Mycelium

About: Mycelium is a research topic. Over the lifetime, 8923 publications have been published within this topic receiving 170993 citations.

Dose effect in the dual inoculation of an ectomycorrhizal fungus and a mycorrhiza helper bacterium in two forest nurseries

Abstract: We inoculated disinfected soil at two Douglas-fir bareroot forest nurseries with three doses (8×105, 8×107 and 8×109 cfu m−2) of the rifampin-resistant mycorrhiza helper bacterium Pseudomonas fluorescens strain BBc6R8 and the ectomycorrhizal fungus Laccaria bicolor strain S238N. In one of the two nurseries, two doses of fungal inoculum (50 and 100 mg m−2 dry weight (DW) mycelium entrapped in alginate beads at the constant dose of 1 l m−2) were tested. For all bacterial treatments the density of P. fluorescens BBc6R8 in the soil, determined by dilution plating, dropped below the detection limit (10−2 cfu g−1 DW soil) 2 weeks after inoculation. Fifteen weeks after inoculation, the introduced bacterium could be detected by enrichment only in the treatments inoculated with the highest bacterial dose. Two years after inoculation, P. fluorescens BBc6R8 could not be detected in the soil of any of the bacterial treatments. Five months after inoculation and sowing, bacterial inoculation significantly increased the percentage of mycorrhizal short roots on plants inoculated with either low or high amounts of L. bicolor, in one of the two nurseries. The lowest bacterial dose increased mycorrhizal colonization from 45 to 70% in plants inoculated with the low amount of fungal inoculum, and from 64 to 77% in plants inoculated with the high amount of fungal inoculum. The lowest bacterial dose increased mycorrhizal colonization more than the highest bacterial dose. The same L. bicolor mycorrhizal index (70%) was obtained with 50 mg m−2 DW mycelium plus the bacterium than with twice this fungal dose and no bacterium (64%). Two years after inoculation, the height of the mycorrhizal Douglas-firs in the other nursery was significantly increased by the lowest bacterial dose (from 40.7 to 42.6 cm). These results indicate that co-inoculating a helper bacterium together with an ectomycorrhizal fungus can be an efficient way of optimizing controlled mycorrhization techniques for the production of high-quality Douglas-fir planting stocks. They also confirm that BBc6R8 acts at a low population density (less than 102 cfu g−1 soil); this contrasts with most PGPR effects discussed in the literature, where the minimal inoculation dose of 105 cfu g−1 soil is required to obtain the beneficial effect.

Effect of plant nitrogen status on the contribution of arbuscular mycorrhizal hyphae to plant nitrogen uptake

Abstract: The contribution of hyphae of Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe (BEG 107) to the acquisition of mineral nitrogen by Triticum aestivum L. cv. Hano (wheat) was tested under conditions of low P and high N (+N−P) or low N (−N−P). Mycorrhizal colonisation increased the shoot dry weight and plant tissue concentrations of P and cations. However, N tissue concentrations of mycorrhizal plants were not increased, although nitrate reductase activities were significantly higher (in vivo activity) in +N−P mycorrhizal compared to non-mycorrhizal roots. Severe plant N deficiency reduced the percentage root length colonised (but not the percentage viable colonisation), hyphal length, total N uptake by hyphae and dry weight of mycorrhizal plants. Although mycorrhizal colonisation did not affect the overall plant N status, hyphae transported 1% (−N−P) and 7% (+N−P) of the N-labelled NH4NO3 to mycorrhizal plants over 48 h. The higher rate of hyphal N uptake was apparently related to the more extensive hyphal growth at the higher level of plant N supply. However, the hyphal N supply was not sufficiently high to sustain adequate N nutrition of the plants supplied with very low amounts of N to the roots. Conversely, a sufficient N supply to the roots was important for the development of an extensive mycelium.

Quantitative trait loci controlling vegetative growth rate in the edible basidiomycete Pleurotus ostreatus.

Abstract: Mycelium growth rate is a quantitative characteristic that exhibits continuous variation. This trait has applied interest, as growth rate is correlated with production yield and increased advantage against competitors. In this work, we studied growth rate variation in the edible basidiomycete Pleurotus ostreatus growing as monokaryotic or dikaryotic mycelium on Eger medium or on wheat straw. Our analysis resulted in identification of several genomic regions (quantitative trait loci [QTLs]) involved in the control of growth rate that can be mapped on the genetic linkage map of this fungus. In some cases monokaryotic and dikaryotic QTLs clustered at the same map position, indicating that there are principal genomic areas responsible for growth rate control. The availability of this linkage map of growth rate QTLs can help in the design of rational strain breeding programs based on genomic information.

Decomposition of red clover (Trifolium pratense) roots

Abstract: We have followed the decomposition of red clover root remains and described the process. In this investigation, red clover roots, divided into three diameter classes: 4 mm, were incubated in mesh bags in a loam soil at a temperature of 22°C and a moisture of pF 2–3 for up to 196 days. Analyses were made on the initial dead plant material and on mesh-bag contents of the 1–4 mm roots for the amounts of water and ethanol solubles, solid polysaccharides, lignin, ash, carbon, nitrogen and fungal mycelium. Organic matter mass loss was fast during the first 13 days (44%) and almost ceased after 30 days when about 29% of the organic material remained. There was no notable difference in mass- or nitrogen loss from roots of different diameters. The carbon-to-nitrogen ratio of the root remains decreased from initially 25–27 to 11–13 at the end of the incubation. The high rate of mass loss at the beginning is explained by the considerable initial concentration of water-soluble substances (31%), being the fraction which decreased the fastest (roots 1–4 mm φ). Glucans comprising 40% of the initial root material, were degraded linearly to total mass loss. Other polysaccharides (galactans, mannans, xylans, arabans and rhamnans) disappeared more slowly than the glucans. The amount of total fungal mycelium within the decomposing root remains increased during the incubation from 55 to 867m g −1 of organic material.

Isolation and characterization of new allosamidins.

Abstract: Three of new allosamidins, termed glucoallosamidins A (5), B (6) and methyl-N-demethyl-allosamidin (4), were isolated as yeast chitinase inhibitors from the mycelium of Streptomyces sp. SA-684.