Comparison of Arbuscular Mycorrhizal Fungal Community in Roots and Rhizosphere of Invasive Cenchrus incertus and Native Plant in Inner Mongolia,China

Plant invasions could significantly alter arbuscular mycorrhizal(AM) fungal communities, but the effect may vary with plant species and local environments. Identifying changes in the AM fungal community due to plant invasion could improve our understanding of the invasion processes. Here, we examined the AM fungal community composition both in roots and rhizosphere soils of the invasive plant Cenchrus incertus and the dominant native plant Setaria viridis in a typical steppe in Inner Mongolia by using terminal restriction fragment length polymorphism analyses(T-RFLP). The results showed that AM fungal abundance in the rhizosphere soils of C. incertus was significantly lower than that of S. viridis. The AM fungal community composition in the rhizosphere soils of the two plant species also largely differed. In general, AM fungal community structures in roots corresponded very well to that in rhizosphere soils for both plant species. The dominant AM fungal type both in invasive and native plants was T-RFLP 524 bp, which represents Glomus sp.(Virtual taxa 109 and 287). Three specific T-RF types(280,190 and 141bp) were significantly more abundant in C. incertus, representing three clusters in Glomus which also named as VT(virtual taxa) 287, 64 and 214, Rhizophagus intraradices(VT 113) and Diversispora sp.(VT 60). While the specific T-RF types,189 and 279 bp, for S. viridis, only existed in Glomus cluster 1(VT 156), were significantly less abundant in C. incertus. These results indicated that AM fungi might play an important role in the invasion process of C. incertus, which still remains to be further investigated.

Rhizophagus irregularis influences As and P uptake by alfafa and the neighboring non-host pepperweed growing in an As-contaminated soil

It was documented that arbuscular mycorrhiza fungi（AMF） play an important role in protecting host plants against arsenic（As） contamination. However, most terrestrial ecosystems contain a considerable number of nonmycorrhizal plants. So far little information is available for the interaction of such non-host plants with AMF under As contaminations. By using a dual compartment cultivation system with a plastic board or a nylon mesh separating roots of non-host pepperweed from roots of the AM-host alfafa plants, avoiding direct root competition, the two plant species were grown separately or partially separated（with rhizosphere effects） in the presence or absence of the AMF Rhizophagus irregularis in As-contaminated soil. The results indicated that mycorrhiza caused phosphorus（P） concentration decrease in the non-host pepperweed, but promoted the P concentration of the AM host alfafa. Mycorrhiza is potentially helpful for non-host pepperweed to adapt to As contamination by decreasing root As concentration and showing no suppressing effect on biomass production. The study provides further evidence for the protective effects of AMF on non-host plants against As contamination, and improved our understanding of the potential role of AMF for non-host plant adaptation to As contaminated soils.