analysis of the floristic elements and their foliar physiognomy shows that most members of the flora are deciduous broad-leaved trees or shrubs with a few evergreen shrubs. The most noteworthy species is Rhus turcomanica which was present in the Middle Eocene to Late Eocene of Central Asia (Kazakhstan, Turkmenistan). Generally, Rhus turcomanica occurred at the same beds as Palibinia, an extinct fossil plant whose presence indicates a subtropical dry climate. Another species, Sorbaria callicomifolia Kornilova was present from the Early Oligocene to Early Miocene of Central Asia (Kazakhstan and Turkmenistan). According to an analysis of spores and pollen, this flora contains over 20 species. It is predominated by the angiosperm pollen. There appeared Ephedripites and Nitrariadites which were important elements in the dry area. Ephedripites was found from the Upper Cretaceous to Early Tertiary. Nitrariadites occurred in the Late Miocene, whereas Rhus turcomanica and Sorbaria callicomifolia were both reported in the subtropical dry area from the Middle Eocene to Early Oligocene. The latest record of Rhus turcomanica is from the Middle Eocene to Early Oligocene of Central Asia. The presence of this element in the lower part of Xianshuihe Formation may indicate that itsage is the latest stage of the Early Oligocene.     

Hamamelidaceae: Geographic Distribution,Fossil History and Origin

The family Hamamelidaceae is one of the core (or key) groups for studying the phylogeny of Hamamelids. It is an important taxon for the palaeobotanists and the botanists in discussing the origin and early evolution of the angiosperms owing to its strong differentiation of gross and pollen morphological characters. In this paper, the systematic position, modern distribution pattern and fossil history of the genera are analyzed, and the place and time of origin of the family are discussed according to the principle of the unity between the phylogeny and distribution of plants. The paper consists four parts.