委内瑞拉链霉菌RL-2活性产物对植物病原真菌的抑制作用及其作用机制

为了探明委内瑞拉链霉菌RL-2在植物病害生物防治中的应用价值,在离体条件下采用生长速率法、活体条件下采用盆栽法研究了RL-2活性产物对多种植物病原真菌的抑制作用。结果表明:在离体条件下,RL-2活性产物对供试的7种病原真菌均有较强的抑制作用,其中对稻瘟病菌的抑制作用最强,EC50为5.35mg/L;在活体条件下,不仅能阻止专性寄生的黄瓜霜霉病病原菌菌丝入侵,而且对已侵入的菌丝有很好的治疗效果。电镜观察结果显示,RL-2活性产物强烈抑制病原菌菌丝生长和孢子萌发,引起菌丝膨大和畸形、孢子萌发率降低、萌发孢子芽管畸形。此外,经RL-2活性物质处理的病原菌接种寄主植物后,其致病性减弱、病斑扩展减慢。     

新疆天然胡杨林和野生骆驼刺丛枝菌根真菌多样性研究初报

为探明新疆常见的 2 种建群植物胡杨(Populus euphratica)和骆驼刺(Alhagi sparsifolia)丛枝菌根真菌的侵染状况、群落的种类和分布,在塔里木河中游和昌吉老龙河下游的胡杨林分别采集了 13 个土壤和根系样,在骆驼刺根周围分别采集了 8 个土壤和根系样,对土样中丛枝菌根真菌的种类和根系菌根的侵染状况进行了分析.结果表明:胡杨根周围 AM 真菌的优势种为缩球囊霉(Glomus constrictum)、大果球囊霉(G.macrocarpum)、沙荒球囊霉(G.deserticola)、透光球囊霉(G.diaphanum)和象牙白球囊霉(G.eburneum).骆驼刺根周围 AM 真菌的优势种为沾屑多样孢囊霉(Diversispora spurcum)、摩西球囊霉(G.mosseae)和聚丛球囊霉(G.aggregatum).胡杨根系侵染频度和侵染强度分别可达80%和100%,骆驼剌根系侵染频度和侵染强度分别达65%和90%.说明胡杨和骆驼刺是丛枝菌根依赖性很强的植物,且丛枝菌根真菌的多样性也十分丰富.     

Genetic resistance to bacterial blight disease in Persian walnut

Bacterial blight disease of Persian walnut (Juglans regia, L.), caused by Xanthomonas arboricola pv. juglandis (Xaj), leads to significant nut losses in northern, central and western areas of Iran. To identify the natural sources of resistance to disease in the endemic walnut genotypes of Iran, sixteen walnut genotypes, collected from different areas of Hamedan province, were inoculated with Xaj in a randomized complete block design with five replicates for each genotype. Two-year old genotypes were gently sprayed with a suspension of bacteria adjusted to approximately 2 × 10⁹ cfu ml⁻¹ of distilled water in May. Infected leaves were rated for disease 28 and 42 days after inoculation, using a 0 to 5 severity scale, based on the number, size and distribution of lesions on the leaves. Data analyses showed that there were variations among genotypes in response to pathogen. Upon inoculation by bacterial suspension genotype 94 showed the highest resistance to both disease incidence and its progress after 4–6 weeks of infection. Genotype 65 showed high susceptibility to disease and genotype 69 showed high susceptibilities both to disease incidence and its progress after 4–6 weeks of infection.     

Spread of seed-borne <Emphasis Type="Italic">Erwinia rhapontici</Emphasis> in bean,pea and wheat

Studies were conducted in the laboratory and greenhouse to determine the distribution of Erwinia rhapontici in plants arising from naturally infected seeds of pea or artificially inoculated seeds of bean and wheat, and whether the pathogen is transmitted to the subsequent generation of seeds. Infected seeds were planted in pots of Cornell mix in the greenhouse, and sampled at specified intervals throughout the plant growth cycle (seedling stage, elongation stage, flowering stage, seed formation stage, and maturity). Plating of surface sterilized lateral roots, tap roots, basal stems, mid-stems, apical stems, petioles, pods, and seeds of pea and bean, and of lateral roots, sub-crown internodes, basal stems, mid-stems, apical stems, peduncles, glumes, and seeds of wheat revealed that the bacterial pathogen spread from infected seeds to the lower parts of the plant tissues, but failed to spread further to the seeds produced on these plants. The study concludes that E. rhapontici did not establish systemic infection throughout the plants. Possible mechanisms of infection of seeds are discussed.     

中国狭螨属种类记述(真螨目:粉螨科)

狭螨属在国内仅知 3个种 ,本文记述该 3种的一般形态特征、在国内的分布、寄主或栖场所等 ,并列出 2种成螨的检索表     

不同Xenorhabdus spp菌株培养物游离氨基酸的含量分析

本文测定了在加入六个 Xenorhabdus luminescens 菌株和 X.nematophilus A24菌株后,一种豆粉鸡蛋线虫培养基游离氨基酸含量的变化.Xenorhabdus luminesces 菌株和 X.nematophilus A24菌株培养物中游离氨基酸的含量差别明显,后者未测出谷氨酸,苯丙氨酸极微;而这两种氨基酸在 X.luminescens 菌株中都占很大比例,Xenorhabdus luminescens不同的菌株培养物中游离氨基酸的含量变化很大,这可能反映出各菌株含氮代谢的差别.但这些变化与线虫对细菌的营养专化性未见直接的相关.     

食源性单核细胞增生李斯特菌lmoF2365_0037基因克隆及序列分析

为了对食源性单核细胞增生李斯特菌LM5567的lmoF23650037基因进行克隆和序列分析。试验利用PCR方法对lmoF23650037基因进行扩增,连接pMD19-T载体进行克隆,筛选阳性菌株进行测序比对分析。结果显示:扩增获得的lmoF23650037基因序列长为548 bp,克隆得到lmoF23650037基因的阳性转化子;生物信息学分析表明:lmoF23650037蛋白属于跨膜蛋白,无信号肽序列;二级结构中无规则卷曲和延伸链比例较大,分别是46.31%和32.89%;序列比对结果表明,LM5567株lmoF23650037基因核苷酸序列与02-6680株(4b,奶酪,加拿大)、10-0811株(1/2b,螃蟹,加拿大)、10-0809株(4b,粪便,加拿大)、81-0558株(4b,脑脊髓液、加拿大)、02-1103株、02-1792(4b,奶酪,加拿大)、81-0861株(4b,卷心菜,加拿大)相似性均为100%;LM5567 lmoF23650037基因编码的氨基酸序列与上述菌株相似性均为93.3%。本试验成功克隆了lmoF23650037基因,为进一步探究lmoF23650037基因的功能奠定了基础。     

加强生长育肥猪的饲养管理减少疾病的发生

在整个养猪生产中,育肥是养猪的最后一个生产环节,是检测猪种选择是否正确,营养饲料是否适合,饲养技术是否过硬,疫病防控是否完善的关键,不仅关系到市场供应,而且对猪场经济效益有着重要影响,也是发展养猪生产的最终目的。     

食用菌生产企业社会责任与财务绩效的互动关系分析

食用菌生产企业的社会责任是决定企业可持续发展的关键因素,同时对企业的财务绩效存在多方面影响。基于已有文献研究结论,通过构建回归模型对食用菌生产企业社会责任与财务绩效的相关性进行分析。结果表明,食用菌生产企业对股东、供应商、消费者、政府和社区所承担的社会责任与财务绩效具有正相关关系;而食用菌生产企业对员工承担的社会责任与财务绩效的相关性不显著。