Abstract:Non-native invasive species (NIS) release chemicals into the environment that are unique to the invaded communities, defined as novel chemicals. Novel chemicals impact competitors, soil microbial communities, mutualists, plant enemies, and soil nutrients differently than in the species' native range. Ecological functions of novel chemicals and differences in functions between the native and non-native ranges of NIS are of immense interest to ecologists. Novel chemicals can mediate different ecological, physiol… Show more
“…However, we could not rule out that other chemicals may also be able to enhance AM fungal growth and association with host plants. Moreover, many environmental factors such as temperature, nutrient availability, soil water and other microbes, and even plant neighbors, may also affect root exudation and chemicals as well as AM fungal growth (Badri & Vivanco, 2009; Yoneyama et al ., 2012; Kong et al ., 2018; de Vries et al ., 2019; Inderjit et al ., 2021). Furthermore, for plant invasion, selection may favor species that have high root exudation in nonnative ranges (Callaway & Ridenour, 2004), and escape from natural enemies (herbivores and pathogens) may alter plant chemical signals that are associated with root chemical exudates (Tian et al ., 2021).…”
Section: Discussionmentioning
confidence: 99%
“…In a meta-analysis of plant-AM fungi interactions, Bunn et al (2015) found that the strength of invasive plant-AM fungal mutualisms may depend on species and functional group. Although many studies have examined the difference in plant-AM fungal mutualism between native and invasive species (Reinhart & Callaway, 2006;Awaydul et al, 2019), the role that chemicals released by plants play is unclear (Inderjit et al, 2021).…”
Summary
Invasive plants can change soil properties resulting in improved growth. Although invaders are known to alter soil chemistry, it remains unclear if chemicals secreted by roots facilitate invasive plant–soil mutualisms.
With up to 19 confamilial pairs of invasive and native plants, and most of which were congeners, we explored the root exudate‐induced changes in plant–arbuscular mycorrhizal (AM) fungal mutualisms.
We found that, relative to natives, invaders had greater AM colonization, greater biomass and their root exudates contained higher concentrations of two common chemical signals – quercetin and strigolactones – which are known to stimulate AM fungal growth and root colonization. An exudate exchange experiment showed that root exudates from invaders increased AM colonization more than exudates from natives. However, application of activated carbon led to greater reduction in AM colonization and plant biomass for invaders than natives, suggesting stronger effects of chemical signals in root exudates from invaders.
We show that nonnative plants promote interactions with soil mutualists via enhancing root exudate chemicals, which could have important implications for invasion success.
“…However, we could not rule out that other chemicals may also be able to enhance AM fungal growth and association with host plants. Moreover, many environmental factors such as temperature, nutrient availability, soil water and other microbes, and even plant neighbors, may also affect root exudation and chemicals as well as AM fungal growth (Badri & Vivanco, 2009; Yoneyama et al ., 2012; Kong et al ., 2018; de Vries et al ., 2019; Inderjit et al ., 2021). Furthermore, for plant invasion, selection may favor species that have high root exudation in nonnative ranges (Callaway & Ridenour, 2004), and escape from natural enemies (herbivores and pathogens) may alter plant chemical signals that are associated with root chemical exudates (Tian et al ., 2021).…”
Section: Discussionmentioning
confidence: 99%
“…In a meta-analysis of plant-AM fungi interactions, Bunn et al (2015) found that the strength of invasive plant-AM fungal mutualisms may depend on species and functional group. Although many studies have examined the difference in plant-AM fungal mutualism between native and invasive species (Reinhart & Callaway, 2006;Awaydul et al, 2019), the role that chemicals released by plants play is unclear (Inderjit et al, 2021).…”
Summary
Invasive plants can change soil properties resulting in improved growth. Although invaders are known to alter soil chemistry, it remains unclear if chemicals secreted by roots facilitate invasive plant–soil mutualisms.
With up to 19 confamilial pairs of invasive and native plants, and most of which were congeners, we explored the root exudate‐induced changes in plant–arbuscular mycorrhizal (AM) fungal mutualisms.
We found that, relative to natives, invaders had greater AM colonization, greater biomass and their root exudates contained higher concentrations of two common chemical signals – quercetin and strigolactones – which are known to stimulate AM fungal growth and root colonization. An exudate exchange experiment showed that root exudates from invaders increased AM colonization more than exudates from natives. However, application of activated carbon led to greater reduction in AM colonization and plant biomass for invaders than natives, suggesting stronger effects of chemical signals in root exudates from invaders.
We show that nonnative plants promote interactions with soil mutualists via enhancing root exudate chemicals, which could have important implications for invasion success.
“…Second, native and invasive plants grown in soil containing heterogeneous forms of P may differ in their plasticity to adjust root architecture and allocation (Yang et al, 2020;Zhang et al, 2022), which both govern interactions with AMF (Bergmann et al, 2020). Third, invasive species may also release greater concentrations of root chemical signaling compounds, such as flavonoids and strigolactones than native species, enhancing communications with mycorrhizal fungi (Inderjit et al, 2021;.…”
Section: Variations In Plant-amf Interactions Induced By Soil P Formsmentioning
Interactions between plants and arbuscular mycorrhizal fungi (AMF) are strongly affected by soil phosphorus (P) availability. However, how P forms impact rhizosphere AMF diversity, community composition, and the co-occurrence network associated with native and invasive plants, and whether these changes in turn influence the invasiveness of alien species remain unclear. In this work, we performed a greenhouse experiment with the invasive species Solidago canadensis and its native congener S. decurrens to investigate how different forms of P altered the AMF community and evaluate how these changes were linked with the growth advantage of S. canadensis relative to S. decurrens. Plants were subjected to five different P treatments: no P addition (control), simple inorganic P (sodium dihydrogen phosphate, NaP), complex inorganic P (hydroxyapatite, CaP), simple organic P (adenosine monophosphate, AMP) and complex organic P (myo-inositol hexakisphosphate, PA). Overall, invasive S. canadensis grew larger than native S. decurrens across all P treatments, and this growth advantage was strengthened when these species were grown in CaP and AMP treatments. The two Solidago species harbored divergent AMF communities, and soil P treatments significantly shifted AMF community composition. In particular, the differences in AMF diversity, community composition, topological features and keystone taxa of the co-occurrence networks between S. canadensis and S. decurrens were amplified when the dominant form of soil P was altered. Despite significant correlations between AMF alpha diversity, community structure, co-occurrence network composition and plant performance, we found that alpha diversity and keystone taxa of the AMF co-occurrence networks were the primary factors influencing plant growth and the growth advantage of invasive S. canadensis between soil P treatments. These results suggest that AMF could confer invasive plants with greater advantages over native congeners, depending on the forms of P in the soil, and emphasize the important roles of multiple AMF traits in plant invasion.
“…Root exudates are crucial for signaling between AM fungi and plants to initiate the symbiosis (Harrison, 2005) so this finding provides an important clue. Root exudates have been highlighted in invasion biology for other reasons, including allelopathy, perhaps contributing to the suppression of native plants and soil biota, including AM fungi (Inderjit et al ., 2021). An underlying mechanism for allelopathy‐driven impacts might be the biogeographic novelty of the chemicals, in that species that are evolutionarily naïve to certain biochemicals can be particularly vulnerable to them.…”
mentioning
confidence: 99%
“…show that: (1) exotic plant species invest more in producing and sending chemical signals to AM fungi than do native plants; (2) signals produced by nonnative plants are more effective at recruiting AM fungi to exotic plant roots than signals produced by native species, and most importantly; (3) recruiting more AM fungi corresponds with greater plant growth. Exotic invasive plant species out‐perform natives in many ways (Inderjit et al ., 2021), but if and how mutualism is involved in this superior performance remains an ecological frontier.‘Do mutualisms become less beneficial over time to limit costs, and is there something about novelty, per se, in mutualistic relationships that we do not fully understand?’…”
Why are so many exotic plant species more abundant and have greater impacts in their nonnative than native ranges? Hypotheses that address this vexing question generally focus on variation in the intensity of negative interactions, such as escaping consumers or outcompeting natives in nonnative ranges (Jeschke, 2014). But in addition to these, some invasive species have shown a remarkable ability to capitalize on generalist mutualists in their nonnative ranges (Traveset & Richardson, 2014), and in some cases procure more or better mutualists than in their native ranges. This latter phenomenon was formalized as the Enhanced Mutualism Hypothesis (EMH; Reinhart & Callaway, 2004, 2006. In this issue of New Phytologist, Yu et al. (2022, pp. 1140-1153) 'Greater chemical signaling in root exudates enhances soil mutualistic associations in invasive plants compared to natives' show that interactions with arbuscular mycorrhizal (AM) fungi are more beneficial for exotic invasive species than related native species. This provides some of the most convincing support of the EMH to date. With an elegant set of experiments, Yu et al. show that: (1) exotic plant species invest more in producing and sending chemical signals to AM fungi than do native plants; (2) signals produced by nonnative plants are more effective at recruiting AM fungi to exotic plant roots than signals produced by native species, and most importantly; (3) recruiting more AM fungi corresponds with greater plant growth. Exotic invasive plant species out-perform natives in many ways (Inderjit et al., 2021), but if and how mutualism is involved in this superior performance remains an ecological frontier.
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