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Host Effects On Arbuscular Mycorrhizal Fungi—functioning,Distribution And Diversity

Posted on:2014-03-29Degree:DoctorType:Dissertation
Country:ChinaCandidate:H S YangFull Text:PDF
GTID:1260330401469937Subject:Ecology
Abstract/Summary:PDF Full Text Request
The symbiotic interaction between arbuscular mycorrhizal (AM) fungi and host plants is a facinatic topic in ecological studies. Studies have been examined on how AM fungi regulate aboveground plant community, however, how plants affect AM fungi is not well documented. My study, here, address the following questions:(1) Effects of host plants and water stress on AM fungal functioning;(2) Effects of host selection on geographical distribution of AM fungi; and (3) Effects of host selection on the evolution and generation of AM fungal diversity patterns. Metadata mining, meta-analysis, greenhouse experiment and field sampling were used in this study. The results are as follows.1. AM fungal symbiotic functioning. Meta-analysis showed that single and multiple AM fungal inoculation did not significantly differed in promoting plant growth, suggesting that function may not be complementary at AM fungal species level, and "super fungus" effect may be dominated. Host plants differed in responding to AMF. Growth response of C4and tap root plants to AMF was stronger than C3and fibrous root plants, respectively. Root compartment experiment suggested that AM fungi intensified intraspecific competition of Medicago sativa with increasing water availability; this is contrasting with the effects of other rhizosphere factors (including soil solution and root systems).2. AM fungal geographic distribution.18S rDNA evidence indicated that AM fungi had high endemism at global scale, and the distribution was affected by host plants, dispersal ability, biogeography and temperature, etc. AM fungal global distribution was not random and exhibited an "everything is not everywhere" pattern. ITS rDNA evidence further suggested that host plant was the main and direct driving factor for AM fungal global distribution, while the effects of biogeographical factors, spatial isolation and climate on AMF distribution were through affecting host plant’s distribution. Our field study also indicated that aridity decreased vegetation productivity and further decreased AM fungal abundance.3. Evolution and generation of AM fungal diversity. AM fungal diversity and host-specificity differed among plant phylogenetic groups:early-originated plant lineages with lower AM fungal diversity and host-specificity, while the later-originated plant groups with higher diversity and host-specificity. In natural AM fungal communities, Glomus group A had much higher species richness, which was possibly caused by host preferential selection. In different plant phylogenetic lineages, Glomus group A accounted for above60%for all AM fungal species. Meta-analysis showed that Glomus group A had stronger symbiotic functioning, promoted plants acquiring more P and N nutrients and thus made plants have a better growth. Meanwhile, Glomus group A could enhance host plants with higher tolerance and resistance towards abiotic and biotic stresses, such as inhibiting the growth and reproduction of nematodes and fungal pathogens.
Keywords/Search Tags:Arbuscular mycorrhizal fungi, biogeography, data mining, host selection, meta-analysis, functional complementarity, rhizosphere interaction, neighbor effect
PDF Full Text Request
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