Occurrence of dark septate endophytes in Nothofagus seedlings from Patagonia,Argentina

Temperate forests of southern Argentina and Chile cover a wide latitudinal and altitudinal range on both sides of the Andes, with Nothofagus species being one of the main tree species. Most of the larger remnants are protected within the limits of national parks and forest reserves. However, some of these are invaded by exotic conifers such as Pseudotsuga menziesii. In order to better understand the mycorrhizal condition within the Nothofagus–P. menziesii interaction, transects were established at six study sites along the effective recruitment area. Three treatments were established: Nothofagus forest without P. menziesii invasion (Forest), Nothofagus–P. menziesii matrix (Interface) and P. menziesii plantation lacking Nothofagus specimens (Plantation). A 2 kg mixed soil sample was taken at each treatment site and kept in brand-new plastic bags. A soil bioassay with Nothofagus seedlings acting as baits was set to evaluate the mycorrhizal inoculum potential and soil-fungi composition at each sampling treatment. Forty percent of the evaluated seedlings were found to be colonised by dark septate endophytes (DSE) fungi. Ectomycorrhizal colonisation percentage was significantly higher in plants growing in Forest soils (mean = 57.77%) when compared with Interface (mean = 42.53%) and Plantation (mean = 44.65%). The high incidence of DSE in young roots of Nothofagus seedlings in this study supports the hypothesis that DSE might be pioneering colonisers of young tree seedlings in secondary successional environments. For future interventions in the forest, either with productive or protective intentions, it should be taken into account the incidence of these fungi, which may have an important positive role in Nothofagus forest post-invasion recovery.     

内生菌在植物生长中的作用及西洋参内生菌研究

植物内生菌是一类种类丰富、生物学功能多样的微生物,具有重大的研究意义和潜在的应用价值。综述了植物内生菌在多样性、防病虫害、促生方面的研究现状,并对西洋参内生菌的分离、抑菌菌株的筛选和次生代谢产物的鉴定检验进展进行了总结,提出西洋参内生菌研究过程中存在的问题及其主要的研究方向,并展望了植物内生菌的开发利用前景。     

Inhibition of Bacterial Quorum Sensing by Extracts from Aquatic Fungi: First Report from Marine Endophytes

In our search for quorum-sensing (QS) disrupting molecules, 75 fungal isolates were recovered from reef organisms (endophytes), saline lakes and mangrove rhizosphere. Their QS inhibitory activity was evaluated in Chromobacterium violaceum CVO26. Four strains of endophytic fungi stood out for their potent activity at concentrations from 500 to 50 μg mL⁻¹. The molecular characterization, based on the internal transcribed spacer (ITS) region sequences (ITS1, 5.8S and ITS2) between the rRNA of 18S and 28S, identified these strains as belonging to four genera: Sarocladium (LAEE06), Fusarium (LAEE13), Epicoccum (LAEE14), and Khuskia (LAEE21). Interestingly, three came from coral species and two of them came from the same organism, the coral Diploria strigosa. Metabolic profiles obtained by Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS) suggest that a combination of fungal secondary metabolites and fatty acids could be the responsible for the observed activities. The LC-HRMS analysis also revealed the presence of potentially new secondary metabolites. This is, to the best of our knowledge, the first report of QS inhibition by marine endophytic fungi.     

Germination response of endophytic Festuca rubra seeds in the presence of arsenic

Epichloë fungal endophytes colonize the intercellular space of aerial organs of their plant hosts without causing symptoms. These symbionts are known to improve the performance of their host grasses in some situations of biotic and abiotic stress, leading to the suggestion that they can be used to improve grass tolerance to contaminants. The grass Festuca rubra is a host of the endophyte Epichloë festucae. We used two half‐sib lines of F. rubra, each line composed of infected (E+) or endophyte‐free (E?) seeds, to study the effect of varying levels of arsenic (6, 12, 25, and 50 mg L^?1), and of the endophyte in seed germination and radicle growth. The results showed that seed germination was not significantly affected by arsenic (As) levels lower than 25 mg L^?1, indicating that this grass has a relatively high tolerance of As at the germination stage. The decrease in germination observed at 25 and 50 mg L^?1 was due to increased seed mortality and to the reversible inhibition of the germination of viable seeds caused by As. The presence of the endophyte did not change the germination response to arsenic of one line, but affected negatively the germination of the other line. In contrast to the process of germination, radicles of E+ seeds of both lines were longer than those of endophyte‐free seeds. The results of this work indicate that Epichloë endophytes can affect the performance of some F. rubra genotypes when As is present in the soil.     

欧李高效再生体系的建立

研究旨在利用植物组织培养技术,筛选出引进资源品种（系）SN6、SN7和自育品系YC24的最适培养基,确定3个欧李品种的再生体系,为欧李高效快速规模化繁殖提供技术性支持。以3个欧李品种（系）为材料,对外植体的消毒方式、分化、增殖和生根培养阶段的最适培养基和激素配比进行研究。结果表明,头孢霉素浓度为100 mg/L时,外植体存活率最高、污染率最低;SN6、SN7的最适分化培养基为MS+ 0.5 mg/L 6-BA+ 1.0 mg/L ZT+ 0.05 mg/L IBA,YC24的最适分化培养基为MS+ 0.5 mg/L 6-BA+ 0.5 mg/L ZT+ 0.05 mg/L IBA;SN6的最适生根培养基为1/2MS+ 0.2 mg/L NAA+ 0.1 mg/L IBA+ 1.0 g/L活性炭,SN7、YC24的最适壮苗生根一步培养基为1/2MS+ 0.05 mg/L NAA+ 0.2 mg/L IBA。本研究建立了欧李嫩枝快速繁殖体系,可为优良种质的后续练苗移栽、扩大培养和推广应用提供参考。     

植物内生菌醇提取物“易丰收“对辣椒农艺性状及生理生化指标的影响

以辽椒19为试验材料,分别在辣椒缓苗后期、开花前期和座果期喷施植物内生菌醇提取物"易丰收",探究其对辣椒农艺性状及生理生化指标的影响。在喷施"易丰收"后10 d、20 d和30 d时测定辣椒农艺性状及生理生化指标。结果表明:喷施"易丰收"后10 d、20 d和30 d,辣椒的株高、茎粗、株幅及叶片中可溶性糖含量、叶绿素含量相比对照组分别有了不同程度提高,并且丙二醛含量均比对照组要低。     

生防链霉菌SAT1的分离、鉴定及其对辣椒疫霉的生物防治潜力

辣椒疫霉引起的植物病害使农业遭受了巨大的经济损失,环保、经济实用的混合微生物菌剂防治策略是当前的最新发展趋势.试验从6种药用植物分离得到15株植物内生菌,平板拮抗实验筛选得到拮抗链霉菌SAT1,经鉴定为Streptomyces anandii,其发酵液粗提物和挥发性物质对辣椒疫霉菌丝生长有明显抑制作用.接种链霉菌SAT1的孢子液可提高辣椒苗对辣椒疫霉的抗性并明显促进辣椒苗的生长.     

欧李内生促生菌分离、鉴定及促生、耐盐碱特性

为获得欧李(Cerasus humilis)根系优良内生促生菌,以欧李根系为研究材料,采用组织匀浆法分离纯化可培养内生细菌,测定其固氮、解磷、溶磷、合成植物生长素IAA(吲哚乙酸)和耐盐碱特性,并通过16S rRNA序列系统发育分析进行初步鉴定.结果显示:分离的7株菌均表现出一定的促生潜力,菌株固氮酶活性在50.64～...     

Incidence and viability of Acremonium endophytes in tall fescue accessions from North Spain

The tall fescue (Festuca arundinacea Schreb.) seed collection of the Centro de Investigaciones Agrarias de Mabegondo was surveyed to determine Acremonium infection rates. One hundred seeds from each of 19 accessions were microscopically examined for endophyte. Seventeen accessions (90%) contained endophyte with a range of 7 to 100%. Leaf sheaths of seedlings from the infected accessions were examined to determine the percentage of infection with viable endophyte. Only seven (41%) of the seventeen infected accessions collected and stored in 1995 at 4°C and 45–50% relative humidity contained viable endophyte with a range of 70 to 100%. While existing germplasm collections of Festuca arundinacea can provide only a small basis of Acremonium germplasm for study, newly collected Festuca arundinacea accessions will offer a greater diversity of Acremonium genotypes.