冬青卫矛上的叶点霉属新种

报道了分离自冬青卫矛植物叶片上的一株内生真菌。在培养基上产生分生孢子器,分生孢子具有一明显的附属物,根据形态特征鉴定为新种,命名为冬青卫矛叶点霉Phyllosticta euonymi-japonici。模式标本(IBE 0000989)保存于大连民族学院生物资源与环境研究所标本室。     

Culture age impacts Plectosporium alismatis propagule yields and subsequent desiccation and UV-radiation tolerance

The effect of culture age on yields, desiccation tolerance and resistance to ultraviolet radiation of Plectosporium alismatis, a potential mycoherbistat of aquatic weeds in Australian rice fields, was studied. P. alismatis was grown in a liquid basal medium supplemented with malt extract and sodium nitrate and harvested after 7, 14 or 21 days incubation. Although chlamydospore yields harvested from 14-day-old liquid cultures were significantly higher (29.2×10⁵ chlamydospores mL^?1) than chlamydospore yields harvested from 7-day-old liquid cultures (1.07×10⁵ chlamydospores mL^?1) or from 21-day-old liquid cultures, the germination of freshly-harvested chlamydospores from 7-day-old cultures (72.7%) was significantly reduced when propagules were grown for 14 days (55.3%). When exposed to UV-radiation, conidia and chlamydospores harvested from 14-day-old cultures germinated at a lower rate (<20%) than conidia and chlamydospores harvested from 7-day-old cultures (>40%). When conidia and chlamydospores were dried and subsequently exposed to UV, less than 30% of propagules harvested from 7-day-old cultures germinated, whereas less than 10% of propagules harvested from 14-day-old cultures germinated. A three-way analysis of variance including culture age, UV exposure and type of propagules confirmed that the culture age had more impact on the germination of fresh or dry propagules (P=0.00001 and P=0.0004, respectively) than the type of propagules considered (P=0.5). These results demonstrate that the culture age impacts significantly propagule yields and germination of P. alismatis conidia and chlamydospores, particularly after stress caused by dehydration and/or exposure to UV-B radiation.     

影响稻恶苗菌分生孢子萌芽管融合的环境因子研究

本文报导温度、光照、几种营养物质和pH值对稻恶苗菌[Gibberella fujikuroi(sacc.)wr.]分生孢子萌芽管融合频率的影响。试验结果证明温度为28℃,光照为完全黑暗下,pH值为中性偏碱性的PD培养液中,稻恶苗菌分生孢子萌芽管融合频率最高。     

Survival of Neozygites cf. floridana (Zygomycetes: Entomophthorales) in mummified cassava green mites and the viability of its primary conidia

The survival of Neozygites cf. floridana (Weiser and Muma) as dry hyphal bodies in mummified cassava green mites, Mononychellus tanajoa (Bondar), at 5.0% RH in the dark was affected by storage temperature. Survival of the fungus in mummies kept at 24±1.0°C could be demonstrated for 6–7 months. When stored at 4°C, the fungus sporulated from 90% of the mummies liberating an average of 186.9 primary conidia per mummy even after a storage period of 16 months, when the experiment was terminated. The temperature, humidity and light condition significantly affected the viability of primary conidia. The percent viability across all factors dropped from 98.4% after 0 h (beginning of the experiment) to 23.4% after a 1 h exposure to the conditions tested. Lower temperatures maintained higher viabilities with 86.3% of the conidia surviving after 18 h at 18°C, whereas almost all conidia died after 12 h at 33°C. Conidia survived less than 1 h when exposed to SDs (saturation deficit) of 2.0 mm Hg or higher at any tested temperature.     

Effects of fungicides on the growth and conidial germination of Colletotrichum coccodes and on the development of black dot disease of potatoes

The effects of 10 fungicides on the growth of Colletotrichum coccodes in agar culture and on the germination of conidia was investigated. In field experiments in 1990 and 1991 the extent to which treating black dot-affected potato seed tubers with fungicides affected the development of the disease on stem bases, roots and tubers was assessed. Black dot was also assessed on plants from field trials in 1990 which were designed to investigate the efficacy of the soil sterilant 1,3-dichloropropene (Telone) and two nematicides, aldicarb (Temik) and ethoprophos (Mocap). Prochloraz and fenpiclonil were the most effective fungicides in decreasing the size of C. coccodes colonies on agar. Imazalil, propiconazole and dichlorophen were also effective, but at higher concentrations, whereas tolclofos-methyl, thiabendazole and benomyl were only moderately effective. Resistant sectors developed from inhibited colonies on agar containing fenpiclonil and tolclofos-methyl. Conidial germination was prevented at 1 mg/litre fenpiclonil and 5 mg/ litre dichlorophen; imazalil, benomyl and thiabendazole were also moderately effective. Fenpiclonil and propiconazole seed tuber treatments consistently decreased black dot infection on roots, stem bases and daughter tubers early in the season, but only fenpiclonil decreased disease on tubers at harvest in October. Propiconazole also delayed emergence and decreased stem numbers. Soil treatment with 1,3-dichloropropene, aldicarb or ethoprophos had no effect on black dot but Rhizoctonia solani tuber infection and black scurf were increased.     

暹罗炭疽菌同源异型盒转录因子CsHtf1的生物学功能

【背景】暹罗炭疽菌(Colletotrichum siamense)是橡胶炭疽病害的主要致病菌,严重制约着天然橡胶产量。在植物致病真菌中广泛存在同源异型盒转录因子,其参与调控真菌无性生殖、侵染和代谢等诸多方面。【目的】明确在暹罗炭疽菌中鉴定的一个同源异型盒转录因子CsHtf1的生物学功能。【方法】利用同源重组的方法获得Cshtf1基因的敲除突变株,并对其营养生长、孢子产生和致病性等表型进行分析。【结果】Cshtf1基因编码600个氨基酸且含有1个HOX结构域;与野生型相比,Cshtf1敲除突变株营养生长和致病性无显著差异,而突变株分生孢子产量显著降低且黑色素产量增加。【结论】CsHtf1参与调控暹罗炭疽菌的分生孢子及黑色素产生。     

Histopathology of Nomuraea rileyi in larvae of Heliothis zea and in vitro enzymatic activity

Conidia of Nomuraea rileyi germinated in 2 days on larvae of Heliothis zea. Germ tubes penetrated the cuticle directly. This seemed to be aided by enzymatic secretions as evidenced by the darkening of the epicuticle and part of the exocuticle suggesting apparent lysis. In the endocuticle, hyphae grew parallel to the endocuticular laminae with lateral branches penetrating into epidermis and then hemocoel where they proliferated and attacked internal organs. Blood cells were first to be invaded, followed by fat lobes, Malpighian tubules, muscles, and mesenteron. Disintegration of body tissues of the host began before death. At death, hyphae began to grow outward. In vitro enzymatic tests showed that N. rileyi secretes chitinase, protease, and lipase.     

Regularities in the Germination of Conidia of Phytopathogenic Fungi

The autoregulation of conidium germination in phytopathogenic micromycetes of the genera Fusarium, Botrytis, and Bipolaris was studied. It was shown that Trichoderma longibrachiatum was less competitive than Fusarium oxysporum after their simultaneous inoculation but inhibited the phytopathogen growth in the case of earlier introduction. In the latter case, no autoinhibition of the germination of F. oxysporum conidia occurred; moreover, a cooperative effect was observed, i.e., the number of germinated F. oxysporum conidia increased with an increase in their density.     

Effects of nutrients on germination of Verticillium lecanii (=Lecanicillium sp.) conidia and infection of greenhouse whitefly, (Trialeurodes vaporariorum)

Laboratory experiments were conducted to assess effects of nutrients on germination of Verticillium lecanii (=Lecanicillium sp.) conidia and infection of the greenhouse whitefly, Trialeurodes vaporariorum. Suspensions of V. lecanii conidia were prepared in four nutrient solutions: 2% glucose, 2% sucrose, 2% maltose, and 2% peptone. Suspensions in de-mineralized water served as the control. At 23°C the germination rate was highest in the 2% glucose solution, followed by sucrose, maltose, demineralized water, and peptone, respectively. Germ tube growth was greatest at 23°C in the 2% glucose solution after 10 h incubation. Results of the bioassays indicated that the nutrients influenced whitefly infection. Infection levels were highest for conidial suspensions (1×10⁶ conidia/mL) prepared in 2% glucose, and were significantly greater than for peptone, demineralized water and maltose. Infection levels at 1×10⁸ conidia/mL were not significantly different from each other for all materials tested. The potential use of nutrients in a spray formulation as a means of enhancing field efficacy are discussed.     

四霉素对稻瘟病菌丝和孢子生长的影响

进行了四霉素对稻瘟病菌作用机理的研究,结果表明,四霉素对稻瘟病菌菌丝生长及孢子萌发具有较强的抑制作用。四霉素处理后菌丝发生扭曲变形,粗细不一,部分菌丝内含物流出,出现空管,而正常菌丝粗细较均匀一致,原生质和核等内含物分布均匀;正常的稻瘟病菌分生孢子有明显的隔膜,产孢量较大,而四霉素处理后分生孢子隔膜模糊不清,且在边缘出现泡状突起,产孢较少。通过遗传稳定性初步试验,明确了四霉素对稻瘟病菌具有抑制作用而无杀死作用。