Can arbuscular mycorrhizal fungi from non-invaded montane ecosystems facilitate the growth of alien trees?

Does the flavonoid quercetin influence the generalist-selective nature of mycorrhizal interactions in invasive and non-invasive native woody plants?

It has been suggested that invasive plant species are more generalist than non-invasive species in their interactions with arbuscular mycorrhizal fungi (AMF), allowing them to associate with novel AMF communities. There is emerging evidence suggesting that the flavonoid quercetin may play a role in regulating these interactions as a signaling compound. In this study, we experimentally grew three invasive alien and three non-invasive native woody species with AMF communities collected from within (though foreign to invasives) and outside their current distribution ranges. After 96 days, we: (a) assessed mycorrhizal colonization rates; (b) evaluated the impact of these interactions on plant performance (growth and phosphorus nutrition); and (c) tested whether these responses were influenced by the addition of quercetin to the plant growth medium. Our findings reveal that the invasive species exhibited mycorrhizal colonization when grown with both novel AMF communities and benefited from them in terms of phosphorus (P) nutrition. In contrast, two of the three non- invasive native species showed mycorrhizal colonization and enhanced P nutrition only with AMF from their current distribution range, but not with novel AMF from outside their range, suggesting selective behavior in their mycorrhizal interactions. The addition of quercetin did not have a strong effect on mycorrhizal colonization in either invasive or non-invasive native species. However, quercetin promoted moderate increases in P nutrition in the two non-invasive native species when grown with the novel AMF communities. Overall, the results suggest that invasive species are more generalist in their AM symbiosis than two of the three non-invasive species, and that the addition of quercetin had a limited, moderate influence on their AM interactions.

A review of botany, phytochemistry, pharmacology, and applications of the herb with the homology of medicine and food: Ligustrum lucidum W.T. Aiton

Ligustrum lucidum W.T. Aiton is an outstanding herb with the homology of medicine and food. Its ripe fruits are traditionally used as an important tonic for kidneys and liver in China. Ligustrum lucidum W.T. Aiton is rich in nutritional components and a variety of bioactive ingredients. A total of 206 compounds have been isolated and identified, they mainly include flavonoids, phenylpropanoids, iridoid glycosides, and triterpenoids. These compounds exert anti-osteoporosis, anti-tumor, liver protective, antioxidant, anti-inflammatory, and immunomodulatory effects. Ligustrum lucidum W.T. Aiton has been traditionally used to treat many complex diseases, including osteoporotic bone pain, rheumatic bone, cancer, related aging symptoms, and so on. In the 2020 Edition of Chinese Pharmacopoeia, there are more than 100 prescriptions containing L. lucidum W.T. Aiton. Among them, some classical preparations including Er Zhi Wan and Zhenqi fuzheng formula, are used in the treatment of various cancers with good therapeutic effects. Additionally, L. lucidum W.T. Aiton has also many excellent applications for functional food, ornamental plants, bioindicator of air pollution, algicidal agents, and feed additives. Ligustrum lucidum W.T. Aiton has rich plant resources. However, the application potential of it has not been fully exploited. We hope that this paper provides a theoretical basis for the high-value and high-connotation development of L. lucidum W.T. Aiton in the future.

The Invasion of Galinsoga quadriradiata into High Elevations Is Shaped by Variation in AMF Communities

Mountain ranges have been previously suggested to act as natural barriers to plant invasion due to extreme environmental conditions. However, how arbuscular mycorrhizal fungi (AMF) affect invasion into these systems has been less explored. Here, we investigated how changes in AMF communities affect the performance of Galinsoga quadriradiata in mountain ranges. We performed a greenhouse experiment to study the impact of inoculations of AMF from different elevations on the performance and reproduction of invaders and how competition with native plants changes the effects of invader-AMF interactions. We found strong evidence for a nuanced role of AMF associations in the invasion trajectory of G. quadriradiata, with facilitative effects at low elevations and inhibitory effects at high elevations. Galinsoga quadriradiata performed best when grown with inoculum collected from the same elevation but performed worst when grown with inoculum collected from beyond its currently invaded range, suggesting that AMF communities can help deter invasion at high elevations. Finally, the invasive plants grown alone experienced negative effects from AMF, while those grown in competition experienced positive effects, regardless of the AMF source. This suggests that G. quadriradiata lowers its partnerships with AMF in stressful environments unless native plants are present, in which case it overpowers native plants to obtain AMF support during invasion. Finally, our results indicate that invader-AMF interactions can inhibit invasive range expansion at high elevations, and biotic interactions, in addition to harsh environmental conditions, make high-elevation mountain ranges natural barriers against continued invasion.

Reproductive Ecology of the Invasive Alien Shrub Pyracantha angustifolia in the Grassland Biome, South Africa

Knowledge on reproductive traits of problematic invasive alien plants, such as the woody invasive shrub Pyracantha angustifolia of temperate Chinese origin, can help better manage invasive species. To determine factors contributing to its invasion, we investigated floral visitors and pollen loads, self-compatibility, seed set, seed rain, soil seed banks, and seed longevity in the soil. Generalist insects were recorded visiting flowers and all carried pollen loads of high purity (>70%). Floral visitor exclusion experiments showed that P. angustifolia can set seed (66%) without pollen vectors, although natural pollination resulted in higher fruit set (91%). Fruit count surveys and seed set showed an exponentially increased relationship between seed set and plant size with high natural seed yield (±2 million seeds m^-2). Soil core samples revealed a high seed density of 46,400 ± (SE) 8934 m^-2 under shrubs, decreasing with distance away from the shrub. Bowl traps stationed under trees and fences confirmed that seeds were efficiently dispersed by animals. Buried seeds survived for less than six months in the soil. Due to high seed production, self-compatibility augmented by generalist pollen vectors, and effective seed dispersal by local frugivores, it is difficult to manage the spread manually. Management of this species should focus on the short life span of seeds.

Fungi Present in the Organic and Mineral Layers of Six Broad-Leaved Tree Plantations as Assessed by the Plate Dilution Method

This study examined the distribution of culturable fungi and predominant genera in the organic layer and in the upper layers of the mineral soil of six broad-leaved tree plantations in autumn, after the full fall of leaves. In total, 1335 fungal isolates were recovered from an organic layer and two mineral layers (0–4 cm and 5–8 cm) of soil. The structure of fungal genera differed in the tree plantations and in the three studied soil layers. The organic layer was the layer most populated by fungi compared to the mineral layers. In the organic layer, Penicillium and phyllosphere fungi such as Cladosporium and Phoma dominated. Deeper in the soil, the dominance of certain genera decreased with the increase in Trichoderma, Mucor, Mortierella, and entomopathogenic fungi such as Paecilomyces and Beauveria. Penicillium was one of the most abundant fungi in all soil layers studied.

Enrichment of nosZ-type denitrifiers by arbuscular mycorrhizal fungi mitigates N2 O emissions from soybean stubbles

Hotspots of N2 O emissions are generated from legume residues during decomposition. Arbuscular mycorrhizal fungi (AMF) from co-cultivated intercropped plants may proliferate into the microsites and interact with soil microbes to reduce N2 O emissions. Yet, the mechanisms by which or how mycorrhizal hyphae affect nitrifiers and denitrifiers in the legume residues remain ambiguous. Here, a split-microcosm experiment was conducted to assess hyphae of Rhizophagus aggregatus from neighbouring maize on overall N2 O emissions from stubbles of nodulated or non-nodulated soybean. Soil microbes from fields intercropped with maize/soybean amended with fertilizer nitrogen (SS-N1) or unamended (SS-N0) were added to the soybean chamber only. AMF hyphae consistently reduced N2 O emissions by 20.8%-61.5%. Generally, AMF hyphae promoted the abundance of N2 O-consuming (nosZ-type) denitrifiers and altered their community composition. The effects were partly associated with increasing MBC and DOC. By contrast, AMF reduced the abundance of nirK-type denitrifiers in the nodulated SS-N0 treatment only and that of AOB in the non-nodulated SS-N1 treatment. Taken together, our results show that AMF reduced N2 O emissions from soybean stubbles, mainly through the promotion of N2 O-consuming denitrifiers. This holds promise for mitigating N2 O emissions by manipulating the efficacious AMF and their associated microbes in cereal/legume intercropping systems.

Economic impact of invasive alien species in Argentina: a first national synthesis

Invasive alien species (IAS) affect natural ecosystems and services fundamental to human well-being, human health and economies. However, the economic costs associated with IAS have been less studied than other impacts. This information can be particularly important for developing countries such as Argentina, where monetary resources for invasion management are scarce and economic costs are more impactful. The present study provides the first analysis of the economic cost of IAS in Argentina at the national level, using the InvaCost database (expanded with new data sources in Spanish), the first global compilation of the reported economic costs of invasions. We analyzed the temporal development of invasions costs, distinguishing costs according to the method reliability (i.e. reproducibility of the estimation methodology) and describing the economic costs of invasions by invaded environment, cost type, activity sector affected and taxonomic group of IAS. The total economic cost of IAS in Argentina between 1995 and 2019 was estimated at US$ 6,908 million. All costs were incurred and 93% were highly reliable. The recorded costs were mainly related to terrestrial environments and the agricultural sector, with lack of costs in other sectors, making it difficult to discuss the actual distribution of invasion costs in Argentina. Nevertheless, the reported costs of IAS in this country are very high and yet likely much underestimated due to important data gaps and biases in the literature. Considering that Argentina has an underdeveloped economy, costs associated with biological invasions should be taken into consideration for preventing invasions, and to achieve a more effective use of available resources.

Functional niche differences between native and invasive tree species from the southern Brazilian mixed forest

Biological invasion is a major threat to global biodiversity and ecosystem services. We examined the functional traits similarity between a set of native and non-native invasive tree species from the Southern Brazilian subtropical mixed forest, part of an important global hotspot for biodiversity conservation. We hypothesized that invasive species occupy marginal niche spaces. We ordered the species using the Principal Component Analysis based on their wood density, leaf area, and specific leaf area. These are all important traits that summarize essential ecological strategies associated with resource acquisition and conservation. Functional overlaps between non-native and native species were analyzed through kernel density estimation of continuous traits data. While native and non-native invasive species were distributed along the same functional gradients, the position of non-native species in the functional space is species and traits specific. We concluded that within Brazilian subtropical mixed forests, the functional dissimilarity as a key factor in invasion success could not be generalized for all species and traits.

A Global Review of Ligustrum Lucidum (OLEACEAE) Invasion

Ligustrum lucidum is a highly invasive East Asian tree that successfully colonizes several subtropical and temperate areas around the world. Its invasion capacity results from a widespread human use mostly in urban and periurban settings, very abundant fruit and seed production, small bird-dispersed fruits, high germination rates, resprouting capacity, fast growth rates, low herbivory levels and tolerance to a wide range of light, temperature and soil. All these traits contribute to its ability to rapidly increase in abundance, alter biodiversity, landscape ecology and limit its management. This paper reviews the current knowledge on L. lucidum with particular focus on its uses, distribution, invasiveness, ecological and economic impacts and control measures. Most relevant aspect of the review highlight the negative ecological impacts of L. lucidum, its potential to continue expanding its range of distribution and the need of further studies on the eco-physiology of the species, economic impact and social perception of its invasion and early warning systems.

Insights from invasion ecology: Can consideration of eco-evolutionary experience promote benefits from root mutualisms in plant production?

Mutualistic plant-microbial functioning relies on co-adapted symbiotic partners as well as conducive environmental conditions. Choosing particular plant genotypes for domestication and subsequent cultivar selection can narrow the gene pools of crop plants to a degree that they are no longer able to benefit from microbial mutualists. Elevated mineral nutrient levels in cultivated soils also reduce the dependence of crops on nutritional support by mutualists such as mycorrhizal fungi and rhizobia. Thus, current ways of crop production are predestined to compromise the propagation and function of microbial symbionts, limiting their long-term benefits for plant yield stability. The influence of mutualists on non-native plant establishment and spread, i.e. biological invasions, provides an unexplored analogue to contemporary crop production that accounts for mutualistic services from symbionts like rhizobia and mycorrhizae. The historical exposure of organisms to biotic interactions over evolutionary timescales, or so-called eco-evolutionary experience (EEE), has been used to explain the success of such invasions. In this paper, we stress that consideration of the EEE concept can shed light on how to overcome the loss of microbial mutualist functions following crop domestication and breeding. We propose specific experimental approaches to utilize the wild ancestors of crops to determine whether crop domestication compromised the benefits derived from root microbial symbioses or not. This can predict the potential for success of mutualistic symbiosis manipulation in modern crops and the maintenance of effective microbial mutualisms over the long term.