Increasing flavonoid concentrations in root exudates enhance associations between arbuscular mycorrhizal fungi and an invasive plant

Abstract

Many invasive plants have enhanced mutualistic arbuscular mycorrhizal (AM) fungal associations, however, mechanisms underlying differences in AM fungal associations between introduced and native populations of invasive plants have not been explored. Here we test the hypothesis that variation in root exudate chemicals in invasive populations affects AM fungal colonization and then impacts plant performance. We examined flavonoids (quercetin and quercitrin) in root exudates of native and introduced populations of the invasive plant Triadica sebifera and tested their effects on AM fungi and plant performance. We found that plants from introduced populations had higher concentrations of quercetin in root exudates, greater AM fungal colonization and higher biomass. Applying root exudates more strongly increased AM fungal colonization of target plants and AM fungal spore germination when exudate donors were from introduced populations. The role of root exudate chemicals was further confirmed by decreased AM fungal colonization when activated charcoal was added into soil. Moreover, addition of quercetin into soil increased AM fungal colonization, indicating quercetin might be a key chemical signal stimulating AM fungal associations. Together these results suggest genetic differences in root exudate flavonoids play an important role in enhancing AM fungal associations and invasive plants’ performance, thus considering root exudate chemicals is critical to unveiling mechanisms governing shifting plant-soil microbe interactions during plant invasions.

The Role of Flavonoids in Invasion Strategy of Solidago canadensis L.

“…Recent studies have shown that content of quercetin is high in root exudates of invasive plants Triadica sebifera (L.) Small. The substance, as a part of exudates, is key in signaling for the interaction of plants with mycorrhizal fungi and soil microorganisms in general [ 62 ].…”

Novel chemicals engender myriad invasion mechanisms

“…In another study, Li et al (2020) found that invasive populations of C. odorata produced greater quantities of phenolic compounds; some of these phenolic compounds confer stronger defence and others may suppress native species (Table 1). Recently, Tian et al (2021) recorded more quercetin, a flavonoid, in root exudates of 60-or 90-day old Triadica sebifera plants from the non-native (USA) than from the native (China) range. Quercetin causes higher colonization by arbuscular mycorrhizal fungi of invasive populations of T. sebifera than of its native populations (Fig.…”

“…Root exudates contain quercetin Root exudates facilitate greater mycorrhizal colonisation of T. sebifera in the non-native range than in the native range (Tian et al, 2021) a Native vs non-native ranges.…”

“…Recently, Tian et al . (2021) recorded more quercetin, a flavonoid, in root exudates of 60‐d‐old or 90‐d‐old Triadica sebifera plants from the non‐native (USA) than from the native (China) range. Quercetin causes higher colonisation by arbuscular mycorrhizal fungi (AMF) of invasive populations of T .…”

From Microns to Meters: Exploring Advances in Legume Microbiome Diversity for Agroecosystem Benefits

“…For example, Medicago truncatula mutants unable to establish AMF symbiosis grown in field soil under greenhouse conditions had reduced microbial abundance in the rhizosphere, suggesting a role for conserved symbiotic pathways in rhizosphere enrichment processes (Wang et al, 2021). Although flavonoids are present across the plant kingdom (e.g., Lapcik et al, 2006;Tian et al, 2021), accumulated evidence suggests they are particularly prevalent among legumes (Veitch, 2007;Jasiński et al, 2009) and their importance in multiple initiation and regulatory functions pertaining to intracellular symbiosis cannot be understated. While there is limited research on differences in flavonoid profiles among legumes and non-legumes, Weston and Mathesius (2013) note that species-specific differences in root flavonoid exudation could be responsible for various rootmicrobe interactions.…”