Mortierella species from declining Araucaria araucana trees in Patagonia,Argentina

Since 2015, Araucaria araucana, an ecologically and economically important conifer native to Argentina and Chile, has suffered an unusual partial death of the crown throughout almost all of the distribution range in Argentina. No primary pathogen or pest was evident, associated with the phenomenon. Isolates of Mortierella, a poorly studied fungal genus in Patagonia, were obtained from the margins of necrotic phloem tissue of symptomatic trees. Five species of Mortierella were isolated from affected tissues. In inoculation tests, Mortierella alpina and M. aff. basiparvispora were pathogenic to A. araucana. These species caused necrosis of phloem, leading to chlorosis, foliar desiccation and eventually death, demonstrating that Mortierellales may play a role in the decline of the tree.     

Proteolytic activity in some Patagonian plants from Argentina

Six Patagonian plants were screened for proteolytic activity: Colliguaja integerrima, Euphorbia collina, E. peplus and Stillingia patagonica (Euphorbiaceae), Philibertia gilliesii (Asclepiadaceae) and Grindelia chiloensis (Asteraceae). P. gilliesii extracts showed the highest specific activity, followed by S. patagonica and E. collina. Proteolytic activity was unnoticeable in the other three species studied. Inhibition assays revealed that P. gilliesii and S. patagonica extracts contain cysteine-type peptidases and that in E. collina serine-type peptidases are present.     

Bioactive plants from Argentina and Bolivia

Antibacterial and molluscicidal activities of methanol and chloroform extracts of 16 plant species belonging to the families Compositae and Melastomataceae were evaluated. The chloroform extract of Vernonanthura tweediana and the methanol extract of Senecio santelisis resulted to be very toxic to brine shrimp nauplii (LC(50)=1 microg/ml). Chloroform extracts of S. santelisis and Senecio leucostachys as well as the methanol extract of Wedelia subvaginata displayed molluscicidal effects on Biomphalaria peregrina showing LC(100)<100 microg/ml. Moderate antibacterial action was produced by the chloroform extracts of Flaveria bidentis, Grindelia scorzonerifolia and Vernonia incana against two strains of Staphylococcus aureus.     

更新生态位及物种共存研究进展

更新生态位是一个新成熟个体成功代替另一个成熟个体所要求的可能生态位,是植物群落中物种共存的潜在机制和影响物种共存的关键因子;物种间能有效地分配生物和非生物资源而实现物种在时间和空间异质性的生境中共存;更新生态位分化表现为群落中共存物种间在较小时空尺度上的多种权衡;虽然共存物种间和种内个体竞争是森林群落物种共存的基本机制,但竞争和更新生态位分化并不矛盾,二者在不同的时空尺度上相互作用共同实现物种共存。     

Effects of fire disturbance on bird communities and species of mountain Serrano forest in central Argentina

In central Argentina, Serrano forest has a long history of fire disturbance; however, the impact of fire on avifauna remains unknown. We compared the avian–habitat relationships in forest patches with low, moderate, and high fire regimes using a community-level (species richness, abundance, ordination and guilds) and species-level (indicator species analysis) approach. In patches under each fire condition, we recorded bird community composition, richness and abundance, and different vegetation structure variables. The site under high-severity fire regime was structurally poor and had been converted from original forest to dense grassland. There, diversity of bird community was low, retaining approximately 30 % of the species present in the least impacted site. Avian assemblage was dominated by generalist and open area birds. Guilds were underrepresented, showing an important reduction of foliage granivorous, nectarivorous, omnivores, and foliage and bark insectivorous, and absence of fly-catchers. Moreover, low abundance of forest understory, midstory, and canopy species and of birds belonging to open and closed nesting guilds was detected. By contrast, under low and moderate-severity fire regimes highest bird diversity as well as highest representativeness of most guilds was observed. Forest bird species were strongly associated with low fire disturbance, whereas moderate fire disturbance was characterized by the presence of forest and generalist species. Given the critical conservation status of Serrano forest in Córdoba, Argentina, habitat restoration and protection of forest relicts could be suitable measures to promote avifauna preservation.     

Arbuscular mycorrhizal colonization of vascular plants from the Yungas forests, Argentina

In Argentina, the Yungas forests are among the ecosystems most affected by human activity, with loss of biodiversity. To assess the mycorrhizal status in these ecosystems, the roots of 41 native plant species belonging to 25 families were collected throughout the year from two sites of the Yungas forests. Roots were washed and stained to study the presence of arbuscular mycorrhizas (AM). Morphological types of arbuscular mycorrhizas (Arum and Paris-type) and colonization patterns were identified and photographed. All plants presented AM colonization. The AM colonization patterns varied from single intracellular aseptate hyphae, coils, appresoria, to vesicles and/or arbuscules. Among the species studied, the Paris-type colonization showed to be dominant. Results confirmed that AM hosts are predominant in the Yungas of South American forests.     

Occurrence of dark septate endophytes in Nothofagus seedlings from Patagonia,Argentina

Temperate forests of southern Argentina and Chile cover a wide latitudinal and altitudinal range on both sides of the Andes, with Nothofagus species being one of the main tree species. Most of the larger remnants are protected within the limits of national parks and forest reserves. However, some of these are invaded by exotic conifers such as Pseudotsuga menziesii. In order to better understand the mycorrhizal condition within the Nothofagus–P. menziesii interaction, transects were established at six study sites along the effective recruitment area. Three treatments were established: Nothofagus forest without P. menziesii invasion (Forest), Nothofagus–P. menziesii matrix (Interface) and P. menziesii plantation lacking Nothofagus specimens (Plantation). A 2 kg mixed soil sample was taken at each treatment site and kept in brand-new plastic bags. A soil bioassay with Nothofagus seedlings acting as baits was set to evaluate the mycorrhizal inoculum potential and soil-fungi composition at each sampling treatment. Forty percent of the evaluated seedlings were found to be colonised by dark septate endophytes (DSE) fungi. Ectomycorrhizal colonisation percentage was significantly higher in plants growing in Forest soils (mean = 57.77%) when compared with Interface (mean = 42.53%) and Plantation (mean = 44.65%). The high incidence of DSE in young roots of Nothofagus seedlings in this study supports the hypothesis that DSE might be pioneering colonisers of young tree seedlings in secondary successional environments. For future interventions in the forest, either with productive or protective intentions, it should be taken into account the incidence of these fungi, which may have an important positive role in Nothofagus forest post-invasion recovery.     

A new aromatic alkine from the tuber of Sparganium stoloniferum

A new aromatic alkine was isolated from the tuber of Sparganium stoloniferum . Its structure was assigned to be methyl 3,6-dihydroxy-2-[2-(2-hydroxyphenyl)-ethynyl]benzoate (1) by spectroscopic methods.     

A new aromatic glycoside from the roots of Prunus armeniaca

A new aromatic glycoside, 4-O-glycosyloxy-2-hydroxy-6-methoxyacetophenone (1), has been isolated from the roots of Prunus armeniaca.     

Association of seed‐borne Fusarium species on Pinus ponderosa with germination and seedling viability in Argentina

Pinus ponderosa seedlots from eight seed orchards in Western Patagonia, Argentina, were evaluated for the presence of Fusarium species, and isolates obtained were subjected to pathogenicity tests. The following species were isolated: Fusariumoxysporum, Fusarium equiseti, Fusarium verticillioides, Fusarium incarnatum, Fusarium acuminatum, Fusarium graminearum and Fusarium proliferatum. With the exception of F. proliferatum and F. graminearum all Fusarium species were recovered from P. ponderosa seedlings with symptoms of damping‐off. Five Fusarium species were re‐isolated from necrotic roots of seedlings showing chlorosis (F. oxysporum, F. equiseti, F. incarnatum, F. acuminatum and F. verticillioides). High damping‐off losses occurred in Fusarium‐contaminated seed of P. ponderosa and low disease incidence occurred on less contaminated seed. The role of seed‐borne inoculum in disease spread within forest nurseries is discussed.     

利用核糖体小亚基RNA序列探讨四种腹毛目纤毛虫的系统进化

以四个在环境监测中比较有代表性的纤毛虫属－游仆虫属、尾柱虫属、棘尾虫属和伪角毛虫属纤毛虫(Euplotes, Urostyla, Stylonychia, Pseudokeronopsis)为材料,对其16s小亚基核糖体RNA(16s－like Small Subunit rRNA,SSrRNA)基因进行序列测定,并与其他种腹毛目纤毛虫相比较,以美国赭虫(Blepharisma americanum)为外群构建系统进化树.结果显示:游仆虫属最先从腹毛目纤毛虫中分化出来,尾柱虫属(Urostyla)与全列虫属(Holosticha)纤毛虫亲缘关系较近.贻贝棘尾虫(Stylonychia mytilus)和浮萍棘尾虫(Stylonychia lenmae)是姊妹种,在外观上及其相似,但可以用构建进化树的方法从分子角度加以区分.从构建的进化树拓扑结构上可知,红色伪角毛虫与全列虫科种类的亲缘关系较近,与尾柱虫科种类的亲缘关系较远.     

中国重要外来入侵种─紫茎泽兰研究综述

紫茎泽兰(Eupatorium adenophorum Spreng.) 大约于20世纪40年代传入我国滇南地区,并在中国南部和西南地区快速蔓延,造成严重的经济损失。20世纪80年代率先在云南省开展了紫茎泽兰生物学特性及综合防治的研究。目前紫茎泽兰被国家环保总局列入危害最严重的十六种入侵生物的白皮书中。本文对二十多年来我国开展的有关紫茎泽兰的研究进行扼要的叙述,研究主要涉及以下几个方面:紫茎泽兰在中国的分布、生物学特性、生态学特性、化学成分、危害性、潜在的应用价值、控制方法和手段。此外,本文还探讨了今后研究的重点方向。     

Antibacterial activity of some medicinal plants from San Juan, Argentina

The antibacterial activities and preliminary phytochemical screening of 13 plants used as folk medicine in San Juan, Argentina, are reported.     

Absence of bacteria from the heartwood of eucalypt species

Bacteria were not detected in clear or decaying heartwood from four eucalypt species. This may be associated with an observed intolerance of sapwood isolates to the highly acidic conditions and abundant extractives in the heartwoods.     

Essential oils from two aromatic plants repel the tobacco whitefly Bemisia tabaci

Journal of Pest Science - Characterizing the olfactory responses of insect pests is critical for developing biological control options and pest management strategies in the field. Such responses...     

SPME法与SDE法测定雨花茶香气成分比较

分别采用SPME法与SDE法提取雨花茶中的香气成分,通过GC-MS定性定量分析,对两种方法所得的香气成分进行比较.结果表明,苯甲醇、苯乙醇、苯甲醛、香叶醇、芳樟醇及其氧化物、橙花醇等是构成雨花茶香气的重要物质,两种方法测出的相对含量都在2%以上.SDE法检测出的组分种类较多,相对含量较多的有32种,但高温剧烈反应使得部分原料香气物质发生变化,不能真实反应雨花茶的香气成分;SPME法检测到的挥发性物质较少,有20种,主要是低沸点的萜类、醛酮类和弱极性的烃类物质,基本能反应雨花茶的特色香味成分.     

不同功能区林下土壤多环芳烃分布特征及来源分析

以乌鲁木齐工业区、交通区、居民区和公园区的林带作为试验采样区,分别从各功能区林带土壤中多环芳烃(PAHs)的含量、组成、污染情况、来源4个方面,分析了土壤中16种PAHs污染特征。结果表明:乌鲁木齐不同功能区林下土壤平均PAHs的含量为(375.76±32.96)ng·g^-1,其中交通区>工业区>居民区>公园区。低环和高环PAHs含量分别占32.02%和67.98%。工业区林带和交通区林带土壤以4环和3环为主,居民区和公园区以5环为主。工业区和交通区林带土壤以轻度污染为主(42.90%和37.50%);而公园区和居民区以轻度污染(60.00%和66.67%)和未污染(40.00%和33.33%)为主。工业区林带土壤组分中占比最高和最低的分别是茚并(1,2,3-cd)芘(IcdP)占16.01%和?(Chr)占0.98%,交通区林带占比最高和最低的分别是荧蒽(Fla)占16.01%和苊(Ace)占0.49%,居民区林带分别是荧蒽(Fla)占15.66%和?(Chr)占0.21%,公园区林带分别是茚并(1,2,3-cd)芘(IcdP)占19.48%和?(Chr)占0.84%。以煤、木、草等生物质燃烧为污染源的样地最多的是公园区;以汽车尾气、石油燃烧为污染源的样地最多的是交通区。各功能区PAHs的来源主要为煤、生物质等的不完全燃烧。     

含笑种源引进及测定评价

在北亚热带宁镇丘陵地区和太湖孤山丘陵地区引种原产中亚热带丘陵山区5种含笑种源试验结果表明,幼龄期生长量乐昌含笑>金叶含笑>深山含笑>醉香含笑>阔瓣含笑;长沙种源苗期抗寒性深山含笑>乐昌含笑>醉香含笑;高温日灼抗性乐昌含笑>金叶含笑>阔瓣含笑>醉香含笑>深山含笑;对持续60d秋旱的抗性深山含笑>乐昌含笑>醉香含笑。除醉香含笑历年在-5℃条件下会产生明显冻害外,幼龄期供试其他各种含笑均能适应引种的气候及圃地立地条件,正常生长发育。在供试种源中,浙江杭州种源深山含笑和乐昌含笑生长较好,适应性强,是值得扩繁应用的优良种源。而醉香含笑适应性较差,不宜在宁镇丘陵地区引种。安徽黄山种源深山含笑长势较差,抗寒性、抗旱性较差,亦不宜继续引种。     

Mass propagation method from the cutting of three dipterocarp species

We developed a vegetative propagation system for mass-producing three dipterocarps species,Shorea selanica Bl.,Shorea leprosula Mig., andShorea platyclados Sloot. This system uses fog evaporative cooling inside a greenhouse to reduce the leaf-to-air vapor pressure deficit (leaf-to-air VPD) inside the propagator, even under high irradiance conditions. This cooling method has no negative influence on medium conditions such as overwetting. A plastic tent propagator combined with this cooling method was used for vegetative propagation experiments. In mass-production experiments, the annual rooting percentages from the cuttings were low in the first 2 years (1997–1998) due to operational problems of the tent propagator (S. selanica, 48–51%;S. leprosula, 56–59%;S. platyclados: 50–63%). A hard cover propagator improved the rooting percentages in the mass-production experiments in 1999 because it made operations easier (S. selanica, 70%;S. leprosula, 77%;S. platyclados, 77%). This system, which uses a combination of fog evaporative cooling and a hard plastic propagator, should be useful for the mass propagation of these dipterocarp planting stocks. This study was carried out under a joint project of the Ministry of Forestry, Indonesia and Komatsu Ltd. The project was supported by Research Association for Reforestation of Tropical Forest (RETROF) organized by Japanese Forestry Agency.     

A new Leptographium species from the roots of declining Pinus sylvestris in Switzerland

Scots pine (Pinus sylvestris) trees have been declining in the Rhône valley, Switzerland, for almost three decades. In an assessment of the role of fungi in this syndrome, the dominant fungus isolated from stained roots was a Leptographium species, morphologically similar to the asexual state of Grosmannia serpens. We examined isolates of this fungus based on DNA sequences of four protein‐coding genes including actin, β‐tubulin, calmodulin and translation elongation factor‐1 alpha. The results showed that they were of a distinct, undescribed taxon related to species in the Grosmannia serpens and G. wageneri complexes. The fungus, described here as Leptographium rhodanense sp. nov., resembles other species in the two species complexes morphologically, and most probably ecologically, as is suggested by the fact that it was isolated from stained pine roots.