荧光假单胞菌对食用菌的促生作用及其机理

从小麦根际分离到1株对食用菌有较强促生作用的荧光假单胞菌,命名为假单胞菌P2-10(Pseudomonas sp.P2-10)。该菌株与平菇天达300(Pleurotus ostreatus Td 300)、杏鲍菇杏6(Pleurotus eryngii X6)或鸡腿菇瑞7(Coprinus comatus R7)混合培养,可显著提高这些食用菌菌丝生长速度及诱导并促进子实体的形成和发育。假单胞菌P2-10对食用菌的促生作用来自其代谢产物,可能是通过其1-氨基环丙烷-1-羧酸(ACC)脱氨酶降解食用菌产生的ACC、减少食用菌乙烯的合成及乙烯对菌丝生长和子实体发育的抑制作用。     

Hydrolytic enzymes and ability of arbuscular mycorrhizal fungi to colonize roots

The production of hydrolytic enzymes from external mycelia associated with roots and colonized soybean roots (Glycine max L.) inoculated with different arbuscular-mycorrhizal (AM) fungi of the genus GLOMUS:, and the possible relationship between these activities and the capacity of the AM fungi to colonize plant roots was studied. There were differences in root colonization and plant growth between the GLOMUS: strains, and also between two isolates of G. mosseae. Hydrolytic activities in the root and external mycelia associated with roots differed in the AM fungi tested. Correlations were only found between the endoxyloglucanase activity of the external mycelia associated with roots of the AM fungi tested and the percentage root colonization or plant growth. However, hydrolytic activities of roots colonized by the different endophytes correlated with those of external mycelia. The hydrolytic activities were not qualitatively different because the endoxyloglucanase from AM colonized roots and the external mycelia did not show a high degree of polymorphism in the different species of fungus tested. The possible role of the hydrolytic activity of external hyphae of AM fungi was discussed as a factor affecting fungal ability to colonize the root and influence plant growth.     

Measuring external mycelia production of ectomycorrhizal fungi in the field: the soil matrix matters

Assessing mycorrhizal fungi production in field settings has been hindered by the inability to measure external mycelia. Recently, external mycelia production was measured in the field using a novel in-growth core technique with acid-washed sand as the in-growth matrix. Here, we tested the assumption that external mycelia production in acid-washed sand is representative of that in native soil. External mycelia production was estimated as the difference in fungal growth between closed (allowing only saprotrophic fungal production) and open (allowing mycorrhizal and saprotrophic fungal production) cores using a factorial design of soil matrices (acid-washed sand vs native) and fertilization treatments (control vs nitrogen (N)) in a longleaf pine (Pinus palustris) plantation. In native soils, the ectomycorrhizal to saprotrophic fungal biomass signal was strong and consistent facilitating the assessment of external mycelia production, which was 300% higher than corresponding rates in acid-washed sand and inversely correlated with soil N. These results demonstrate the efficacy and importance of using native soil as the in-growth matrix to measure ectomycorrhizal fungi external mycelia production in field settings.     

S-159-06菌株活性产物对植物病原菌的抑菌谱及拮抗机理初探

对S-159-06菌株活性产物的抑菌谱及其拮抗机理作了初步研究,结果表明：S-159-06活性产物具有较广的抑菌谱,对多种病原真菌和细菌具有较好的抑制作用;S-159-06活性产物能强烈抑制病原菌菌丝的生长和孢子的萌发,可引起病原菌菌丝扭曲,菌丝膨大成串珠状,分枝增多,分枝顶端膨胀后细胞壁破裂,原生质外溢,产生溶菌作用;使分生孢子数减少,孢子萌发畸形,萌发率降低;在温室条件下,S-159-06活性产物不仅能阻止番茄灰霉病菌菌丝的入侵,而且在植物体内有内吸作用,对已侵入的菌丝有较好的治疗作用。     

MYCELIUM OF LIMB RUST FUNGI

Limb rust is a killing disease of hard pines caused by Peridermium spp. Study of tissue sections shows that growth of limb rust fungi differs from growth of other plant rusts: (1) longitudinal spread is mainly by hyphal growth within host tracheids; (2) hyphae grow radially in mature xylem, deep in host sapwood; (3) in larger stems mycelia avoid (rather than concentrate in) bark and outer xylem rings; and (4) mycelia become much larger than any previously described for rust fungi. Antibiotics being tested as therapeutants are unlikely to be effective against such deep-seated mycelia.     

不同磷水平下外生菌根真菌对铅的耐性反应

采用液体离体培养的方法,研究了不同磷和铅水平对3个外生菌根真菌生物量、ZC₁菌丝含磷量和含铅量的影响.结果表明,不同水平的磷和铅胁迫下,菌种ZC₁和ZC₂的生物量显著高于菌种GV(Gomphidius viscidus);低磷时（0.16 mmol·L^-1）,3个菌种的生物量随着铅浓度的增加都受到了抑制,在较高的磷水平下(0.81和2.42 mmol·L^-1),铅浓度的增加显著的抑制了菌种GV的生物量,但对菌种ZC₁和ZC₂的生物量没有显著抑制.GV的菌丝含铅量在各处理水平下都显著高于ZC₁和ZC₂.同一铅水平下,GV的菌丝含磷量在低磷时高于ZC₁和ZC₂,在较高磷浓度时却低于ZC₁和ZC₂;铅浓度的增加降低了菌种ZC₂和GV的菌丝含磷量,但菌种ZC₁的菌丝含磷量没有受到显著的抑制.与无污染地采集的菌种GV相比,污染地采集的菌种ZC₁和ZC₂表现出快速生长、低铅积累以及高磷吸收的特点,显示出较高的抗环境胁迫能力.     

木屑添加对刺芹侧耳菌丝共生细菌多样性和群落结构的影响

细菌作为许多真菌的共生菌,能够有效地促进真菌的代谢生长,而细菌多样性及群落结构能够反映真菌的生长和利用营养物质的状况。本研究利用基于细菌16S rRNA 基因V3-V4区的高通量测序技术分析不同木屑用量对刺芹侧耳菌丝共生细菌群落结构和多样性的影响。结果表明: 5组样品共检测细菌25门52纲114目199科406属,主要的优势菌门为变形菌门(35.0%～85.9%)和厚壁菌门(6.5%～38.4%),优势菌属为不动杆菌属(14.8%～71.6%)和假单胞菌属(1.7%～22.3%)。相较于完全培养基,添加木屑能够提高刺芹侧耳菌丝中的细菌多样性,并使其中优势细菌10个门类、9个属类结构发生显著变化。刺芹侧耳菌丝在5 g木屑培养基上的菌丝生长速度最快,菌丝浓密,边缘整齐,长势优于其他几类培养基;假单胞菌属和乳酸菌属丰度及物种多样性在5 g木屑培养基上都具有一定的优势,且假单胞菌属和乳酸菌属丰度与菌丝长势具有显著的正相关性。木屑作为重要碳源之一,对刺芹侧耳生长发育及其共生细菌群落结构和多样性都有显著影响,这为进一步探索木屑及共生细菌对刺芹侧耳生长发育影响的机理研究奠定了基础。     

Are stag beetles fungivorous?

Stag beetle larvae generally feed on decaying wood; however, it was unknown whether they can use wood-rotting fungi alone as food. Here, to clarify this, newly hatched larvae of Dorcus rectus (Motschulsky) (Coleoptera: Lucanidae) were reared for 14 days on artificial diets containing a fixed amount of freeze-dried mycelia of the following fungi: Bjerkandera adusta, Trametes versicolor, Pleurotus ostreatus, and Fomitopsis pinicola. The mean incremental gain in larval body mass was greatest on diets containing B. adusta, followed by T. versicolor, P. ostreatus, and F. pinicola. The growth rate of body mass correlated positively with mycelial nitrogen content of the different fungi. It also correlated positively with the mycelial content of B. adusta in the diet. Addition of antibiotics to diets with mycelia nearly halved larval growth, indicating that larvae were able to use fungal mycelia as food without the assistance of associated microbes although the microbes positively affected larval growth. Four newly hatched larvae reared on artificial diets containing B. adusta mycelia developed to the second instar in 21-34 days; and one developed to the third (=final) instar. This study provides evidence that fungi may constitute the bulk of the diet of D. rectus larvae.     

Regulation of hyphal morphogenesis by Ras and Rho small GTPases

The fungal kingdom is extremely diverse – comprised of over 1.5 million species including yeasts, molds and mushrooms. Essentially, all fungi have cell walls that contain chitin and the cells of most fungi grow as tube-like filaments called hyphae. These filamentous fungi, such as the mold Neurospora crassa, develop branched radial networks of hyphae referred to as mycelium. In contrast, non-filamentous fungi do not form radial mycelia, but grow as single cells, which reproduce by either budding or fission such as Saccharomyces cerevisiae or Schizosaccharomyces pombe, respectively. Finally, there are fungi that are capable of switching between single cell, yeast form growth and filamentous growth such as Candida albicans. The switch from yeast to filamentous growth in these so-called dimorphic fungi is a virulence trait in many human and plant pathogens. Highly conserved master regulators of all three fungal growth modes – filamentous, non-filamentous and dimorphic – are the Ras and Rho small GTPases, which spatially and temporally control cell polarity establishment and maintenance. This review summarizes the key roles of the Ras and Rho GTPases during hyphal morphogenesis in a range of fungi.     

The chitosan yield of zygomycetes at their optimum harvesting time

Fungi are a promising alternative source of chitosan. Fungi can be manipulated to give chitosan of more consistent and desired physico-chemical properties compared to chitosan obtained from crustacean sources. Chitosan was extracted from the mycelia of Rhizopus oryzae USDB 0602 at various phases of growth. The growth phase which produced the most extractable chitosan was determined to be the late exponential phase. In contrast to previous work on the screening of chitosan from fungal sources, mycelia of the fungi used in this study were harvested at their late exponential growth phase instead of at a fixed incubation time. The amount of extractable chitosan varied widely among the fungal strains. Gongronella butleri USDB 0201 was found to produce the highest amount of extractable chitosan per ml of substrate, followed by Cunninghamella echinulata and Gongronella butleri USDB 0428. However, in terms of yield of chitosan per unit mycelia mass, C. echinulata was the best strain among all fungi in the experiment. Therefore, besides G. butleri USDB 0201, C. echinulata can also be considered to be used in the commercial production of chitosan.     

丝状真菌液体深层发酵过程菌丝聚集的调控机制

丝状真菌是微生物发酵产品的重要表达体系,其液体深层发酵过程的典型特征是环境因素显著影响菌丝聚集,菌丝聚集影响发酵体系流变特性,进而影响质量传递、热量传递和动量传递,最终影响目标产物生物合成和生产效率。文中首先综述了丝状真菌形态调控的方法和策略,在此基础上针对丝状真菌菌丝生长和聚集过程的两大典型特征——顶端延伸生长和分枝生长,综述和展望了钙信号传导途径和几丁质生物合成途径对调控菌体聚集这一形态的重要意义。     

Vital Fluorochromes as Tracers for Fungal Growth Studies

Eight fluorescent dyes were tested for staining the spores or mycelia of six fungi and for their translocation into new growth when the preloaded spores or mycelia were incubated on agar coated coverslips. The dyes studied were Cellufluor, Nile red, fluorescein diacetate (FDA), carboxyfluorescein diacetate (CFDA), chloromethylfluorescein diacetate (CMFDA), aminochloromethyl coumarin (CMAC), and the carbocyanines DiIC₁₈(3) and DiOC₁₈(3). The fungi on which the dyes were tested included Botrytis cinerea, Fusarium oxysporum f.sp. lycopersici, Idriella bolleyi, Pythium oligandrum, Sclerotium cepivorum and Trichoderma. harzianum Most of the fluorochromes gave good initial staining of mycelia or spores; however, FDA fluorescence faded rapidly during excitation, making it impractical for use. Also, the spores and mycelia of B. cinerea and T. harzianum sometimes gave weak fluorescence with Nile red, and the spores and mycelia of I. bolleyi gave unusually weak fluorescence with Cellufluor. There were other variations of staining among the different dye/fungus combinations, but each fungus showed strong fluorescence with at least one dye. Cellufluor, CMFDA, CMAC and, to a lesser extent, CFDA and Nile red, were efficiently translocated into new growth from preloaded spores or mycelia, whereas FDA, DiIC₁₈(3) and DiOC₁₈(3) were not. The extent of translocation ranged from 0.1 to 1.2 mm in germ tubes arising from spores, and from 0.9 to 9.2 mm in mycelia extending from dye-loaded agar blocks. The findings suggest that fluorescent dyes could be used as markers or tracers in studies of fungal growth and differentiation.     

Lead and cadmium uptake in the marine fungi Corollospora lacera and Monodictys pelagica

This study provides observations on the effects of lead and cadmium ions on the growth of two species of marine fungi, Corollospora lacera and Monodictys pelagica. On solid media lead appeared to have no effect on the radial rate of growth of fungi. Exposure to increasing cadmium concentrations on solid media resulted in significant reduction (p < 0.05) in the radial mycelial growth rates of both fungi, especially in M. pelagica. These results reveal significant difference in species sensitivity toward cadmium and, essentially, insensitivity toward lead exposure. In liquid cultures, the metal content of mycelia (metal mass found in mycelium, in mg), and the concentration of metal in dry mycelium (metal mass in 1g of mycelium, in mg g(-1)) were both found to increase (p < 0.05) with the increase in the metal cation concentration, while mycelium dry mass decreased. As it was observed on solid media, cadmium cation affected more severely (p < 0.05) the growth of M. pelagica in liquid cultures. Ergosterol content of mycelia of C. lacera exposed to increasing cadmium cation concentration decreased, similarly to the trend observed for dry mycelial mass. It was found that ca. 93% of all lead sequestered by C. lacera is located extracellularly. M. pelagica was found to bioaccumulate over 60 mg of cadmium and over 6 mg of lead per 1 g of mycelium, while C. lacera bioaccumulated over 7 mg of cadmium and up to 250 mg of lead per 1 g of mycelium. Overall, the results indicate that both metal ions affect the growth of marine fungi with lead being accumulated extracellularly in the mycelia. Both metals accumulated by fungi may then enter the marine ecosystem food web, of which marine fungi are integral members.     

Wide-range antifungal antagonism of Paenibacillus ehimensis IB-X-b and its dependence on chitinase and beta-1,3-glucanase production

Previously, we isolated a strain of Bacillus that had antifungal activity and produced lytic enzymes with fungicidal potential. In the present study, we identified the bacterium as Paenibacillus ehimensis and further explored its antifungal properties. In liquid co-cultivation assays, P. ehimensis IB-X-b decreased biomass production of several pathogenic fungi by 45%-75%. The inhibition was accompanied by degradation of fungal cell walls and alterations in hyphal morphology. Residual medium from cultures of P. ehimensis IB-X-b inhibited fungal growth, indicating the inhibitors were secreted into the medium. Of the 2 major lytic enzymes, chitinases were only induced by chitin-containing substrates, whereas beta-1,3-glucanase showed steady levels in all carbon sources. Both purified chitinase and beta-1,3-glucanase degraded cell walls of macerated fungal mycelia, whereas only the latter also degraded cell walls of intact mycelia. The results indicate synergism between the antifungal action mechanisms of these enzymes in which beta-1,3-glucanase is the initiator of the cell wall hydrolysis, whereas the degradation process is reinforced by chitinases. Paenibacillus ehimensis IB-X-b has pronounced antifungal activity with a wide range of fungi and has potential as a biological control agent against plant pathogenic fungi.     

过量钠盐胁迫对3种外生菌根真菌生长和钠元素积累的影响*

通过测定3种外生菌根真菌-美味牛肝菌(Boletus edulis)、红绒盖牛肝(Xerocomus chtysenterort)和铆钉菇(Gomphidius viscidus)在Na2SO4和NaCl处理下的菌斑增长特性、生物量积累和菌丝中钠元素积累量显示,2种盐都没有影响菌丝的生长模式。但在0．1mol／L浓度下,NaCl显抑制了X．chrysertterort和G．viscidus的干重增长;在Na2SO4处理下,X．chrysenteron生物增长量比对照显增加,G．viscidus则降低,而2种盐处理对B．edtdis的生物量积累没有显影响。3供试菌种在2种盐处理下,其对钠元素的吸收和积累量差异显。NaCl处理下,X．chtysenteron菌丝积累的钠量最多,而在Na2SO4条件下,B．edulis菌丝中钠积累量显高于其他2菌种。     

Underground resource allocation between individual networks of mycorrhizal fungi

Fusions between individual mycelia of arbuscular mycorrhizal (AM) fungi have been observed in two-dimensional systems but never in soil systems. Here, phosphorus ((32)P) labelling was used to demonstrate nutrient transfer between individual mycelia and to investigate the possible role of anastomosis. Trifolium subterraneum colonized by Glomus mosseae were grown in root-retaining mesh bags, which were placed 20 cm apart. The mycelium of one plant, the donor, had access to (32)P-labelled soil placed adjacent to the mesh bag. Transfer of (32)P from the donor mycelium to the receiver plant was measured at three harvests. In a second-harvest control treatment the receiver was colonized by Glomus caledonium in order to determine whether transfer occurred by other means than hyphal fusions. Significant amounts of P were transferred to the receiver plant at the last harvests when the two mycelia of G. mosseae overlapped. The transfer probably occurred via anastomoses between the mycelia as no transfer of (32)P was detected between the mycelia of different fungi at the second harvest. The indicated ability of AM fungal mycelia to anastomose in soil has implications for the formation of large plant-interlinking functional networks, long-distance nutrient transport and retention of nutrients in readily plant-available pools.     

飞虱虫疠霉液培菌丝的凝胶化及其杀蚜活性*

用丙烯酰胺淀粉凝胶包埋飞虱虫疠霉(Pandora delphacis)液培菌丝,制成含营养和不含营养的虫霉凝胶,并测试其产孢能力及对桃蚜(Myzus persicae)的侵染力。经持续9 d产孢观察,相同菌丝量条件下,含营养的虫霉凝胶的累计产孢量(1910.9 个/mm2）为不含营养的虫霉凝胶的3.14倍（608.5个/mm2）和对照（纯液培菌丝）的4.69倍（387.5个/mm2）。用虫霉凝胶的“孢子浴”接种桃蚜居群（成蚜与不同龄期若蚜的混合）,在2.23个/mm2的剂量下,接种后第7 d的死亡率达82.3%。结果表明,丙烯酰胺淀粉凝胶作为载体材料,与飞虱虫疠霉的基本生物学特性相容,对虫霉的剂型化具有重要意义     

Monoclonal antibodies incorporated into Neotyphodium coenophialum fungal cultures: inhibition of fungal growth and stability of antibodies.

Three monoclonal antibodies (mAbs) produced against proteins from the tall fescue (Festuca arundinacea Schreb.) fungal endophyte Neotyphodium coenophialum hybridize exclusively to a fungal protein under denaturing conditions. The protein is approximately 88 kDa in size. These mAbs were individually incorporated into liquid medium to determine their effects on fungal growth in culture. Neotyphodium-specific mAbs inhibited fungal growth for the duration of the study. Fungal cultures grown in the presence of Neotyphodium-naive mAbs or in the absence of all mAbs grew unimpeded. Bright-field microscopy and immunohistochemical studies of cultures containing Neotyphodium-specific mAbs revealed a change in mycelia morphology with clumps exhibiting a gelatinous matrix containing sparse hyphae, while cultures receiving Neotyphodium-naive mAbs in medium demonstrated unrestricted growth with overlapping and branched hyphae. In liquid culture devoid of fungal isolates, mAbs were stable and detected throughout the experiment, but were below threshold detection levels within 15 min following inclusion in liquid cultures containing Neotyphodium spp., indicating rapid binding to fungal mycelia. Monoclonal antibodies may provide a new method to help control plant pathogenic fungi where chemical or genetic means are not feasible.     

1‐Phenyl‐3‐pentanone,a Volatile Compound from the Edible Mushroom Mycoleptodonoides aitchisonii Active Against Some Phytopathogenic Fungi

Volatiles produced by mycelia of mushrooms with aromatic odour were investigated for their antifungal activity against plant‐pathogenic fungi. The results of the screening of 23 species of basidiomycetes revealed that volatile substances from mycelia of Mycoleptodonoides aitchisonii (TUFC10099), an edible mushroom, strongly inhibited the mycelial growth, spore germination and lesion formation on host leaves of some plant‐pathogenic fungi including Alternaria alternata, A. brassicicola, A. brassicae, Colletotrichum orbiculare and Corynespora cassiicola. The volatile compounds were isolated from the culture filtrate of M. aitchisonii, and 1‐phenyl‐3‐pentanone was identified as a major antifungal volatile. The compound had significantly inhibitory activity against plant‐pathogenic fungi at 35 ppm. This is the first report that the volatile compound produced by mycelia of M. aitchisonii has antifungal activity against plant‐pathogenic fungi.     

Triterpeneglycosides as Inhibitors of Fungal Growth and Metabolism

Avenacin, the resistance factor ioat roots against Ophiobolus graminisi ν graminis, and a related triterpeneglycoside, aescin, inhibited growth of various fungi, while the growth of a few fungi was unaffected. The triterpenoidal saponins tested seemed to be fungicidal, as the mycelia did not grow after exposure to the inhibitors. The fungicidal effect, however, depended on the medium used. The inhibitors did not seem to act primarily on the endogenous respiration, since the oxygen uptake, although much reduced, continued after the time required to destroy the growth capacity. The leakage of UV-absorbing substances from fungi, sensitive to the inhibitors, and the decrease of UV-absorbing substances in the transient pool of the cells indicate a change in the cell membrane.