Total Hyphae Research Articles

Root Traits and Mechanical Properties of Three Shrubland Species: Implications for Bioengineered Slope Stability

This study aimed to evaluate the ability of three shrubland species to consolidate slopes using root morphological traits and mechanical properties. The results showed that root tensile force increased and root tensile strength decreased with root diameter (from 0.3 to 5.5 mm) among all study species. Under the same level of root diameter, root tensile force and root tensile strength were highest for Amorpha fruticosa Linn. (AFL), followed by Swida alba Opiz (SAO) and lowest for Lespedeza bicolor Turcz (LBT). The mean branching ratio, root angle, stele to root diameter ratio, specific root length, individual length and surface area, and mean diameter of fine roots in different slopes were higher for AFL and SAO than for LBT, especially for high root orders (the third to fifth root orders). Furthermore, total hyphae length, total hyphae surface area, total hyphae volume, hyphae mean diameter, total glomalin-related soil proteins (GRSP), and easily extractable GRSP in different slopes also were highest for AFL, followed by SAO and lowest for LBT. However, root and mycelium traits had a positive effect on soil cohesion. These results suggested that root traits and mechanical properties of AFL and its impact on soil properties would enable more effective to consolidate slopes than SAO and LBT, revealing that planting AFL might be a better way for enhancing bioengineered slope stability in this study region.

Nitrogen deposition and decreased precipitation altered nutrient foraging strategies of three temperate trees by affecting root and mycorrhizal traits

Roots of nearly all plants have symbiotic relationships with mycorrhizal fungi. The root-mycorhizosphere serves an important role in both nutrient acquisition required for the plant growth, and soil carbon cycling of terrestrial ecosystems. The identification of root-mycorhizosphere traits that can be linked to nutrient acquisition is quite indispensable, especially for understanding and predicting plants nutrient acquisition strategies and ecosystem processes under climate change. Nonetheless, tree roots and mycorrhizal fungi traits variations are still rarely quantified synchronously in previous studies, which lead to an important knowledge gap in our understanding of how climate change will affect nutrient foraging strategies and soil carbon cycling. Thus, we conducted a decreased precipitation and N addition experiment to simulate climate change scenarios. Traits of root orders and mycorrhizal fungi that related to nutrient foraging were examined under different treatments across three coexisting mycorrhizal temperate tree species. N addition significantly increased individual root length, individual root surface area and mean root diameter in low root orders (the first root order or the first to third root orders), while it decreased or did not change these traits in high root orders (the fourth and fifth root orders). N addition tended to decrease branching intensity in all root orders across all species. Decreased precipitation significantly increased individual root length and individual root surface area of low order roots (the first and second root orders), while decreased or unchanged these traits in others root orders across all species. Specific root length was significantly increased in the first to fifth root orders with decreased precipitation and decreased in the second to fifth root orders with N addition (except Pinus koraiensis). Moreover, N addition significantly decreased total hyphae length, and significantly increased the mean hyphae diameter. Decreased precipitation significantly increased the total hyphae length and the total hyphae surface area compared with the control. Across all species, N addition, decreased precipitation and their interaction led to significantly decreased mycorrhizal colonization. The impacts of N addition and decreased precipitation on mycorrhizal fungi traits also were mediated by tree species. These results indicated that N addition and decreased precipitation significantly changed fine root and mycorrhizal morphological traits, which would alter the below-ground foraging strategies. These results indicate that the variation in root morphology by order under treatments suggests that roots at different branch order positions have different morphological structure and physiological functions. The trait patterns we found support the hypothesis that under climate change, plants attempt to improve resource acquisition.

Pinewood nematode infection alters root mycoflora ofPinus tabulaeformisCarr

This study investigates pinewood nematode's impacts on root mycoflora of Pinus tabulaeformis. The biomass, colonization rate, community structure and diversity of root-associated fungi were investigated in pinewood nematode-infected and nematode-noninfected P. tabulaeformis. The results indicated that the roots of P. tabulaeformis were colonized highly by root-associated fungi, mainly ectomycorrhizal fungi (ECMF) and dark septate endophytes. Infection of pinewood nematode was associated with a significant (P<0·05) decrease in root colonization rates by ECMF, dark septate endophytes and total hyphae, as well as in fungal biomass in the roots. Illumina MiSeq sequences of tagged amplicons of 18S rDNA region revealed Basidiomycota (65·70%) and Ascomycota (34·14%) as the dominant root-associated fungi in roots of P. tabulaeformis. Among the detected operational taxonomic units (OTUs), ECMF and dark septate endophytes exhibited a higher relative abundance in trees infected by pinewood nematode compared with noninfected ones. The infection of pinewood nematode altered the composition and OTU abundance of root-associated fungi community in P. tabulaeformis roots with a decrease in the biomass, species richness and diversity of root-associated fungi, as well as in the colonization rates and abundance of ECMF and dark septate endophytes. This study is an important contribution for better understanding the interaction between pine wilt disease and root-associated fungi.

High-efficiency extracellular release of free fatty acids from Aspergillus oryzae using non-ionic surfactants

Free fatty acids (FFAs) are useful for generating biofuel compounds and functional lipids. Microbes are increasingly exploited to produce FFAs via metabolic engineering. However, in many microorganisms, FFAs accumulate in the cytosol, and disrupting cells to extract them is energy intensive. Thus, a simple cost-effective extraction technique must be developed to remove this drawback. We found that FFAs were released from cells of the filamentous fungus Aspergillus oryzae with high efficiency when they were cultured or incubated with non-ionic surfactants such as Triton X-100. The surfactants did not reduce hyphal growth, even at 5% (w/v). When the faaA disruptant was cultured with 1% Triton X-100, more than 80% of the FFAs synthesized de novo were released. When the disruptant cells grown without surfactants were incubated for 1h in 1% Triton X-100 solution, more than 50% of the FFAs synthesized de novo were also released. Other non-ionic surfactants in the same ether series, such as Brij 58, IGEPAL CA-630, and Tergitol NP-40, elicited a similar FFA release. The dry cell weight of total hyphae decreased when grown with 1% Triton X-100. The decrement was 4.9-fold greater than the weight of the released FFAs, implying release of other intracellular compounds. Analysis of the culture supernatant showed that intracellular lactate dehydrogenase was also released, suggesting that FFAs are not released by a specific transporter. Therefore, ether-type non-ionic surfactants probably cause non-specific release of FFAs and other intracellular compounds by increasing cell membrane permeability.

Relative abundance and activity of melanized hyphae in different soil ecosystems

Here we report on the frequency of melanized fungal hyphae in 323 soils, covering different land use types. The proportion of total hyphae that was melanized averaged 61%. Arable fields with loamy sand, heathlands and city parks on sandy soils had the highest percentage of melanized hyphae. In addition to the frequency determinations, a microcosm study was performed on the role of melanized hyphae in two different ecosystems: an ex-arable field and a forest. Melanized hyphae appeared to be part of the active hyphae in the forest soil but not in the ex-arable soil. In conclusion, our results indicate that (1) melanized hyphae represent a large proportion of the total fungal biomass in soils and that (2) their function might differ between ecosystems.

Effects of arbuscular mycorrhizal fungi alkaline phosphatase activities on Hippophae rhamnoides drought-resistance under water stress conditions

The effects of arbuscular mycorrhizal fungi alkaline phosphatase (ALP) activities on the drought-resistance of Hippophaerhamnoides under water stress have been studied using histochemical techniques. The result shows in the mycorrhizae that total hyphae and functional hyphae form the base for the active hyphae, and amounts follow the order total hyphae>functional hyphae>active hyphae. Active hyphae play an important role in the biomass accumulation of the hosts; the hyphae with phosphatase activity (ALP) have a positive and strong effect on H. rhamnoides growth and its drought-resistance, and the rise of ALP is related to an increase in the fresh weight of the host trees, and a reduction of wilting. The direct participation of ALP in the P nutrient exchange host trees can improve the nutrient and water conditions, and raise their drought-resistance.

Vertical distribution of arbuscular mycorrhizal fungi under corn ( Zea mays L.) in no-till and conventional tillage systems

We compared the vertical distribution (0–25 cm) of arbuscular mycorrhizae, extraradical hyphae, and glomalean spores at grain-filling of corn under conventional tillage versus no tillage. Root colonization, total hyphae density, and spore density were correlated, and were highest at a depth of 0–15 cm in soil. Tillage significantly reduced total hypha density and spore density at 0–5 cm depth, but did not affect root colonization. Plowing below 15 cm is likely to diminish AM fungus inocula in the rooting zone of establishing seedlings.