Changes in arbuscular mycorrhizal fungal communities, mycorrhizal soil infectivity, and phosphorus availability under Chromolaena odorata (Asteraceae) invasions in a West-African forest-savanna ecotone.

Substantial areas of agricultural lands in Sub-Saharan Africa have been invaded by Chromolaena odorata (Asteraceae), but the consequences for arbuscular mycorrhiza fungi (AMF) remains poorly understood. This study explores changes in diverse AMF community attributes and soil available phosphorus following C. odorata invasion in forest and savanna fragments in Côte d'Ivoire (West Africa). Invaded-forest (COF) and savanna (COS) sites were compared to adjacent natural forest (FOR) and savanna (SAV) fragments, respectively. Physico-chemical variables and AMF spore density parameters were determined for soil samples from 0-20 cm depth. An 18S ribosomal RNA metabarcoding analysis of AMF communities was conducted. In addition, cowpea (Vigna unguiculata) was grown on soils collected from these sites under greenhouse conditions for determination of soil mycorrhizal infectivity. Noticeable changes in the composition of AMF communities in C. odorata relative to nearby forest and savanna non-invaded sites were observed. AMF-specific richness in COS (47 species) was lower than that in SAV (57 species) while it was higher in COF (68 species) than in FOR (63 species). COF and COS differed in AMF specific composition (Dissimilarity index = 50.6%). Chromolaena odorata invasions resulted in increased relative abundances of the genera Claroideoglomus and Glomus in COF, a decreased relative abundance of Paraglomus in COS and decreased relative abundances of Ambispora in both COF and COS. Total and healthy spore densities, cowpea root colonization intensity and soil available P were all higher in invaded sites than in natural ecosystems. Remarkably, although these values were different in FOR and SAV, they turned out to be similar in COF and COS (4.6 and 4.2 total spores g-1 soil, 2.3 and 2.0 healthy spores g-1 soil, and 52.6 and 51.6% root colonization, respectively) suggesting a C. odorata-specific effect. These findings indicate that soil mycorrhizal potential and phosphorus availability have improved following C. odorata invasion.

Touré GT ，Koné AW ，Nandjui J ，Ebou AET ，Otinga AN ，Maïga AA ，Kouadjo CGZ ，Tiho S ，Zézé A ... -  《-》

Associations of root-inhabiting fungi with herbaceous plant species of temperate forests in relation to soil chemical properties.

The overwhelming majority of research on fungal interactions with plants in the forest ecosystems of the temperate climate zone focuses on ectomycorrhizal associations and no studies so far have compared the occurrence of root-inhabiting fungi in herbaceous plant species. We thus studied arbuscular mycorrhizal fungi (AMF) and fungal root endophyte colonization rates as well as AMF species richness and composition under 19 herbaceous plant species in temperate forests (southeast Poland) in relation to soil chemical properties. Seventeen species formed arbuscular mycorrhiza (AM), while 2 were non-mycorrhizal. The intensity of AMF colonization varied between species. Relative mycorrhizal root length (MAMF%) ranged from 0% to 100%. AMF spore abundance ranged from 0 to 11.4 in 1 g of soils. Sixteen AMF species were recorded, both widespread (e.g. Funneliformis constrictum, Claroideoglomus claroideum) and rare (Acaulospora cavernata, Entrophospora infrequens). The composition of AMF species related to the plants differed. Fungal root endophytes were recorded only in some plants; dark septate endophytes (DSE) in 13 species, while Olpidium spp. in 6 species. Moreover, DSE mycelia and Olpidium spp. sporangia were observed with low abundance, and their occurrence differed between particular plant species. Among soil chemical properties, only the concentration of available phosphorus was significantly negatively correlated with the MAMF% parameter. In conclusion, several groups of root-inhabiting fungi were related to herbaceous plants; however, they occurred with varied frequency. AMF spore abundance and species richness differed as well; however, they persisted at a low level compared to other ecosystems. Nonetheless, we detected significant negative correlation between available P contents in soils and the intensity of mycorrhizal colonization, which suggests the importance of AM for the plants in sites with low P concentration.

Rożek K ，Rola K ，Błaszkowski J ，Zubek S ... -  《-》

Arbuscular mycorrhizal fungal communities in sub-Saharan savannas of Benin, West Africa, as affected by agricultural land use intensity and ecological zone.

Tchabi A ，Coyne D ，Hountondji F ，Lawouin L ，Wiemken A ，Oehl F ... -  《MYCORRHIZA》

Composition and seasonal variation of the arbuscular mycorrhizal fungi spore community in litter, root mat, and soil from a subtropical rain forest.

Community composition and seasonal variation of sporulation of arbuscular mycorrhizal fungi (AMF) have been studied in soils from many ecosystems including subtropical forest. Yet, AMF community composition has been surveyed only from the mineral soil but not from the litter layer and the root mat, and long-term variation in sporulation is not fully understood. We sampled a 75-m2 plot from a subtropical forest to determine AMF community composition in the following habitats: the litter layer, the root mat, and the mineral soil. Moreover, samples were taken in fall, winter, spring, and summer over a 2-year period to follow the seasonal variation of AMF sporulation. We detected 47 AMF species belonging to six families and 14 genera, Glomeraceae and Acaulosporaceae being the most represented families. Sixteen species were common to all three habitats, five species were shared between two habitats, and 26 species were recovered exclusively from single habitats. While species richness was not significantly different among habitats, AMF total spore numbers were significantly higher in the litter and root mat compared to the soil. PERMANOVA did not detect a significant effect of habitats on community composition when species presence/absence was considered, but significant differences between litter versus soil and root mat versus soil were detected when spore abundance was considered. A seasonal pattern of spore abundance for species was not observed over the 2-year sampling period regardless of habitat. This study revealed that (i) different AMF species sporulate in the different habitats; thus, field surveys considering only the mineral soil might underestimate species richness and (ii) AMF species sporulate asynchronously in subtropical forest.

Kemmelmeier K ，Dos Santos DA ，Grittz GS ，Stürmer SL ... -  《-》

Differential Responses of Arbuscular Mycorrhizal Fungal Communities to Long-Term Fertilization in the Wheat Rhizosphere and Root Endosphere.

Ma Y ，Zhang H ，Wang D ，Guo X ，Yang T ，Xiang X ，Walder F ，Chu H ... -  《-》