Mycorrhiza最新文献

Early stages of the ectomycorrhizal symbiosis have rarely been studied on seedlings germinating in the field. By collecting lodgepole and ponderosa pine seedlings during their first growing season in recent clearcuts and burned areas, we were able to identify when colonization of pine roots first began, the rate at which ectomycorrhizal fungi colonized new germinants, and how this related to nitrogen nutrition and growth. Pine seedlings were first colonized in July, a month after germination was first observed. As the first seedlings became mycorrhizal, ectomycorrhizal lodgepole pine seedlings contained approximately 40% more nitrogen and > 60% greater biomass compared to uncolonized seedlings collected at the same time. Nitrogen content was 47% higher in mycorrhizal than nonmycorrhizal naturally-regenerating ponderosa pine seedlings. Ascomycetes, with a Pustularia sp. and Wilcoxina spp. most abundant, formed 80% of the ectomycorrhizae. Because all collected seedlings had ectomycorrhizae present on their roots by the end of the season, we concluded that inoculum of ectomycorrhizal fungi, especially of ruderal ascomycetes, was not limiting colonization of seedlings on these severely burned or recently clearcut sites. Our results are consistent with a role for ectomycorrhizal fungi in nitrogen acquisition, even within the first weeks after mycorrhiza formation; however, it is also possible that larger, more nitrogen-replete seedlings became colonized earlier than smaller seedlings. We saw no evidence of nitrogen loss by mycorrhizal pine seedlings as observed in previous studies.

Pedunculate oak (Quercus robur L.), a long-lived forest tree species, forms symbiotic relationships with ectomycorrhizal (ECM) fungi, which can promote nutrient uptake, stress resilience, and growth. Like other tropical and temperate tree species, pedunculate oak exhibits endogenous rhythmic growth (ERG), a trait conferring the ability to repeatedly alternate root and shoot flushes as well as growth cessation as response to changing environmental conditions. However, the effects of different ECM fungal species on the ERG dynamics remain largely unknown. Here, we investigated the impact of two ECM fungi-Piloderma croceum, a basidiomycete previously shown to promote growth while not found in natural oak stands, and Cenococcum geophilum, an oak-native ascomycete with broad ecological range-on growth performance, biomass partitioning, and ERG patterns in a clonal oak system (clone DF159). By combining in vitro experiments with Bayesian modelling, we show that P. croceum promotes tree growth among treatments, without disrupting the endogenous growth rhythm. In contrast, C. geophilum, while showing high mycorrhization rates, led to reduced biomass accumulation and altered developmental progression through the ERG stages, especially by prolonging the steady state development stage-part of the root flush and characterized by peak net carbon assimilation. Co-inoculation revealed a competitive advantage of C. geophilum in root colonization, yet growth responses resembled those of the control. Our findings demonstrate that ECM species exert species-specific effects on biomass production and temporal development of plants, underscoring the functional importance of ECM fungi in shaping host development. Assessing these interactions provides new insights into the functional diversity of ectomycorrhizal symbiosis and can inform forest management strategies aimed at enhanced resilience in oak-dominated ecosystems under rapidly changing climatic conditions.

Fully mycoheterotrophic orchids rely entirely on fungal symbionts for carbon acquisition and are often highly specialized in their fungal associations. Danxiaorchis yangii is a fully mycoheterotrophic orchid species with an extremely limited population in its endemic region of southeastern China. Its fungal symbionts remain poorly understood. In this study, we investigated the fungal associations of D. yangii using both the isolation of culturable fungal endophytes and high-throughput sequencing of the ribosomal internal transcribed spacer-1 (ITS1) region. Six strains of Psathyrellaceae were isolated from rhizomes (underground stems) of D. yangii and phylogenetic analysis revealed that they belong to two main taxa. High-throughput sequencing further confirmed that the fungal community within the rhizomes was dominated by Psathyrellaceae. Moreover, an in vitro symbiotic seed germination assay demonstrated that one of the isolated strains could promote the growth of germinating seeds to the protocorm stage. These findings are significant for advancing our understanding of the mycoheterotrophic symbiosis in D. yangii.

Plants face persistent biotic pressures from pathogens and herbivores, necessitating effective defense mechanisms. Common mycorrhizal networks (CMNs), formed by arbuscular mycorrhizal fungi, facilitate inter-plant defense signal transmission. However, little is known about interspecies signal transmission through CMNs. This study aimed to investigate whether defense signals can be transferred from pathogen-infected white clover (Trifolium repens) to neighboring healthy perennial ryegrass (Lolium perenne) via CMNs and to assess the subsequent activation of disease-resistance responses in ryegrass at the transcriptional level. A dual-chamber experimental setup was used, in which white clover served as the donor plant and perennial ryegrass was the receiver plant. The results showed that pathogen-induced defense signals can be transferred from infected donor clover to healthy ryegrass plants through CMNs, inducing the expression of resistance genes in the neighboring plants, especially TRINITY_DN52759_c0_g1 (disease resistance protein RGA2). Importantly, the upregulated expression of defense genes was closely related to CAT activity. These factors enhance the defense response of neighboring healthy plants against potential pathogens. Although the pathogenic microbe evaluated is non-pathogenic to ryegrass, the signal transmission mechanism may apply to scenarios with shared threats. In addition, we identified gene modules significantly associated with CAT through weighted gene co-expression network analysis and screened key network genes (TRINITY_DN29267_c0_g1, TRINITY_DN37961_c0_g1, TRINITY_DN74958_c0_g2, TRINITY_DN7515_c0_g1, TRINITY_DN7587_c0_g6) in co-expression networks, which potentially play critical roles in defense responses. The findings suggest that CMNs serve as vital conduits for interplant defense signal transfer, facilitating early warning and defense activation against potential pathogens.

The regulation of cellular protein homeostasis involves the ubiquitin-proteasome system (UPS) by selectively targeting misfolded or end-of-life proteins. The involvement of the UPS in biotic stresses has been studied mainly in plant-pathogen interactions and poorly in plant-mutualistic interactions. Here, we studied through proteomic approaches (western blot, pull-down of polyubiquinated proteins and nano-LC-MS-MS analysis), the involvement of the UPS during the establishment of the mutualistic interaction between the arbuscular mycorrhizal fungus Rhizophagus irregularis DAOM197198 and the roots of Medicago truncatula, as well as in the established symbiosis. Roots of M. truncatula seedlings were harvested 0 h, 3 h, 6 h, 9 h, 12 h, 24 h and 15 days post-inoculation. We characterized a short-time and a-long-time response of the root ubiquitinome. Some proteins as such as flotilins or involved in the translational machinery were less-ubiquitinated, suggesting the facilitation of the de novo synthesis of proteins required to the establishment of arbuscular mycorrhizal symbiosis. In contrast, other proteins as transporters involved in plant nutrition through the direct pathway (i.e., MtPT5) and some enzymes involved in the lipid biosynthesis pathways were more-ubiquitinated, highlighting their putative degradation. In addition, Cdc48 protein accumulates in roots from 9 to 24 h post-inoculation, suggesting a role of Cdc48 in the transitory immune response during plant-fungal interactions. The activity of the UPS is consequently central in the establishment and functioning of arbuscular mycorrhizal symbiosis by modulating protein ubiquitination.

Ectomycorrhizal fungi (EMF) colonize roots to establish symbiotic associations with plants. Sporocarps of the EMF Tuber spp. are considered as a delicacy in numerous countries and is a kind of EMF of great economic and social importance. Elucidating host responses to Tuber colonization would facilitate the exploration of symbiotic interactions and contribute to truffle cultivation. Tuber indicum and T. panzhihuanense, two primary commercial truffle species in China, were selected to colonize Pinus armandii and Carya illinoinensis in a two-and-a-half-year symbiosis experiment. Host performances, including growth, nutrient uptake, and physiological characteristics, were dynamically monitored. The molecular response of host leaf to Tuber symbiosis was further analyzed using RNA-seq. Tuber indicum and T. panzhihuanense exhibited superior colonization of P. armandii compared to that of C. illinoinensis. Both Tuber species enhanced the performance of the two hosts by increasing their height, stem circumference, and biomass. Phosphorus levels and activities of peroxidase and catalase in hosts were observed to increase during Tuber symbiosis. The results confirmed that Tuber colonization led to significant alterations in leaf transcriptomic profiles of the two trees. Tuber indicum and T. panzhihuanense both elicited defense-related regulation in host leaves, such as secondary metabolism, cell wall biogenesis, plant hormone signal transduction, and plant-pathogen interaction, with distinct patterns in P. armandii and C. illinoinensis. Our study provides an evaluation of host performance during truffle symbiosis and highlights the diverse patterns of Tuber-induced systematic defense regulation in hosts, offering insights into the specific symbiotic traits of Tuber-host pairs.

This study explores the arbuscular mycorrhizal (AM) fungi associations of Agave tequilana, an emerging crop with significant commercial potential that is increasingly being grown outside its native distribution in the arid regions of the Americas. A greenhouse experiment was conducted using field-collected soil inoculum from various locations in South Australia to inoculate A. tequilana plus Plantago lanceolata as a comparative model host. Metagenomic sequencing of the colonized roots with AM fungal-specific amplicons assessed the AM fungal community structure. The Shannon alpha diversity was similar between both plant species, and both predominantly associated with the genus Glomus. However, A. tequilana had a narrower AM fungal community compared to P. lanceolata, which was associated with a broader diversity of AM fungi. Beta diversity analysis of the AM fungal community composition revealed that the factor species (agave/plantago) was significant (p = 0.0001), whereas the inoculum location was not (p = 0.29). The association of A. tequilana with AM fungi from the family Acaulosporaceae, as found in Mexican studies, could not be confirmed. These findings suggest a specialized adaptation of A. tequilana to specific AM fungal species, which could have important implications for using AM fungi in sustainable agave production when cultivated outside their native regions.

Ericoid mycorrhizal (ErM) fungi (ErMF) are crucial for the establishment of thousands of ericaceous species in heathlands and wetlands by increasing their tolerance to harsh conditions and improving nutrient uptake. However, ErM research has largely focused on a limited number of host species and four ErMF species (especially Hyaloscypha hepaticicola and Oidiodendron maius, to a lesser extent H. bicolor/H. finlandica and H. variabilis). Therefore, the degree to which other ericaceous plants and ErMF form functional associations, and corresponding benefits for plant growth, are not well understood. As such, we lack a clear understanding of how changes in fungal partners may influence plant fitness. To address this gap, we conducted a greenhouse experiment with nine ericaceous plant species and eight ErMF isolates to expand baseline knowledge regarding the effects of the ErM symbiosis on host plant growth. By analyzing ErM root colonization and host plant growth response, we observed that the mycorrhizal growth response (MGR) was variable and depended on plant and fungal identity. Moreover, overall inoculation effects on plant growth were independent from colonization levels. Finally, we found evidence that MGR was influenced by plant phylogeny. These results expand our basic understanding of the ErM symbiosis and provide valuable information for future restoration and conservation efforts.

Shorea robusta (Sal) is an ecologically and economically important hardwood tree species growing in the plains and lower foothills of the Himalayan region. It is a dual-mycorrhizal tree associated with both arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi. To understand how ECM communities associated with Sal roots are structured, we studied their diversity, composition, and root colonisation in four tropical forests along an elevation gradient (82 to 950 m a.s.l.). The ECM community was not found to be very diverse: we obtained 155 ECM operational taxonomic units (OTUs) belonging to 13 ECM genera in 8 families of Basidiomycota. The genus Tomentella was the most dominant, followed by Russula and Inocybe. Elevation explained 10.2% of variability in ECM composition, and significant effects of forest type, geographic position, soil temperature and moisture were confirmed. The forest at the highest elevation had ECM communities whose community structure was divergent from those at lower elevation. ECM root colonisation significantly decreased with increasing elevation and decreasing available P content. Whereas a low number of ECM species produced a high ECM colonisation of Shorea roots in low-elevation forests, a more diverse ECM community formed a low ECM colonization in high-elevation forests. The identified dominant species may be potentially used as inoculum for Sal forest restoration.

The recovery of the soil ecosystem after severe disturbances, such as coal-mining activities, depends on both abiotic and biotic improvements. This study assessed the influence of arbuscular mycorrhizal (AM) fungal consortia on microbial community dynamics across two stages of soil recovery - 2 years (2Y) and 15 years (15Y) post-disturbance - using a secondary succession forest (SSR) as a reference. We analyzed bacterial community composition via 16 S rRNA gene amplicon sequencing and evaluated key soil quality indicators. While inoculation with AM fungal consortia had minimal effects on most soil parameters, significant differences were observed between recovery stages. The 15Y recovery site exhibited improved soil structure, microbial activity, and aggregate stability compared to the 2Y site, highlighting the importance of long-term restoration. However, potential overlap in ecological roles among native microorganisms likely mitigates the impact of AMF inoculation. These findings suggest that AM fungal consortia alone may not drive immediate improvements in soil quality but can contribute to microbial interactions and recovery processes over time. This study highlights the complexity of soil restoration and emphasizes the need for strategies that integrate plant cover with microbial community development to enhance long-term ecosystem stability. Further research should explore the specific roles of AM fungi and native soil microbes in promoting soil structure and accelerating recovery.