球针壳属—中国新记录种

报道了寄生于茄科中国枸杞(Lycium chinense Mill.)的球针壳属中国新记录种——丘布特球针壳(Phyllactinia chubutiana),其闭囊壳黑褐色,扁球形;附属丝8～10根,生于闭囊壳的赤道区,长度是闭囊壳的1～2倍,具球根状基部,顶部稍尖;子囊13～18个.每个子囊内有2个子囊孢子,卵圆形.无性态为Ovulariopsis insolita,分生孢子梗单生,直立,圆柱形;分生孢子单生,顶部无乳突,圆柱形,孢子萌发时形成粗的芽管并且顶端稍膨大;附着胞乳头状突起,具分叉或不规则状分支.标本保存在甘肃中医药大学植物保护标本室(HTCM 111022).     

吉林省枸杞白粉病病原菌鉴定

对枸杞白粉病病原菌形态进行详细观察,发现了引起枸杞白粉病的病原菌—穆氏节丝壳Arthrocladiella mougeotii。节丝壳属为吉林省新记录属,枸杞白粉病为吉林省新病害。另外还发现了枸杞上同时寄生有反卷白粉菌Erysiphe kenjiana,通过对采集环境、病菌分生孢子形态观察和萌发试验的研究分析,确定这种寄生现象为"假寄生"。     

南瓜白粉病病原菌鉴定及寄主范围测定

通过对南瓜白粉病病原菌的闭囊壳、分生孢子及萌发方式的观察和鉴别寄主感病反应鉴定,结果表明引起甘肃省武威地区南瓜白粉病的病原菌为苍耳单囊白粉菌Podosphaera xanthii。该白粉病菌闭囊壳形成的最适条件为温度20℃、相对湿度70%和光照强度4,400lx。寄主范围测定结果表明,该病菌不侵染丝瓜、小麦、辣椒、番茄、苜蓿、红三叶草、架豆和菜豆,可侵染除丝瓜之外的其余9种瓜类植物和绿豆、红小豆、向日葵,其中对南瓜、绿豆、西葫芦、红小豆、向日葵、甜瓜和黄瓜的致病性最强,发病率均达到100%,病情指数分别为15.56、14.51、13.33、13.33、13.07、12.22和12.22。侵染过程观察发现,感病南瓜人工接种白粉菌12h后,分生孢子芽管从侧面萌发,于24h芽管伸长,于36h形成菌丝,于72h形成稠密的网状菌丝,于96h形成分生孢子梗及串生分生孢子。     

吉林省香菜一新病害——白粉病

通过病害症状和病原形态学特征对吉林省香菜种植区白粉病病原菌进行鉴定,结果为该病由独活白粉菌（Erysiphe heraclei DC．）引起。香菜白粉病为吉林省香菜一新病害,且芫荽属为东北地区白粉菌属级新记录寄主。     

球针壳属一中国新记录种

报道了寄生于茄科中国枸杞(Lycium chinense Mill.)的球针壳属中国新记录种——丘布特球针壳(Phyllactinia chubutiana),其闭囊壳黑褐色,扁球形;附属丝8~10根,生于闭囊壳的赤道区,长度是闭囊壳的1~2倍,具球根状基部,顶部稍尖;子囊13~18个。每个子囊内有2个子囊孢子,卵圆形。无性态为Ovulariopsis insolita,分生孢子梗单生,直立,圆柱形;分生孢子单生,顶部无乳突,圆柱形,孢子萌发时形成粗的芽管并且顶端稍膨大;附着胞乳头状突起,具分叉或不规则状分支。标本保存在甘肃中医药大学植物保护标本室(HTCM 111022)。     

桑椹肥大性菌核病病原菌生物学特性及流行性

【目的】对桑椹灾害性真菌病害——桑椹肥大性菌核病病原菌,即桑实杯盘菌(Ciboria shiraiana)的生物学特性进行研究,分析其流行性。【方法】采用人工接种、调查等研究方法,对C.shiraiana在无性生长阶段中菌丝侵染能力,菌核的休眠期,有性生长阶段中子囊孢子的结构、释放、数目以及萌发等进行研究,并对菌核萌发的物候期进行调查。【结果】C.shiraiana菌丝对桑雌花没有侵染能力;C.shiraiana菌核具有休眠期,低温处理6周以上的菌核才能萌发形成子囊盘;1个菌核可萌发1–15个子囊盘,直径为1.5 cm的子囊盘能产生高达(5.6–6.3)×10~7个子囊孢子;C.shiraiana子囊孢子在酸性环境中的萌发率明显高于在中性和碱性环境中的萌发率;C.shiraiana菌核萌发形成子囊盘产生子囊孢子的物候期,从1月下旬开始到4月中旬结束,其中在3月中旬萌发子囊盘的数目达到最高值。【结论】桑椹肥大性菌核病属于典型的流行性侵染病,在果桑栽培上容易造成毁灭性危害,生产上必须高度重视该病的防控。     

瓜类白粉病的生物防治研究进展

白粉病是危害瓜类作物最为严重的一种气传病害,引起该病的病原菌为单囊壳白粉菌Podosphaera xanthii(synonym Podosphaera fusca)和二孢白粉菌Golovinomyces cichoracearum(synonym Erysiphe cichoracearum),其中对Podosphaera xanthii的报道较为常见。主要概述了瓜类白粉病病原菌的分类地位、病理特征和生物防治方面的研究进展,重点阐述了微生物源生防制剂和植物源生防制剂对瓜类白粉病的防治成果,并对当前研究与应用中存在的问题进行了探讨,为该病的深入研究和有效防治提供参考。     

中国白粉菌属的分类研究II．小檗科、秋海棠科和蓝雪科上的新种、新变种和新组合

寄生于小集科、秋海棠科和蓝雪科上的白粉菌属(Erystphe)真菌过去早有报道。但无论国内、国外,往往都将这三个科上的白粉菌属真菌鉴定为 Erysiphe polygont (DC.) St-Am-种。我们对中国有关标本的研究结果表明,该三科寄主上的白粉菌既不同于 Erysiphe polygont(DC.) St-Am.,与其他已知种亦有显著不同,彼此之间也有明显差异。     

苜蓿假盘菌子囊孢子萌发特性及子实体超微结构观察

【背景】苜蓿假盘菌(Pseudopeziza medicaginis)侵染苜蓿叶片引起的褐斑病是苜蓿的重要病害之一。研究表明,该菌以子囊盘越冬,翌年释放子囊孢子完成初侵染,因此观察该菌子实体的超微结构特征,有利于进一步揭示子囊菌的侵染机制。【目的】明确P. medicaginis子囊孢子萌发、Ca2+信号途径是否参与调控附着胞形成;观察子囊孢子和子实体的超微结构特征。【方法】采用光学显微镜技术,研究不同碳、氮源和Ca2+/CaM信号途径对P. medicaginis子囊孢子萌发、附着胞形成的影响,并采用电镜技术观察子实体和子囊孢子的超微结构。【结果】碳、氮源有利于P. medicaginis子囊孢子的萌发,葡萄糖、麦芽糖、蔗糖、氨基乙酸、酵母粉、尿素、蛋白胨、硝酸铵、硝酸钠等碳、氮源诱导形成附着胞,以尿素诱导效果最明显;Ca2+不仅促进子囊孢子的萌发,显著诱导附着胞的形成,而且高于碳、氮源;10 mmol/L的Ca2+诱导效果最明显,随其浓度的增加,子囊孢子的萌发率和附着胞的形成率下降;低浓度Ca2+螯合剂EGTA诱导形成附着胞,≥1 mmol/L抑制子囊孢子的萌发,外源Ca2+或Ca2+载体A23187能够部分解除EGTA的抑制作用;磷酸酯酶抑制剂Neomycin、Ca2+通道阻断剂Nicardipine、CaM拮抗剂Chloropromazine完全抑制子囊孢子的萌发。成熟的P. medicaginis子实体突破寄主表皮,中间开裂露出子囊,子囊孔口无囊盖,呈横向裂口状。子囊孢子表面具有环形纹饰,细胞核色深,线粒体等细胞器数量多,脂类物质数量多且发达,胞内充满电子致密度高的物质。【结论】碳、氮源和Ca2+可诱导P. medicaginis子囊孢子形成附着胞,钙信号途径参与P. medicaginis子囊孢子的萌发和附着胞形成过程的调控。子实体突破寄主表皮外露呈开裂式,子囊顶端无囊盖,线粒体发达。该研究结果为P. medicaginis的深入研究提供重要细胞学事件。     

白粉菌BGP(TG)在不同抗性草地早熟禾叶片上的侵染过程观察

【背景】草地早熟禾(Poa pratensis)白粉病是气传性病害,种植抗病品种是防治白粉病最经济、环保和有效的方法。【目的】明确禾布氏白粉菌BGP(TG)在3个不同抗性草地早熟禾叶片上的侵染过程和乳突在草地早熟禾抗白粉病中起的重要角色。【方法】利用考马斯亮蓝染色结合显微镜观察的方法,对不同抗性的3个草地早熟禾品种进行白粉菌侵染过程观察,统计分生孢子形成次生芽管的速度、吸器和乳突的形成情况,分析白粉菌对不同抗性草地早熟禾侵染过程的差异。【结果】‘探险家’草地早熟禾病症较其他2个品种更为严重,禾布氏白粉菌BGP(TG)侵染不同抗性品种的侵染过程基本一致,但‘探险家’叶片上初生吸器形成早于其他2个品种;接菌1-2 d后,在‘太行’叶表面分生孢子形成5级芽管的速度显著低于‘探险家’和‘黑杰克’;接种1d后,‘太行’草地早熟禾有效乳突形成率显著高于‘黑杰克’(P<0.05),‘黑杰克’有效乳突形成率显著高于‘探险家’(P<0.05)。【结论】明确了白粉菌在草地早熟禾叶片上的侵染过程和乳突在草地早熟禾抵御白粉菌侵入过程中起的重要作用,为草地早熟禾白粉病的预防和防治提供了理论基础和参考...     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.     

Composition and diversity of bird communities in Swedish farmland–forest mosaic landscapes

CapsuleThe amount of forest (at local and landscape scales) and occurrence of residual habitats at the local scale are shown to be the major factors influencing bird community composition in farmland–forest landscapes in central Sweden.

Aims To investigate the importance of local habitat and landscape structure for breeding birds in farmland–forest landscapes in central Sweden.

Methods Breeding birds were censused at 292 points. A detailed habitat mapping was made within 300 m of the points. Within a 300–600 m radius only two major habitats (forests and arable fields) were identified.

Results Cluster analyses of bird communities identified three site types that also differed in habitat composition: (i) partially forested sites in forested landscapes; (ii) heterogeneous sites with residual habitats in mosaic landscapes; and (iii) field-dominated farmland sites in open landscapes. A total of 19 of 25 farmland bird species (restricted to farmland or using both farmland and forest) had the highest abundance in farmland sites with mosaics of forest and farmland, while only six farmland species had the highest abundance in field-dominated sites. The bird community changed from being dominated by farmland species to being dominated by forest species (common in forest landscapes without farmland) at small proportions (10–20%) of forest at the local scale. A major difference in habitat composition between heterogeneous and field-dominated sites was the occurrence of different residual habitats (e.g. shrubby areas and seminatural grasslands). These habitats seemed to influence bird community composition more than land-use, despite covering <10% of the area. Seminatural grasslands were important for bird community composition and species-richness, but grazing seemed to be less important. Among different land-use types, cereal crops were the least preferred fields. Set-asides with tall vegetation and short rotation coppices were positively associated with species-richness of farmland birds.

Conclusion In general, the composition of the landscape was important for bird community composition, although amount and distribution of forests, occurrence of residual habitats and land-use of fields at the local scale had the strongest influence on bird community composition. The possible implications of these patterns for managing farmland–forest landscapes are discussed.     

Chemical constituents from the fruits of Rhus typhina L. and their chemotaxonomic significance

This work describes the isolation and characterization of twenty-nine compounds from the fruits of Rhus typhina L., including eleven flavonoids (1–11), eleven phenols (12–22), two pentacyclic triterpenes (23–24), two organic acids (25–26), one lumichrome (27), one courmarin (28) and one pyrimidine (29) on the basis of their spectroscopic data. Compounds apigenin (1), daidzein (4), orobol (5), 3′, 5, 5′, 7-tetrahydroxyflavanone (6), naringenin (7), butein (8), (-)-catechin (9), quercetin-3-O-α-L-(3″-O-galloyl)-rhamnoside (11), 2-hydroxybenzoic acid (13), 4-hydroxybenzaldehyde (14), vanillin (15), methyl 3,4-dihydroxybenzoate (16), 3,5-dihydroxybenzamide (18), tyrosol (19), caffeic acid (20), 3-(2,4,6-trihydroxyphenyl)-1-(4-hydroxyphenyl)-propan-1-one (21), phlorizin (22), friedelin (23), oleanolic acid (24), 4,4-dimethyl-heptanedioic acid (25), anthranilic acid (26), lumichrome (27), scoparone (28) and uracil (29) have not been recorded before in this plant. This is the first report on the occurrence of compounds 4–7, 9, 11, 13–14, 16, 18–21, 25–29 from the genus Rhus. Moreover, the chemotaxonomic significance of these isolated compounds was also summarized.