链格孢菌毒素对紫茎泽兰的致病机理

以叶圆片法分析链格孢菌[Alternaria alternata(Fr.)Keissler]毒素对紫茎泽兰（Eupatorium adenophorum Spreng.)叶组织细胞膜透性、过氧化物酶（POD）、抗坏血酸过氧化物酶（APX）和过氧化氢酶（CAT）活性以及丙二醛（MDA）含量的影响,结果表明,链格孢菌毒素使紫茎泽兰叶组织细胞膜透性上升,Na^ 和K^ 渗漏量增加,膜脂过氧化加强,MDA含量上升;链格孢菌毒素处理的紫茎泽兰叶片中POD、APX和CAT的活性均较对照降低。     

水葫芦黑斑病菌Alternaria alternata的生物学特性研究

在不同试验条件下培养水葫芦黑斑病菌Alternaria alternata菌株,探讨其主要的生物学特性,结果表明：该菌株生长的最佳培养基为PSA,最佳C源为葡萄糖,弱碱性和中性N源对该菌菌丝生长具有明显的促进作用,而酸性N源对其具有抑制作用。菌株生长的最佳pH值为pH7,最适温度为27℃。湿度越大,对菌株生长越有利。     

Two cases of cutaneous phaeohyphomycosis by Alternaria alternata and Alternaria tenuissima

Two cases of cutaneous phaeohyphomycosis, one with a nodular appearance and the other with an erythematous infiltrating patch, are reported in immunocompromised patients. Diagnosis was based on histological examination, which revealed hyphae and round-shaped fungal cells in a granulomatous dermal infiltrate, and on identification of the moulds when biopsy fragments were cultured on Sabouraud-dextrose agar without cycloheximide. The pathogens were Alternaria tenuissima in the first case and A. alternata in the second. The fungi were examined by scanning electron microscopy. The patients were checked for bone and lung involvement and were then treated with surgical excision and itraconazole, and itraconazole only, respectively, with clinical and mycological resolution. This revised version was published online in August 2006 with corrections to the Cover Date.     

紫茎泽兰一种潜在化感活性物质的分离鉴定

【背景】紫茎泽兰潜在的化感效应可能是其具有极强入侵性的重要原因。目前,针对紫茎泽兰潜在化感活性物质的研究主要集中于偏小极性的萜烯类化合物,而对大极性化学物质的研究相对较少。【方法】采用活性跟踪分析法对紫茎泽兰乙酸乙酯提取物大极性亚组分进行潜在化感活性物质的跟踪分离,并用现代波谱技术解析其化学结构,最后就分离获得的单体成分与已报道的化感活性物质羟基泽兰酮（2）和泽兰二酮（3）以及信号分子JA-Ile在抑制拟南芥种子萌发和幼苗根生长方面进行潜在化感活性的对比分析。【结果】分离鉴定出一个具有潜在强化感活性的大极性化合物2．香豆酸葡萄糖苷（1）,研究发现该化合物虽然对拟南芥种子萌发的抑制作用不显著,但在0．1mmol·L^-1的浓度条件下对拟南芥幼苗根生长却有着比羟基泽兰酮和泽兰二酮更为显著的抑制活性,且其抑制作用的浓度一活性关系与信号分子JA-Ile类似。【结论与意义】紫茎泽兰中潜在大极性的非萜烯类化感活性物质对于紫茎泽兰的综合化感效应可能同样具有重要而不可或缺的作用,化合物1等潜在大极性化感活性物质的逐步揭示对于系统解析紫茎泽兰的化感效应机制具有重要意义。     

紫茎泽兰醇提物的毒理学研究

为确保以紫茎泽兰提取物为主要原药的植物源农药的安全性,对紫茎泽兰醇提物进行了小鼠经口急性毒性试验、大白兔急性皮肤和眼刺激试验、小鼠骨髓嗜多染红细胞微核计数及小鼠精子畸形试验等急性毒性和遗传毒性试验。结果表明,受试物对两种性别的小鼠经口急性毒性试验,LD50大于5000mg／kg,对大白兔皮肤无刺激性;小鼠骨髓嗜多染红细胞微核试验及小鼠精子畸形试验结果均为阴牲,受试物未见遗传毒性。     

入侵植物紫茎泽兰化感作用及其途径研究

紫茎泽兰广泛入侵中国西南地区,研究结果表明化感作用是其入侵的重要武器,但其化感作用的途径并不十分清楚。本研究中,我们发现紫茎泽兰可以通过多种途径对两种栽培植物大麦和玉米的生长产生化感作用,这些途径包括了叶挥发物、叶淋溶物以及根分泌物。并且在紫茎泽兰幼苗早期就可以检测到这些化感作用。然而,没有实验证据表明紫茎泽兰落叶的微生物降解物对两种测试植物具有化感作用。     

L型氨基酸对烟草赤星病菌毒素毒性的影响

为确定不同氨基酸对烟草赤星病菌产生的毒素毒性的影响,作者采用摩擦接种处理法、浇根处理法、种子根处理法三种生物测定方法,确定了以烟草种子根处理法作为烟草赤星病菌的毒性测定方法。用12种氨基酸分别以5种不同浓度与AT毒素混合接种,根长测定结果表明：L-谷氨酰胺,L-天冬酰胺,L-组氨酸所有供试浓度均增强病原菌毒素的毒性,而其余9种L型氨基酸对烟草赤星病菌GL-6产生的毒素有抑制作用,其中L-甲硫氨酸、L-亮氨酸、L-赖氨酸适宜浓度可明显降低供试病原菌毒素对烟草的致病性,与对照差异极显著,其有效浓度分别为0．02mg／ml、0．02mg／ml、0．02～2mg／ml。     

β-Glucosidase from the cellulolytic system of Alternaria alternata autolyzed cultures

Abstract A β-glucosidase from centrifugated autolyzed cultures of Alternaria alternata has been purified 71 times by Sephadex G-200, CM-Biogel A and DEAE-Biogel A successively. The enzyme is a glycoprotein with 16% sugar and a M _r of 160 000, formed by two subunits of 60 000 and 80 000. The enzyme has optimum pH of 5 units and optimum reaction temperature of 50°C, being stable in a pH range of 3–8 and 0 to 60°C. The enzyme hydrolyzes different substrates showing maximum affinity and maximum hydrolysis velocity on cellobiose. The β-glucosidase is inhibited by gluconolactone but not by 10 mM glucose.     

紫茎泽兰入侵对土壤酶活性和理化因子的影响

紫茎泽兰是我国危害最严重的外来入侵植物之一,为探明其入侵对土壤肥力的影响,比较研究了紫茎泽兰、云南菅、狗尾草群落和撂荒地下0~30 cm的4层土壤中6种酶活性和12种理化因子。结果表明群落类型和土壤深度对测定的各参数均有显著影响。随土壤深度的增加,多酚氧化酶、碱性磷酸酶、脲酶活性,以及有机质、全氮、全磷、全钙、水解氮、有效磷、速效钾含量和pH值均降低。总的看来,紫茎泽兰群落下碱性磷酸酶和脲酶活性,有机质、全氮、全磷、全钙、水解氮和有效磷含量,以及pH值均较高,全钾含量较低,但速效钾含量并不低,表明紫茎泽兰入侵多年后土壤肥力水平提高,形成了对其生长有利的土壤环境。     

外来入侵种--紫茎泽兰花芽分化和胚胎学研究

应用石蜡切片法对紫茎泽兰(Eupatorium adenophorum)从花芽分化到胚胎形成的全过程进行系统观察,结果表明:紫茎泽兰从刚孕花序至头状花序的直径(d)大小为1.6～1.8 mm时为花芽分化期;d在1.8～2.0和3.8～4.0 mm范围内为大小孢子及雌雄配子体发育期,其中d在2.3～3.5 mm之间时为减数分裂的主要过程;药壁分化过程为双子叶型,胞质分裂为同时型,绒毡层发育属腺质绒毡层,成熟花粉粒为3-细胞型;胚囊发育属蓼形,胚珠倒生,单珠被,薄珠心;胚胎发育过程中有双胚现象.     

用超微细胞化学定位技术揭示ATP酶在紫茎泽兰高温适应性中的作用

【背景】外来人侵植物紫茎泽兰自然演化出耐高温种群,其适应机制与各种生理代谢有关。【方法】本文从超微细胞化学水平,对紫茎泽兰抗高温种群、敏感种群ATP酶活性定位,明确其在高温适应性中的作用,试图阐明该草的生态适应机制。【结果】正常情况下,紫茎泽兰ATP酶主要定位于细胞壁及细胞间隙周围的细胞壁表面;经40℃高温处理后,在不同的处理时间下,抗性、敏感种群之间ATP酶的活性表现出明显差异,其中以处理12h时差异最大,具体表现为抗高温种群的ATP酶活性明显高于敏感种群,ATP酶的定位点除细胞壁外,在细胞膜上也呈现大量的分布,而敏感种群在处理12h时的酶活性明显降低,只在细胞壁上有零星的分布。处理24h时,敏感种群叶片已完全萎蔫,细胞结构毁坏,细胞膜破损;而抗高温种群叶片仍然完好,细胞膜上仍有ATP酶分布。【结论与意义】经40℃高温处理后,紫茎泽兰抗高温种群ATP酶活性明显高于敏感种群,初步认为紫茎泽兰对高温的适应性与ATP酶活性相关。本研究为进一步阐明与紫茎泽兰适应性相关的入侵机理提供了资料。     

紫茎泽兰提取物对美洲大蠊和米蛾的忌避活性

应用“Y”型嗅觉仪和培养皿用紫茎泽兰(Eupatorium adenophorum Spreng)提取物对美洲大蠊Periplaneta americana(L.)和米蛾Corcyra cephalonica(Stainton)的忌避效果进行生物测定。结果表明,紫茎泽兰精油0·028g/L剂量对美洲大蠊忌避活性最高,平均忌避活力为78·28%,显著高于粗提物各剂量的忌避活力,而对米蛾幼虫生物测定的结果表明,10g/kg粗提物的剂量对其忌避效果最好,平均忌避活力为80·86%。     

紫茎泽兰生长发育过程中糖、激素、单宁、黄酮的变化

采用高效液相和分光光度法对紫茎泽兰不同发育阶段（种子,芽,幼苗和成株）糖、激素、单宁及总黄酮含量差异进行了研究。结果表明：不同糖类的变化。紫茎泽兰的葡萄糖含量以芽最高,为6.93%;而种子（0.16%）、幼苗（1.27%）、成株(1.07%)均明显低于芽阶段;同样,紫茎泽兰中蔗糖含量芽较高,为2.68%,而种子（0.32%）、幼苗（0.52%）、成株(0.09%)均明显低于芽阶段。果糖含量的变化,最大值也是在芽阶段（3.28%）,其次为种子阶段（2.56%）,而种子和成株阶段均很低（0.14%和0.55%）。测定中,海藻糖、棉子糖、甘露糖的含量差别很大,仅种子阶段测定出3种糖的含量,结果表明差别不大,依次为0.04%、0.04%、0.03%。激素类的变化。在不同发育阶段,紫茎泽兰芽阶段吲哚乙酸（IAA）含量较高,达到14.20μg·g^-1 Dw ,比种子阶段高1.25μg·g^-1 Dw,是幼苗的1.63倍,成株阶段的5.55倍。紫茎泽兰赤霉素（GA）含量在不同发育阶段存在着明显的差异,而且种子的GA含量（901.11μg·g^-1 Dw）明显高于芽、幼苗和成株阶段,而以芽和幼苗阶段含量最低,分别为97.35和84.29μg·g^-1 Dw,成株阶段略高于芽和幼苗阶段,为280.50μg·g^-1 Dw。单宁类的变化：紫茎泽兰单宁变化差异明显,紫茎泽兰种子中单宁含量为1.98%,明显高于芽、幼苗和成株阶段（<0.30%）;总黄酮类的变化：紫茎泽兰总黄酮含量在发育过程中呈不断上升趋势。紫茎泽兰种子中总黄酮含量很微弱,为0.04%,而芽、幼苗和成株阶段的紫茎泽兰总黄酮含量均明显高于种子阶段,并且这3个阶段之间含量差别不大,分别为（0.60%、0.64%、0.62%）。这些结果说明,糖、激素、单宁及总黄酮含量与植物生长发育的基本规律和代谢过程的调控密切相关。     

贵州水银洞金矿紫茎泽兰重金属元素测定与分析

利用原子吸收法对贵州水银洞金矿紫茎泽兰及其基质中Cr、Pb、Zn、Cd、Hg和As含量进行了测定和分析。结果表明,贵州水银洞金矿废水处理区土壤Hg(12.575 mg·kg^-1)和As(501.374 mg·kg^-1)已严重超标,Hg和As的平均含量分别是国家土壤环境质量三级标准(GB15618-1995)的8.383倍和12.534倍,污染极为严重;紫茎泽兰对该矿区不同的重金属富集能力不同,尤其对该矿区Cr有较强的富集作用,具有一定的Cr污染修复潜力。紫茎泽兰对所测定的6种重金属元素的吸收转移能力有较大的差异,整个植株对Pb、Zn 和Cr具有很强的吸收转移能力。其茎、叶对不同的重金属元素的吸收转移能力也呈现出很大的差异,紫茎泽兰茎对Cr、Pb和Cd具有很强的吸收转移能力,而叶对Zn、Pb和Hg具有很强的吸收转移能力。除As外,紫茎泽兰对Cr、Pb、Zn、Cd和Hg都具有不同程度的耐受能力,对该矿区的生态恢复具有重要的作用。     

In vitro efficacy of some fungicides on mycelial growth of Alternaria alternata and Mucor pyriformis

Various chemical fungicides, systemic and non-systemic, were tested against fruit rot pathogens viz. Alternaria alternata and Mucor pyriformis for the evaluation of inhibition of mycelial growth. In A. alternata, among the systemic fungicides used, hexaconozole showed highest inhibition of mycelial growth followed by carbendazim and least effective was myclobutanil. While in M. pyriformis, hexaconozole showed highest inhibition and least effective was bitertanol. Among the non-systemic fungicides tested in both A. alternata and M. pyriformis, mancozeb showed highest inhibition of mycelial growth followed by capton and the least inhibition was shown by zineb.     

The rhabditid nematode Phasmarhabditis hermaphrodita as a potential biological control agent for slugs

A nematode, Phasmarhabditis hermaphrodita, known to be associated with slugs but not previously thought to be parasitic, was shown to be a parasite capable of killing the pest slug Deroceras reticulatum. The parasite infects slugs in the area beneath the mantle surrounding the shell, causing a disease with characteristic symptoms, particularly swelling of the mantle. Infection leads to death of the slug, usually between seven and 21 days afterwards. The nematode then spreads and multiplies in the cadaver. In an experiment where individual D. reticulatum were exposed to different numbers of P. hermaphrodita, a significant positive relationship was found between nematode dose and slug mortality. In two experiments on host range, the nematode was found to infect and kill all pest slug species tested: Deroceras caruanae, Arion distinctus, Arion silvaticus, Arion intermedius, Arion ater, Tandonia sowerbyi and T. budapestensis, in addition to D. reticulatum.     

Effect of environmental factors on tenuazonic acid production by Alternaria alternata on soybean-based media

Aims: To determine the effects of water activity (a_W; 0·995–0·90), temperature (5, 18, 25 and 30°C), time of incubation (7–35 days) and their interactions on tenuazonic acid (TA) production on 2% soybean‐based agar by two Alternaria alternata strains isolated from soybean in Argentina. Methods and Results: TA production by two isolates of A. alternata was examined under interacting conditions of a_W, temperature and time of incubation on 2% soybean‐based agar. Maximum TA production was obtained for both strains at 0·98 a_W, but at 30 and 25°C for the strains for RC 21and RC 39, respectively. The toxin concentration varied considerably depending on a_W, temperature, incubation time and strain interactions. TA was produced over the temperature range from 5 to 30°C and a_W range from 0·92 to 0·995, however at 5 and 18°C little TA was produced at a_W below 0·94. Contour maps were developed from these data to identify areas where conditions indicate a significant risk for TA accumulation. Conclusions: The optimum and marginal conditions for TA production by A. alternata on soybean‐based agar were identified. The results indicated that TA production by A. alternata is favoured by different temperatures in different strains. Significance and Impact of the Study: Data obtained provide very useful information for predicting the possible risk factors for TA contamination of soybean as the a_W and temperature range used in this study simulate those occurring during grain ripening. The knowledge of TA production under marginal or sub‐optimal temperature and a_W conditions for growth are relevant as improper storage conditions accompanied by elevated temperature and moisture content in the grain can favour further mycotoxin production and lead to reduction in grain quality.     

Postharvest biocontrol of Alternaria alternata in Chinese winter jujube by Rhodosporidium paludigenum

Aims:  This study was conducted to measure the efficacy of the marine antagonist Rhodosporidium paludigenum in the suppression of postharvest decay of Chinese winter jujube caused by Alternaria alternata and to explore the possible mode of action involved.
Methods and Results:  The efficacy of controlling postharvest diseases by R. paludigenum was examined. Rapid yeast colonization of wounds was observed during the first 48 h at 25°C. The yeast at 1 × 10⁸ cells ml⁻¹ of washed cells suspension provided better control of A. alternata than any other treatment. The concentration of the antagonist had significant effects on biocontrol effectiveness: as the concentration of R. paludigenum was increased, the disease incidence decreased. Meanwhile, R. paludigenum significantly inhibited the natural development of decay and did not damage fruit quality parameters including lightness values, hue angle, firmness, soluble solids, ascorbic acid and titratable acidity in 21 days' storage at 25°C.
Conclusions:  Rhodosporidium paludigenum was effective in controlling postharvest decay of Chinese winter jujube and did not impair fruit quality parameters.
Significance and Impact of the Study:  Rhodosporidium paludigenum can be used as a nonchemical agent in postharvest biological control of Chinese winter jujube.     

紫茎泽兰9-羰基-10,11-去氢泽兰酮分布积累动态

9-羰基-10,11-去氢泽兰酮为紫茎泽兰（Eupatorium adenophorum）的主要致肝脏毒性成分及杀虫的生物活性成分。从紫茎泽兰叶片中分离提纯得到9-羰基-10,11-去氢泽兰酮（Euptox A）标准品,建立了高效液相色谱法测定紫茎泽兰中Euptox A含量的分析方法。采用C18反相色谱柱,柱温30°C,以甲醇-水（60：40,v/v）为流动相、流速为0.8 mL.min–1、检测波长为255 nm进行测定。Euptox A在紫茎泽兰中的添加回收率为97.3%–103.7%,检测限为0.4μg.g–1。利用建立的方法测定Euptox A在紫茎泽兰体内分布与积累的动态变化规律。结果表明,Euptox A主要分布在紫茎泽兰的叶片中,且在营养生长期积累量高,生殖生长期积累量低。该方法快速、简捷,可用于紫茎泽兰原料及其产品中Euptox A成分的测定。     

Fungitoxic activity of fruit extracts of Syzygium cumini (L.) Skeels against plant pathogenic fungi Alternaria alternata and Fusarium oxysporum

This study was aimed to evaluate the effectiveness of the aqueous and ethanolic extracts of fruits of Syzygium cumini, against the mycelial growth of Alternaria alternata and Fusarium oxysporum. The results showed that ethanolic extract at the concentrations of 7.5 and 9?mg/ml completely inhibited the mycelial growth of A. alternata and F. oxysporum, respectively. While the aqueous extract at a highest tested concentration (37.5?mg/ml) exhibited only 27.86 and 37.23% inhibition of mycelial growth of A. alternata and F. oxysporum, respectively. The spore germination assay also showed the complete inhibition of spore germination of A. alternata and F. oxysporum by ethanolic extract at 50 and 60?mg/ml concentrations, respectively. Minimum inhibitory concentration was recorded as 0.039 and 0.156?mg/ml in ethanolic extract and 20 and 6.25?mg/ml in aqueous extract against A. alternata and F. oxysporum, respectively. Phytochemical analysis also showed the presence of high amount of phenolics, tannins, flavonoids, alkaloids and saponins.