Fungitoxic activity of four thio-functionalised glucosinolate enzyme-derived products on ten soil-borne pathogens

Enzyme-derived products obtained from thio-functionalised glucosinolates showed high fungitoxicity, a wide activity spectrum and special physicochemical properties, which suggest their potential as alternatives to commercial fumigants for controlling several soil-borne pathogens. © 1999 Society of Chemical Industry     

Studies on the material resistance and moisture dynamics of Common juniper,English yew,Black cherry,and Rowan

The overall aim of this study was to provide comprehensive durability characteristics of wood species underutilized but frequently occurring in Central and Northern Europe: Common juniper (Juniperus communis L.), Black cherry (Prunus serotina Ehrh.), English yew (Taxus baccata L.), and Rowan (Sorbus aucuparia L.). Decay resistance was tested against white and brown rot causing basidiomycetes and soft rot causing micro-fungi in terrestrial microcosms. Their wetting ability was determined in terms of capillary water uptake at the end-grain, the liquid water uptake during submersion, the water vapor uptake at high humidity, and the water release during drying. All tests were performed with unleached and leached specimens. Durability classes were assigned based on results from the different tests. Juniper and Yew were classified very durable (Durability class DC 1); Black cherry and Rowan were found to be less durable (DC 3–5). Leaching did not affect the durability classification significantly. Durability characteristics were completed with different indicators for the wetting ability of the four wood species. The combined effect of wetting ability and inherent decay resistance was considered for service life modeling based on a resistance model using dose–response relationships between material climate (dose) and fungal decay above ground (response).     

短期玉米秸秆还田对冷凉地区土壤真菌多样性的影响

在玉米吐丝期,利用传统涂布平板法和高通量测序技术,设置常规秸秆不还田(CK)、秸秆深翻还田(SF)和秸秆旋耕还田(XG)3个处理,研究0~10 cm、10~20 cm和20~30 cm土层真菌群落丰富度、多样性和群落结构变化,揭示冷凉地区玉米秸秆还田真菌群落结构及其差异。结果表明:冷凉地区玉米秸秆还田对土壤真菌多样性的影响较大,秸秆还田土壤中可培养真菌数为SFXGCK;秸秆还田后土壤真菌优势菌群发生变化,CK优势菌为马拉色氏霉菌属、被孢霉属和葡萄孢属,XG优势菌为被孢霉属;XG和SF表层土壤中耐冷酵母菌属和被孢霉属是优势菌;SF处理20~30 cm土层优势菌为葡萄孢属。真菌菌群Alpha多样性、群落组成丰度、RDA(Redundancy analysis)和菌群相似性综合分析可知,SF和XG 0~20 cm土层菌群差异小;SF和XG均能增加10~30 cm土层真菌群落丰度。     

Using image analysis for quantitative assessment of needle bladder rust disease of Norway spruce

High elevation spruce forests of the European Alps are frequently infected by the needle rust Chrysomyxa rhododendri, a pathogen causing remarkable defoliation, reduced tree growth and limited rejuvenation. Exact quantification of the disease severity on different spatial scales is crucial for monitoring, management and resistance breeding activities. Based on the distinct yellow discolouration of attacked needles, it was investigated whether image analysis of digital photographs can be used to quantify disease severity and to improve phenotyping compared to conventional assessment in terms of time, effort and application range. The developed protocol for preprocessing and analysis of digital RGB images enabled identification of disease symptoms and healthy needle areas on images obtained in ground surveys (total number of analysed images n = 62) and by the use of a semiprofessional quadcopter (n = 13). Obtained disease severities correlated linearly with results obtained by manual counting of healthy and diseased needles for all approaches, including images of individual branches with natural background (R² = 0.87) and with black background (R² = 0.95), juvenile plants (R² = 0.94), and top views and side views of entire tree crowns of adult trees (R² = 0.98 and 0.88, respectively). Results underline that a well‐defined signal related to needle bladder rust symptoms of Norway spruce can be extracted from images recorded by standard digital cameras and using drones. The presented protocol enables precise and time‐efficient quantification of disease symptoms caused by C. rhododendri and provides several advantages compared to conventional assessment by manual counting or visual estimations.     

四硫代碳酸钠对蔬菜根病的防治效果及对土壤生物学性状的影响

为明确四硫代碳酸钠(sodium tetrathiocarbonate,STTC)在蔬菜根病防治上的应用价值及制定应用技术,本研究通过室内瓶土熏蒸法,进行了STTC对病菌的室内毒力测定;用温室盆栽法,进行植前熏蒸处理,测定土壤中病菌数量的变化和对病害的防效,同时进行植后熏蒸处理,测定药剂处理点和根际处病菌数量的变化;通过土壤施药后随即移栽幼苗的方法,评价药剂对蔬菜幼苗的安全性;通过室内模拟田间熏蒸条件,测定药剂不同浓度和熏蒸时间对土壤中主要微生物类群数量和主要土壤酶活性的影响。结果显示STTC对辣椒疫霉病菌Phytophthora capsici、黄瓜枯萎病菌Fusarium oxysporumf.sp.cucumerinum、茄子黄萎病菌Verticillium dahliae、番茄立枯病菌Rhizoctonia solani和蔬菜菌核病菌Sclerotinia sclerotiorum均有较好的杀灭活性,LD50分别为3.956、4.241、5.222、5.457和6.197mg/kg;80g/m2 STTC移植前处理对辣椒疫霉病和黄瓜枯萎病的防效可分别达到91.01%和82.51%;浓度低于900μg/mL的STTC对当日熏蒸后移栽的3叶期辣椒、黄瓜、番茄、白菜和油菜幼苗均表现安全;在辣椒和黄瓜生长期穴施1 200μg/mL STTC能有效减少土壤中辣椒疫霉病菌和黄瓜枯萎病菌的数量;土壤中微生物类群数量监测结果表明,在0.1~50.0μg/g浓度范围内,STTC对土壤真菌有强烈抑制作用,对土壤细菌和放线菌为先抑制后促进。对土壤酶活性测定结果表明,当STTC用量为0.1、1.0、5.0、10.0和50.0μg/g时,对土壤脲酶和蔗糖酶的活性表现为先抑制后促进,对蛋白酶的活性表现为在STTC低浓度时活性增加,高浓度时为先抑制后增加。综合结果表明,STTC用于经济作物生产中的土壤熏蒸具有安全、有效和施用简便的特点,或可广泛使用。     

Hide and seek – Infection rates and alkaloid concentrations of Epichloë festucae var. lolii in Lolium perenne along a land‐use gradient in Germany

The common forage grass Lolium perenne has evolved with the systemic fungal endophyte Epichloë festucae var. lolii. The endophyte provides herbivore resistance to the grass due to defensive alkaloids, some of which are toxic to grazing livestock. In this field study, we determine whether distribution of the endophyte‐grass association changes along a land‐use intensity gradient on 87 managed grasslands in three German regions. Endophyte infections were detected in 66% of the studied sites and infection rates within infected sites ranged from 1% to 95%. Alkaloid concentrations of lolitrem B (vertebrate toxin) exceeded the toxicity thresholds in 50 (14%) of 351 infected plants and of peramine (invertebrate deterrent/toxin) in 12 (3%) of 351 plants. Infection rates and alkaloid concentrations were not significantly affected by land‐use intensity and region, but alkaloid concentrations were higher in summer compared to spring. We conclude that risks for livestock intoxication are currently low, as (i) average alkaloid concentrations per grassland were always below toxicity thresholds and as (ii) none of the grasslands was dominated by L. perenne. We suggest avoidance of grass monocultures in Europe to keep intoxication risks for livestock low; we also recommend regular examination of seeds and grasslands, as seed producers might accidentally distribute infected seeds, and as climate warming might further enhance the distribution of Epichloë endophytes in European grasslands.     

Potential Pharmacological Resources: Natural Bioactive Compounds from Marine-Derived Fungi

In recent years, a considerable number of structurally unique metabolites with biological and pharmacological activities have been isolated from the marine-derived fungi, such as polyketides, alkaloids, peptides, lactones, terpenoids and steroids. Some of these compounds have anticancer, antibacterial, antifungal, antiviral, anti-inflammatory, antioxidant, antibiotic and cytotoxic properties. This review partially summarizes the new bioactive compounds from marine-derived fungi with classification according to the sources of fungi and their biological activities. Those fungi found from 2014 to the present are discussed.     

干旱胁迫下外源内生菌提取物AAC-2对玉米苗期生理生化特性的影响

以植物内生菌提取物(AAC-2)拌种预处理玉米(Zea mays L.)种子,在10%PEG-6000胁迫模拟干旱环境下,研究植物内生菌提取物AAC-2对玉米幼苗生理生化特性的影响。结果表明,经AAC-2处理后玉米苗期叶片比对照叶绿素含量增加3.33%,脯氨酸含量增加10.43%,可溶性糖含量增加11.29%,丙二醛含量降低18.50%。植物内生菌提取物(AAC-2)通过对玉米苗期生理生化特性的干旱适应性调节,可有效缓解干旱胁迫对玉米幼苗的伤害,提高其抗旱能力。     

真菌固态载体预处理对不灭菌玉米秸秆降解的影响

采用云芝变色栓菌(Trametes versicolor)、色精木霉菌(Trichoderma chromospermum)、深绿木霉菌(Trichoderma atroviride)和云芝变色栓菌分别与色精木霉菌、深绿木霉菌的混合菌对干黄玉米秸秆进行真菌预处理。结果显示,真菌预处理不灭菌秸秆30 d后,木质纤维素的降解率几乎可以忽略,在不灭菌的环境中,接入的真菌对秸秆本身附着的微生物群落不能形成竞争优势,造成较低的木质素降解率。而云芝变色栓菌、色精木霉菌、深绿木霉菌以及云芝变色栓菌分别与色精木霉菌、深绿木霉菌的混合菌对灭菌秸秆预处理30 d后,木质素的降解率分别为34.0%、38.1%、38.1%、39.1%及40.3%。为降低秸秆的灭菌成本,将真菌预处理30 d后的灭菌秸秆作为真菌固态载体与不灭菌秸秆按照1∶9、1∶4及1∶1的干质量比混合培养30 d,结果显示,采用云芝变色栓菌分别与色精木霉菌和深绿木霉菌的混合菌固态载体预处理不灭菌秸秆,木质素降解率可达到30%~40%。因而,真菌固态载体可以较好地适应非灭菌环境并对秸秆中的木质素进行有效降解,是一种有效降低过程成本的预处理手段。