Effects of Different Arbuscular Mycorrhizal Fungi on Physiology of Viola prionantha under Salt Stress

Arbuscular mycorrhizal(AM)fungi distribute widely in natural habits and play a variety of ecological functions.In order to test the physiological response to salt stress mediated by different AM fungi,Viola prionantha was selected as the host,the dominant AM fungus in the rhizosphere of V.philippica growing in Songnen saline-alkali grassland,Rhizophagus irregularis,and their mixtures were used as inoculants,and NaCl stress was applied after the roots were colonized.The results showed that V.philippica could be colonized by AM fungi in the field and the colonization rate ranged from 73.33%to 96.67%,and Claroideoglomus etunicatum was identified as the dominant AM fungi species in the rhizosphere of V.philippica by morphology combined with sequencing for AM fungal AML1/AML2 target.Inoculation with both the species resulted in the formation of mycorrhizal symbiosis(the colonization rate was more than 70%)and AM fungi significantly enhanced plants’tolerance to salt stress of varying magnitude.Higher activity of antioxidant enzymes and augmented levels of proline and other osmoregulators were observed in AM plants.The content of MDA in CK was higher than that in the inoculations with the stress of 100,200,and 250 mM.All indices except soluble protein content and MDA content were significantly correlated with AM fungal colonization indices.The analysis for different AM fungal effects showed that the mixtures and R.irregularis worked even better than C.etunicatum.These results will provide theoretical support for the exploration and screening of salt-tolerant AM fungi species and also for the application of AM-ornamental plants in saline-alkali urban greening.

A conserved arbuscular mycorrhizal fungal core-species community colonizes potato roots in the Andes

Plant-symbiotic arbuscular mycorrhizal fungi(AMF)are of high global ecological and economic importance,but describing environmental communities of AMF at the species level remains a challenge,despite the need to understand AMF-plant preferences and to apply AMF in sustainable agriculture.Here,the potato-associated AMF species community composition was assessed for three Andean countries along an altitudinal gradient and at different plant stages,by using 454 GS-FLX+sequencing of a 760 bp LSU rRNA gene PCR amplicon.Two methods were compared:defining OTUs based on a simple sequence similarity threshold,or affiliating reference sequences to species based on a high throughput phylogenetic annotation approach using an evolutionary placement algorithm(EPA).The EPA-based approach was not only more precise,but also fundamental to robustly unveil the AMF species community composition.The principal advantage of this approach was also demonstrated by using artificially constructed datasets based on validated public database sequences.The affiliation of sequence reads to species using phylogenetic annotation revealed a surprisingly conserved AMF core-species community structure in Andean potatoes,regardless of different plant stages and environmental factors.In total,41 species were detected and in some cases more than 25 species were found colonizing an individual root system.Acaulospora species were identified as dominant colonizers,co-occurring with Cetraspora nodosa and certain Claroideoglomus and Rhizophagus species in most potato root samples.