黏菌生活周期不同阶段细胞核的观察

在显微和亚显微2个水平对黏菌孢子、原质团和菌核中细胞核进行了观察。试验结果表明,幼孢子中细胞核着色明显,原质团中细胞核在荧光染料染色的条件下易于被观察到,而菌核中的细胞核即使在电镜下也难以确定。     

暗褐网柄牛肝菌菌核形成相关基因分析

【背景】暗褐网柄牛肝菌(Phlebopus portentosus)是第一个能够人工栽培的食用牛肝菌,人工栽培过程中,不同菌株会形成数量不等的菌核。【目的】探明不同菌株产核差异机制。【方法】采集多菌核(JH1)、寡菌核(JH2)菌株的成熟菌核及无菌核(JH3)菌株培养相同时间的菌丝体进行转录组测序,分析差异表达基因对菌核形成的作用和功能。【结果】KEGG富集分析显示,JH2 vs. JH1互比,苯丙氨酸、酪氨酸和色氨酸的生物合成,精氨酸和脯氨酸代谢,半胱氨酸及蛋氨酸代谢显著富集;JH3 vs. JH1互比,乙醛酸和二羧酸代谢显著富集;JH3 vs. JH2互比,谷胱甘肽、乙醛酸和二羧酸代谢显著富集。菌核形成相关基因分析显示,从JH2 vs. JH1、JH3 vs. JH1和JH3 vs. JH2的差异表达基因中分别筛选到69、118和82条与信号转导、感知刺激、防御、碳水化合物活性酶等有关的基因,其中碳水化合物活性酶基因数量最多。三个比较组共有的碳水化合物活性酶基因在JH1中的表达量高于JH2、JH3,表明JH1更能充分利用底物营养以形成更多菌核。【结论】本研究从转录组水平初步分析了暗...     

The occurrence of sclerotium rot on Momordica charantia caused by Sclerotium rolfsii in Korea

Sclerotium rolfsii is one of the most destructive pathogens and thought to affect a broad range of plant hosts. In July 2014, an occurrence of sclerotium rot was observed on bitter melon (Momordica charantia L.) in Jinju, South Korea. The rot symptoms were most developed on stems and fruit near the soil line, and infected bitter melon plants withered and eventually died. White mycelial mats with numerous sclerotia were produced on diseased stems and fruit near the soil surface. Based on the morphological characteristics, pathogenicity tests, and DNA sequencing and phylogenetic analysis of the internal transcribed spacer (ITS) ribosomal RNA (rRNA) gene region, the causal fungus was identified as S. rolfsii Saccardo. This is the first report of sclerotium rot caused by S. rolfsii on bitter melon in Korea. The recent occurrence of sclerotium rot on bitter melon poses a potential threat to its production in Korea.     

Survival of Rhizoctonia solani AG‐1 IA,the Causal Agent of Rice Sheath Blight,under Different Environmental Conditions

The ability of Rhizoctonia solani AG‐1 IA, the causal agent of rice sheath blight, to survive in diseased rice straw and as sclerotia and mycelia was investigated. After storage for 10 months at 4°C, 25°C and non‐air‐conditioned natural room temperature (NRT, temperature range from 6°C to 35°C), sclerotia placed inside a desiccator, soaked in sterile water or immersed in wet paddy soil were viable. In contrast, only 15% of sclerotia in dry paddy soil survived. Survival of mycelia was severely affected by temperature and humidity. After 10 months in a desiccator at 4°C, 55% of mycelia samples could survive, whereas at 25°C and NRT, mycelial samples survived for only 7 and 5 months, respectively. However, mycelia stored in sterile water at constant temperatures (4°C or 25°C) survived for 10 months. A certain amount of UV radiation had no obvious effect on the survival of sclerotia or mycelia. The survival rate of the fungus in diseased rice straw stored for 16 months could reach 100% at 4°C, 50% at 25°C and 35% at NRT. The survival rates of the pathogen in diseased rice straw buried in dry, wet and flooded paddy soils after 10‐month storage at NRT were 75, 100 and 100%, respectively, indicating that soil humidity is a crucial factor for the survival of this fungus.     

Isolation and characterization of glutathione reductase from Physarum polycephalum and stage-specific expression of the enzyme in life-cycle stages with different oxidation-reduction levels

Physarum polycephalum has a life cycle with several distinct phases that have different oxidation-reduction requirements. To investigate the relationship between the life cycle and the oxidation-reduction state, we isolated glutathione reductase (GR; EC 1.6.4.2) from Physarum microplasmodia. The enzyme was found to be a homodimer with a subunit M(r) of 49,000, and K(m) values for oxidized glutathione and NADPH of 40 and 28.6 microM, respectively. We then constructed a cDNA library from microplasmodium mRNA and cloned GR cDNA from the library. The isolated cDNA consisted of 1,475 bp encoding a polypeptide of 452 amino acids. The amino acid sequence similarity was about 50% with GRs of other organisms, and several conserved sequence motifs thought to be necessary for activity are evident in the Physarum enzyme. Escherichia coli transformed with an expression vector containing the cDNA synthesized the active GR. Genomic Southern blot analysis indicated that the GR gene is present as a single copy in the Physarum genome. Immunoblot analysis and RT-PCR analysis detected GR mRNA expression in the microplasmodium, plasmodium, and sclerotium, but not in the spore or flagellate. GR activity was low in the spore and flagellate. These results suggest that the glutathione oxidation-reduction system relates to the Physarum life cycle.     

恒温和变温培养对羊肚菌菌丝生长及菌核形成影响的比较研究

为了探究恒温和变温培养对羊肚菌菌丝生长和菌核形成的影响,设置-9℃-30℃的7个恒温处理,3个变温处理,通过观察和记录在两种不同培养方式下菌丝的长势、生长速度、菌落干重、产核时间、菌核数量等内容,从而比较出恒温和变温培养对羊肚菌菌丝生长和菌核形成的影响效果。结果表明,在恒温条件下羊肚菌菌丝生长和菌核发育比变温好,20℃最适宜菌丝生长,菌丝生长速度较快,菌落干重最大;25℃最适宜菌核生长发育,产核最早。菌核数量最多。     

梯棱羊肚菌外源营养作用的影响因素

外源营养袋的应用是国内羊肚菌大田栽培成功的关键技术之一,但其作用机理和影响因素一直没有得到充分的解析。本研究首先于室内建立一个外源营养模型,确认模型中外源营养模块可以向外输出营养,且被梯棱羊肚菌菌丝利用。通过模型实验发现,外源营养添加到贫瘠培养基时,菌体生物量的增加显著高于营养丰富的培养基;在梯棱羊肚菌生长的不同阶段添加外源营养,菌核形成位置不同,并影响生物量的增加,在菌核起始阶段添加,主培养基的生物量增加最多;外源营养的添加位置、块数等因素在本模型中没有检测到对生物量的影响。外源营养使用聚丙烯袋包裹和不包裹比较发现,包裹组的主培养基内生物量增速和总量低于无包裹组,而外源营养块内趋势相反,但最终两组之间外源营养块与主培养基内生物量总和没有显著差异。使用滤纸和铝箔包裹外源营养时,对生物量的影响和聚丙烯袋材质没有显著差别。外源营养碳氮比20:1时,最有利于主培养基生物量的积累。本研究建立的外源营养研究模型得到的结论与大田栽培有较好的一致性,通过模型发现了实际栽培中不容易观察到的现象,有助于对外源营养袋作用机理进行深入研究。     

Chemical components and molecular mass of six polysaccharides isolated from the sclerotium of Poria cocos

Six polysaccharides were extracted sequentially from the fresh sclerotium of Poria cocos cultivated in China using 0.9% NaCl (PCS1), hot water (PCS2), 0.5M NaOH (PCS3-I and PCS3-II), and 88% formic acid (PCS4-I and PCS4-II). Their chemical and physical characteristics were determined using infrared spectroscopy (IR), gas chromatography (GC), GC-MS methylation analysis, 13C NMR spectroscopy, elementary analysis (EA), protein analysis, size exclusion chromatography combined with laser light scattering (SEC-LLS), light scattering (LS), and viscometry. The results indicated that the polysaccharides PCS1, PCS2, and PCS3-I were heteropolysaccharides containing D-glucose, D-galactose, D-mannose, D-fucose, and D-xylose; the predominant monosaccharide was D-glucose except for PCS1 where it was D-galactose. PCS3-II, the main component of the sclerotium of P. cocos, was a linear (1-->3)-beta-D-glucan of high purity. PCS4-I consisted of (1-->3)-beta-D-glucan with some beta-(1-->6) linked branches. PCS4-II was mainly composed of (1-->3)-beta-D-glucan containing some glucose branches. The M(w) values of the six polysaccharides PCS1, PCS2, PCS3-I, PCS4-I in 0.2M NaCl aqueous solution, PCS3-II, and PCS4-II in dimethyl sulfoxide (Me(2)SO) were determined to be 11.6 x 10(4), 20.8 x 10(4), 17.1 x 10(4), 9.1 x 10(4), 12.3 x 10(4), and 21.1 x 10(4), respectively. The six polysaccharides in aqueous solution or Me(2)SO exist as flexible chains.     

Deficiency of the melanin biosynthesis genes SCD1 and THR1 affects sclerotial development and vegetative growth,but not pathogenicity,in Sclerotinia sclerotiorum

The fungus Sclerotinia sclerotiorum is a necrotrophic plant pathogen causing significant damage on a broad range of crops. This fungus produces sclerotia that serve as the long‐term survival structures in the life cycle and the primary inoculum in the disease cycle. Melanin plays an important role in protecting mycelia and sclerotia from ultraviolet radiation and other adverse environmental conditions. In this study, two genes, SCD1 encoding a scytalone dehydratase and THR1 encoding a trihydroxynaphthalene reductase, were disrupted by target gene replacement, and their roles in mycelial growth, sclerotial development and fungal pathogenicity were investigated. Phylogenetic analyses indicated that the deduced amino acid sequences of SCD1 and THR1 were similar to the orthologues of Botrytis cinerea. Expression of SCD1 was at higher levels in sclerotia relative to mycelia. THR1 was expressed at similar levels in mycelia and sclerotia at early stages, but was up‐regulated in sclerotia at the maturation stage. Disruption of SCD1 or THR1 did not change the pathogenicity of the fungus, but resulted in slower radial growth, less biomass, wider angled hyphal branches, impaired sclerotial development and decreased resistance to ultraviolet light.     

贵州茯苓优良菌株的筛选

以l6个不同来源的茯苓菌株为试验材料,分别进行了菌丝生长初筛、复筛、高产性能筛选、遗传稳定性分析等一系列优良菌株筛选试验,获得4个长势强、产量高、商品性好、遗传稳定、适合贵州人工栽培的优良菌株;并在此基础上初步建立优良茯苓菌株筛选模型。