Buchbesprechung

Sacharenko, A. W.: Theoretisehe Grundlagen der Regulierung der Un‐krautkomponente von Agrophytozönosen in Ackerbausystemen (russ.). Verlag der Moskauer Landwirtschaftlichen Timirjasew ‐ Akademie Moskau. 2000, 466 S., 27 Abb., 122 Tab., ISBN 5–7230–0462‐X     

花青素对神经退行性疾病保护作用的研究进展

对近年来花青素在神经退行性疾病中的研究进展进行综述,并从抑制氧化应激、缓解神经炎症、缓解兴奋性毒性和抑制蛋白异常聚集等方面对花青素的神经保护作用机制进行探讨,为进一步了解和研究花青素类化合物在神经退行性疾病中的预防作用提供科学依据。     

Effect of temperature on antagonistic and biocontrol potential of shape Trichoderma sp. on Sclerotium rolfsii

Sclerotium rolfsii is a destructive soil-borne and postharvest plant pathogen. Use of the antagonistic fungus Trichoderma sp. has been earlier reported by us to successfully control this pathogen under postharvest conditions. In the present paper we report on the effects of temperature on the growth and biocontrol potential of Trichoderma sp. on S. rolfsii. Experimental results indicated that S. rolfsii and Trichoderma sp. have different temperature optima for growth: 30–35 °C for the pathogen and 25–30 °C for the antagonist. In dual culture, Trichoderma overgrew S. rolfsii at 25 °C and 30 °C, but at 35 °C and 37 °C, S. rolfsii overgrew the colony of Trichoderma. Trichoderma produced higher concentration of fungitoxic metabolites in broth culture at higher temperatures. In bioassays using ginger slices and whole rhizomes, it has been demonstrated that Trichoderma is not very effective in suppressing S. rolfsii at temperatures above 30 °C. In light of these results, possible mechanisms of biocontrol of S. rolfsii as a postharvest pathogen has been discussed. Storage temperature has been suggested as a critical factor in biocontrol of S. rolfsii. This revised version was published online in June 2006 with corrections to the Cover Date.     

Microbial consortium-mediated reprogramming of defence network in pea to enhance tolerance against Sclerotinia sclerotiorum

Aims: To evaluate the potentiality of three rhizosphere microorganisms in suppression of Sclerotinia rot in pea in consortia mode and their impact on host defence responses. Methods and Results: Pseudomonas aeruginosa PJHU15, Trichoderma harzianum TNHU27 and Bacillus subtilis BHHU100 from rhizospheric soils were selected based on compatibility, antagonistic and plant growth promotion activities. The microbes were used as consortia to assess their ability to trigger the phenylpropanoid and antioxidant activities and accumulation of proline, total phenol and pathogenesis‐related (PR) proteins in pea under the challenge of the soft‐rot pathogen Sclerotinia sclerotiorum. The triple‐microbe consortium and single‐microbe treatments showed 1·4–2·3 and 1·1–1·7‐fold increment in defence parameters, respectively, when compared to untreated challenged control. Activation of the phenylpropanoid pathway and accumulation of total phenolics were highest at 48 h, whereas accumulation of proline and PR proteins along with activities of the antioxidant enzymes was highest at 72 h. Conclusions: The compatible microbial consortia triggered defence responses in an enhanced level in pea than the microbes alone and provided better protection against Sclerotinia rot. Significance and Impact of the Study: Rhizosphere microbes in consortium can enhance protection in pea against the soft‐rot pathogen through augmented elicitation of host defence responses.     

Shelf-life enhancement of fresh ginger rhizomes at ambient temperatures by combination of gamma-irradiation, biocontrol and closed polyethylene bag storage

The feasibility of a combination process involving gamma-irradiation, packing in closed polyethylene bags and biological control of fungi causing storage rot was evaluated as a means of extending the shelf-life of fresh ginger rhizomes at ambient temperatures (25–30°C). Storage in closed polyethylene bags reduced weight loss but increased sprouting and rooting, which could be prevented by gamma irradiation to 60 Gy. Rotting caused by Sclerotium rolfsii was, however, a major cause of spoilage during extended storage.
Four isolates of Trichoderma sp. isolated from sclerotia of S. rolfsii infecting ginger rhizomes, one of Gliocfadium uirens, and four isolates of fluorescent Pseudomonas were tested, out of which, one isolate of Trichoderma was found to be highly effective in suppressing the growth of S. rolfsii. The efficacy of the antagonist was demonstrated under simulated market conditions using artificially inoculated rhizomes. The recommended procedure consists of dipping washed, air dried rhizomes in Trichoderma suspension (10⁸spores ml^-1), air-drying, packing in 250 gauge LDPE bags followed by irradiation to 60 Gy. Rhizomes thus treated remained in good marketable condition for up to 2 months at ambient temperature without sprouting or significant loss of quality and less than 5% weight loss.
An in vitro bioassay system was developed to demonstrate the efficacy of the antagonist to protect the cut surface of sliced rhizomes inoculated with the pathogen. The method could be used for rapid screening of antagonists.     

木霉菌在玉米病害生物防治中的作用机制及应用

目前,世界上共有分属于10个属（Trichoderma,Gliocladium,Chaetomium,Bacillus,Burkhoderia,Streptomyces and Pseudomonas,Pantoea,Enterobacter,Macrobacterium）中的微生物被试验用于玉米病害的生物防治,其中细菌14种,真菌17种,放线菌1种。国际上由木霉菌开发的生物杀菌剂和生物肥料有50余种,其中以哈茨木霉T22菌株开发的产品最为著名。目前在我国也开发出了4种木霉菌剂型（可湿性粉剂、颗粒剂、水分散粒剂和种衣剂）,正式登记的木霉菌杀菌剂有7种,其中6种为可湿粉剂,1种为水分散粒剂,主要登记用于防治番茄、观赏百合、黄瓜的立枯病、猝倒病、根腐病、灰霉病、霜霉病以及小麦的纹枯病,但尚无木霉菌生物农药被登记用于防治玉米病害。以木霉菌为主要成分登记的菌肥产品有11种,其中在玉米上应用的有2种。由课题组研制的木霉菌颗粒剂和种衣剂通过土壤穴施和种子包衣可有效防治玉米茎腐病和纹枯病,其中木霉菌颗粒剂防效达65%-87%。近期研制的木霉菌可湿性粉剂对玉米小斑病的防效达50%-60%。国际上已鉴定出多种可诱导玉米获得系统抗性的木霉菌源激发子,其中包括Sm1、纤维素酶、疏水蛋白和Avr4 /Avr9等效应因子。本课题组近年鉴定出Thc6（锌指蛋白类转录因子）、PAF-AH和Thph1/Thph2的编码产物在系统诱导以JA/ET信号调控的玉米抗弯孢菌叶斑病中具有重要作用,符合植物免疫MAMPs模式,为全面认识木霉菌诱导免疫机理提供了重要理论依据。木霉菌诱导玉米从根至叶片的防御反应系统传导机制还需深入研究。     

Antagonistic activity and hyphal interactions of Trichoderma spp. against Fusarium proliferatum and F. oxysporum in vitro

Trichoderma is a well-known antagonist against soilborne plant pathogens. However, the species and even various isolates have different biocontrol potential. To evaluate the antagonistic activities of Trichoderma harzianum, T. harzianum strain T100 (T100), T. viride and T. haematum against Fusarium oxysporum and F. proliferatum, we used dual culture and productions of volatile and non-volatile metabolites in three different phases in vitro. An analysis of the data in dual culture tests represented T. viride, T. haematum and T100 as effective antagonists of Fusarium while T100 was the only fungus being able to lyse the confronting mycelia. Similar results were obtained in the volatile metabolites tests also. In contrast with the two previous tests, the non-volatile metabolites produced by T. harzianum inhibited Fusarium mycelial growth the most, and T100 acted moderately. It was also clearly showed that the antagonistic effect of Trichoderma spp. was more on F. proliferatum than on F. oxysporum. Finally, because Trichoderma spp. was most effective in the second phase, we recommend to use T100 against F. proliferatum at the initial stages of infection as its mycoparasitism on F. oxysporum was observed microscopically through forming apressoria structures without any coiling around the pathogen.     

Density independent population dynamics by Trichoderma virens in soil and defined substrates

Classical models of population dynamics predict that with increasing initial population densities the per capita growth will diminish. Observations over a broad range of initial densities with a wild-type and a genetically engineered strain of the filamentous fungus, Trichoderma virens (Arx), in soil and autoclaved soil differed from these predictions. The per capita growth response of T. virens in vitro was found to be density dependent on potato dextrose agar, but density independent on water agar. Further experiments with a defined, carbon-free medium (Vogel's medium) and, with the same medium containing sucrose, indicated that density dependent per capita growth occurred in the nutrient-rich medium but not the oligotrophic medium. This hypothesis was tested and supported experimentally through observation of density dependent per capita growth after adding nutrients to autoclaved soil. Development of better models of population dynamics will be important to predict successfully the likelihood and extent of establishment after field release of microorganims.     

Seed biopriming with novel strain of Trichoderma harzianum for the control of toxigenic Fusarium verticillioides and fumonisins in maize

Fusarium verticillioides is one of the most important fungal pathogens in maize causing both pre- and post-harvest losses and also capable of producing Fumonisins. In the present study attempts have been made for screening potential T. harzianum from native rhizosphere and to study its effect on Fusarium ear rot disease, fumonisin accumulation in different maize cultivars grown in India. Eight isolates of T. harzianum were isolated and T. harzianum isolate Th-8 exhibited better antifungal activity than carbendizim. Th-8 was formulated in different solid substrates like wheat bran, paddy husk, talcum powder and cornstarch. Maize seeds of kanchan (moderately resistant), pioneer (resistant) and sweet corn (susceptible) were selected for laboratory and field studies and these seeds were treated with a conidial suspension of T. harzianum at the rate of 1 × 10⁸ spore/ml and formulation at the rate of 10 g/kg. Treated seeds were subjected to evaluate F. verticillioides incidence, seed germination, seedling vigour and field emergence, yield, thousand seed weight and fumonisin production. It was found that the pure culture of T. harzianum was more effective in reducing the F. verticillioides and fumonisin incidence followed by Talc formulation than the carbendizim treated and untreated control. Formulations of T. harzianum were effective at reducing the F. verticillioides and Fumonisin infection and also increasing the seed germination, vigour index, field emergence, yield, and thousand seed weight in comparison with the control.     

木霉菌防治植物真菌病害研究进展

木霉菌是一种重要的植物病害生防因子,尤其在防治植物病原真菌病害中一直受到极大的关注。木霉菌依靠其菌株在包括趋向生长、识别、接触、缠绕与穿透等步骤的真菌寄生过程中分泌产生的几丁质酶、葡聚糖酶、纤维素酶、蛋白酶等一系列细胞壁降解酶,进行重寄生作用,拮抗其他植物病原菌,行使其生防功能。我们简要概述了木霉菌的种类、拮抗对象、抑菌机制、诱导抗性、促生作用、基于分子生物学的转基因工程研究,以及木霉菌在植物病原真菌生物防治中的应用。