[Relationship of AM fungi with non-mycorrhizal plants.] / AMçœŸèŒä¸ŽéžèŒæ ¹æ¤ç‰©çš„ç›¸äº’ä½œç”¨å ³ç³».

As a kind of globally widely distributed soil microorganism, arbuscular mycorrhizal (AM) fungi form the symbiosis with the majority of land plants, which is important for plant nutrition and ecosystem functioning. Few vascular species are considered to be nonmycorrhizal, especially those within the families Amaranthaceae, Chenopodiaceae, Carophyllaceae and Brassicaceae. At present, the interactions between these non-host plants and AM fungi are few and scattered, lacking systematic summary. In this paper, the type of non-host plants, the reason of low mycotrophy, and the effect of AM network formed by neighbor plants on AM fungi colonization on the non-host, and the possible interaction between AM fungi and non-host, as well as the material exchange between plants and AM fungi and their possible ecological functions were reviewed in order to give some new ideas on the function of the nonmycorrhizal plants in the fragile ecosystems.

[Ecological distribution of arbuscular mycorrhizal fungi in alpine grasslands of Tibet Plateau].

Seventy soil samples with the roots of 37 dominant or common plant species on the grasslands in south and north Tibet Plateau were collected to study the ecological distribution of arbuscular mycorrhizal (AM) fungi in the investigation area. A total of 35 AM fungi species belonging to 5 genera were isolated, among which, 18 species belonged to Glomus, 9 species belonged to Acaulospora, 6 species belonged to Scutellospora, 1 species belonged to Entrophospora, and 1 species belonged to Paraglomus. There were 23 AM fungi species belonging to 4 genera isolated from south Tibet, and 22 species belonging to 4 genera from north Tibet. The Shannon diversity index of AM fungi in south and north Tibet Plateau was 2.31 and 2.75, respectively, and the spore density and species richness were significantly higher in north Tibet than in south Tibet. In different ecological zones, lesser AM fungi common species were found, species distribution was more site-specific, and different dominant species were observed. In alpine grassland, mountain meadow, and alpine meadow, the Shannon index of AM fungi was 1.91, 1.83, and 1.80, respectively; while in severely degraded temperate grassland, this index was only 1.64. The highest species richness of AM fungi occurred at the altitude of 4000-4600 m, but the highest Shannon index and species evenness occurred at the altitude of 4600-5220 m, with the values being 2.42 and 0.79, respectively. At all altitudes, Glomus was the dominant genus, and its relative abundance was higher when the altitude was below 4000 m. Acaulospora was mainly observed at the altitudes higher than 4000 m, Scutellospora was mainly distributed at the altitude 3500-5220 m, Paraglomus mainly occurred in the north alpine meadow with an altitude of 4000-5220 m and occasionally in the alpine steppe, whereas Entrophospora was only found in the south temperate grassland with an altitude of 3500-3700 m.

[Field inoculation effect of AM fungi on Tibet plateau Stipa bungeana grassland].

A field experiment was conducted on the Tibet plateau Stipa bungeana grassland to investigate the effects of arbuscular mycorrhizal fungi (AMF) inoculation on S. bungeana growth and its phosphorus uptake, and on soil microbial communities under unsterilized condition. The results showed that AMF inoculation increased the AMF spore density, infection rate and infection intensity in rhizosphere soil significantly, but had less effect on arbuscule richness. The infection rate of AMF increased with its increasing spore density, and the plant dry weight and P uptake of S. bungeana increased significantly with AMF infection rate. Similar results were observed in S. bungeana root dry weight and its P content. AMF inoculation increased the acid and alkaline phosphatase activities and bacterial biomass in rhizosphere soil, but had less effect on fungal and actinomyces communities. The infection effect of AMF varied with inoculation treatments, being in the sequence of Glomus mosseae + G. intraradices + Scutellospora calospora > G. mosseae + G. aggregatum > Glomus sp. > G. mosseae > G. mosseae + G. etunicatum + G. intraradices + S. erythropa > G. geosporum.