铝胁迫对酸性红壤中真菌种群多样性的影响

通过聚合酶链式反应-限制性片段长度多态(PCR-RFLP)技术构建了红壤真菌的内转录间隔区(Internal Transcribed Spacer,ITS)rDNAs文库,比较分析了红壤地区典型森林土和农田土真菌群落结构对铝胁迫的响应,构建了6个土壤样品的真菌ITS rDNAs文库。从这6个克隆文库中随机挑取克隆进行了PCR-RFLP指纹图谱分析,共获得77个独特的真菌操作分类单元(OperationalTaxanomicalUints,OTUs)。对77个OTUs的代表性克隆测序并利用Blast工具进行分析(相似性95%~100%)。研究结果表明森林土壤和农田土壤样品中真菌类群79.2%(61)属于子囊菌门(Ascomycota)、担子菌门(Basidiomycota)和球囊菌门(Glomeromycota),20.8%(16)属于未分类的簇(Unclassifiedfungi),其中担子菌门真菌在两种土壤中具有明显优势。物种多样性指数(Simpson、Shannon和Chao1)分析表明,铝胁迫降低了土壤真菌种群的多样性,农田土壤中真菌的种群多样性明显高于森林土壤。而且随着铝胁迫浓度的增加,担子菌门真菌在两种土壤中丰度明显下降,子囊菌门真菌的丰度显著上升,在高铝处理浓度处理的土壤中演变为优势种群。     

Plant pathogen protection by arbuscular mycorrhizas: A role for fungal diversity?

Arbuscular mycorrhizal (AM) fungi can confer protection to host plants against some root pathogens, and several mechanisms for these phenomena have been proposed. If AM fungal taxa vary in the ways that they limit the negative effects of pathogens on host plants, additive and/or synergistic interactions among members of diverse AM fungal assemblages and communities may result in a greater pathogen protection than is currently predicted. However, in a review of the literature on interactions between AM and pathogenic fungi, we found few examples that compared the effectiveness of single- and multi-species AM fungal assemblages. Here, we briefly recount the generally recognized mechanisms of pathogen protection by AM fungi and present evidence, where appropriate, for functional diversity among AM fungal taxa with regard to these mechanisms. We propose that functional complementarity of AM fungal taxa in interactions with pathogens could mimic, or even be the cause of, previously observed relationships between AM fungal diversity and plant productivity.     

Dealing with the variability in biofumigation efficacy through an epidemiological framework

Biofumigation, as originally defined, is the use, in agriculture, of the toxicity of Brassica crop residues to control soilborne plant pathogens. This toxicity is specifically attributed to the release of toxic isothiocyanates, through the hydrolysis of glucosinolates present in the crop residues. This technique is considered a possible alternative to the use of pesticides, but field studies have generated conflicting data concerning the efficacy of biofumigation at field scale, limiting the use of this technique. Analytical studies based on a systematic approach involving evaluation of the potential effects of isothiocyanates can be used to address this problem in a rigorous manner. However, many recent studies have indicated that the mechanisms underlying biofumigation are much more complex than a simple toxic effect of residues. In this review, we dissect and discuss the problems encountered when trying to understand the variability in biofumigation efficacy and propose an integrative epidemiological approach to overcome these problems. This approach involves separating the effects of the different parameters of the system, such as the effects of different management phases of the biofumigant crop (i.e. the period of biofumigant crop growth and the phase during which crop residues are pulverised and incorporated into the soil) on the epidemiological mechanisms driving the development of an epidemic (density of primary inoculum and dynamics of disease progression). Finally, we propose new avenues of research into biofumigation in which the use of epidemiological tools and methods may improve our understanding of the factors underlying variation in the efficacy of biofumigant crops.     

云南省荞麦叶枯病病原菌鉴定及其生物学特性

为明确云南省荞麦叶枯病病原菌种类,采用常规组织分离法获得病原菌菌株LW2015.3,通过形态学特征及分子生物学技术对菌株LW2015.3进行鉴定,并研究其生物学特性。结果表明,荞麦叶枯病病原菌的分生孢子呈倒棍棒状或倒梨状,褐色,具3～8个横隔膜,0～4个纵斜隔膜,大小为16.5～45.0μm×5.0～13.5μm,厚垣孢子呈球形,直径为6.0～12.0μm;该菌株ITS序列系统发育进化分析结果表明,菌株LW2015.3与链格孢Alternaria alternata(登录号:MG195995.1)的同源性为100%,结合形态学特征与分子鉴定结果确定云南省荞麦叶枯病病原菌为链格孢A. alternata(登录号:KT362732.1)。该病原菌菌丝生长适宜温度为20～30℃,25℃为最适温度;当p H为6～9时菌丝生长速率加快,pH 7最适菌丝生长;PDA培养基和PSA培养基最适菌丝生长;该病原菌对以麦芽糖为碳源和以硝酸钠为氮源时的利用率最高;菌丝的致死温度为50℃,10 min;不同光照条件对菌丝生长的影响有显著差异,连续光照最有利于菌丝生长。     

贵州省白及叶褐斑病病原菌鉴定及其生物学特性

为明确贵州省白及叶褐斑病病原菌及其生物学特性,采用组织分离法和离体接种法分别对其病原菌进行分离和致病性测定,利用形态学及ITS、EF-1α、β-tubulin基因序列分析对病原菌的分类进行鉴定,并对病原菌的生物学特性进行研究。结果表明:分离得到的白及叶褐斑病病原菌菌株编号为HGUP_(17)355;该菌菌丝白色、羊绒状,菌落中心隆起呈淡黄色、背面枫叶红色,大型分生孢子窄镰刀形,3～8个分隔,未见厚垣孢子,小型分生孢子卵圆形,1～2个分隔;在以ITS、EF-1α、β-tubulin三个基因序列构建的系统发育树中,菌株HGUP_(17)355与燕麦镰刀菌Fusarium avenaceum聚于一支,且支持率达100%,结合形态特征与分子生物学将其鉴定为燕麦镰刀菌。该菌菌丝最适生长温度为20℃,最适生长pH为6,在燕麦片琼脂培养基上生长最快,以麦芽糖为碳源、以L-苯丙氨酸为氮源时利用率最高,致死温度为45℃,对光照不敏感。     

西北地区马铃薯疮痂病病原菌鉴定及其生物学特性

为明确西北地区马铃薯疮痂病病原菌的种类和生物学特性,分别采用常规组织分离法和土壤混悬液分离法从宁夏、陕西和甘肃3个省区采集的29份疮痂病发病薯块和8份发病地块土壤中进行病原菌分离,并利用形态特征、生理生化特性和16S rDNA序列分析对病原菌进行鉴定。结果表明,从发病薯块和发病土壤中共分离到50株链霉菌Streptomyces spp.,通过回接法验证获得6株马铃薯疮痂病致病菌株。6株致病菌株的培养特性和形态特征差别较大;其中菌株G4-1、G9和SYN13不能以果糖和木糖为单一碳源,菌株SYNT3不能以棉子糖为单一碳源;除菌株NLG4-1外,其余5株菌株均能在络氨酸琼脂培养基上产生黑色素。经16S rDNA序列分析,菌株G4-1、G9与疮痂病链霉菌S. scabiei的相似率分别达99.47%和99.34%,菌株NLG4-1、SYNT3与S. enissocaesilis的相似率分别达97.90%和98.18%,菌株GBH2与加利利链霉菌S. galilaeus的相似率达99.93%,菌株SYN13与S. turgidiscabies的相似率达97.56%,表明西北地区马铃薯疮痂病病原菌至少存在4个种。     

杉木五种斑痣盘菌科病菌的识别及学名商榷

经过数年调查发现,安徽省境内的杉木上斑痣盘菌科病原菌共4属5种,它们是杉生小双梭孢盘菌Bifusella cunnighamiicola Korf & Ogimi,皮特拉克散斑壳Lophodermium petrakii Durrian,毁坏舟皮盘菌Ploioderma destruens Y.R.Lin et Hou,汉德尔舟皮盘菌P.handelii (Petrak) Y.R.Lin et Hou和杉木小鞋孢盘菌Soleella cunnighamiae Shao et Zinno.文中描述了各种菌的主要特征,并编制了种的检索表以资识别.对于长期以来杉木落针病病原鉴定中所存在的同物异名问题也进行了商榷.     

鸭传染性浆膜炎的病原分离鉴定与药防研究

本研究从四川、重庆等地鸭传染性浆膜炎鸭群中分离出可疑致病菌株19株,经生化鉴定为鸭疫里默氏菌,血清型鉴定除1株属Ⅱ型外,其余均为Ⅰ型;通过协同药物敏感性测定,研制出新型复方制剂“鸭浆灵”,经控制试验与临床应用效果显著。     

The Exploitation of Crop Allelopathy in Sustainable Agricultural Production

Crop allelopathy may be useful to minimize serious problems in the present agricultural production such as environmental pollution, unsafe products, human health concerns, depletion of crop diversity, soil sickness and reduction of crop productivity. Several crops including alfalfa, buckwheat, maize, rice, rye, sorghum, sunflower, wheat, etc. are affected either by their own toxicity or phytotoxin exudates when their residues decompose in the soil, that show strong suppression on weed emergences. Allelopathic crops when used as cover crop, mulch, smother crops, green manures, or grown in rotational sequences are helpful in reducing noxious weeds and plant pathogen, improve soil quality and crop yield. Those crop plants, particularly the legumes, incorporated at 1–2 tons ha⁻¹ (alfalfa, buckwheat, rice by-products), which can give weed reduction and increase of rice yield by 70 and 20 %, respectively, are suggested for use as natural herbicides. Allelochemicals from allelopathic crops may aid in the development of biological herbicides and pesticides. Cultivating a system with allelopathic crops plays an important role in the establishment of sustainable agriculture. The introduction of allelopathic traits from accessions with strong allelopathic potential to the target crops will enhance the efficacy of crop allelopathy in future agricultural production.     

Role of RGD-mediate Adhesion in Signal Transduction of Plant Resistance

During the period of the primary contact time,there are series of recognition between the Fungal pathogens and the plant cell,which include physical and biochemical recognition.The results affect the infection directly.In the process of penetrating plant cell walls,there is not only an emzymolysis to plant cell wall,but also a mechanical squeeze to the cell wall.The latter almost trigger cell-associated defense response,such as extracellular hydrogen peroxide generation and callose doposition The complete cell wall-related defence response will be induced by mechanical signal and chemical signal together.Being to with the mammalian cell,in plant cell wall intergrin-like proteins have response to perceive the mechanical signal,which is via RGD(Arg-Gly-Asp)motif,and the plasma membrane-cell wall adhesion is required for expression of plant defense responses during fungal penetration.