Comparison of two main mycorrhizal types

Transcription

1 Comparison of two main mycorrhizal types VAM (Endos) Ectos Plant hosts Most vascular plants, including herbs, shrubs, trees. examples of tree you know: Maples, Ash, giant Sequoia, Sequoia, Incense Cedar association is not obligate in most hosts Most temperate forest trees, some shrubs. examples you know: Pines, Douglas-fir, true firs, Oaks, Manzanita, Madrone association is obligate for the hosts Fungi involved ca. 150 known species Zygomycetes (Glomales) all obligate associates, little "apparent" specificity ca known species Basidiomycetes, Ascomycetes, (Zygomycetes) most obligately associated, some highly host specialized, most not. Cost to hosts moderate (<15% of C) high (20-80% of C) Longevity of 2-3 weeks Several months to a year individual associations Environment Richer soils, lacking large accumulations of organic detritus Poor soils with large accumulations of organic detritus Primary nutrients P, trace elements, (N?) N, P, trace elements gathered Morphology no obvious external signs of colonization, cortex cell are penetrated and arbuscules (highly branched haustoria) and sometimes vesicles are formed roots are swollen, often branched, covered by a "mantel" of hyphae, intercellular hyphae (hartig net) but usually no penetration of cells

2 Root of Phaseolus vulgaris colonized by arbuscular mycorrhizal fungi vesicle arbuscules 10µm (c) D. Redecker

3 Arbuscule and vesicle 10µm (c) D. Redecker, K. Wex

4 Arbuscular mycorrhiza (Plantago media and Glomus clarum) extraradical hyphae spore 100µm (c) D. Redecker

5 Photo from Ann Pringle

6 Geosiphon pyriforme photo from Arthur Schlüßler

7 Comparison of two main mycorrhizal types VAM (Endos) Ectos Plant hosts Most vascular plants, including herbs, shrubs, trees. examples of tree you know: Maples, Ash, giant Sequoia, Sequoia, Incense Cedar association is not obligate in most hosts Most temperate forest trees, some shrubs. examples you know: Pines, Douglas-fir, true firs, Oaks, Manzanita, Madrone association is obligate for the hosts Fungi involved ca. 150 known species Zygomycetes (Glomales) all obligate associates, little "apparent" specificity ca known species Basidiomycetes, Ascomycetes, (Zygomycetes) most obligately associated, some highly host specialized, most not. Cost to hosts moderate (<15% of C) high (20-80% of C) Longevity of 2-3 weeks Several months to a year individual associations Primary nutrients P, trace elements, (N?) N, P, trace elements gathered Morphology no obvious external signs of colonization, cortex cell are penetrated and arbuscules (highly branched haustoria) and sometimes vesicles are formed roots are swollen, often branched, covered by a "mantel" of hyphae, intercellular hyphae (hartig net) but usually no penetration of cells

8 Ectomycorrhizal root in section From Smith and Read 1997

9 The Ectomycorrhiza Traditional view 1. Structure Clowes 1951 France & Reid 1983

10 Ectomycorrhizal fungi are diverse at multiple spatial scales

11 The mycelium provides the absorptive system of the plant

12 Ericoid Mycorrhizae Mol. Ecol. 5(1)

13 Orchid mycorrhizae (Peletons)

14 Early stage Fungi ( r ) Fruit under very young trees Fruit at periphery of older trees Establish on seedlings in disturbed soil Spores are effective inoculum Late stage Fungi ( K ) Fruit under older trees Fruit near stem of older trees Establish on seedlings in undisturbed soil Spores are not effective inoculum

15 Attributes of Early versus Late-stage Ectomycorrhizal Fungi as defined by Deacon and Fleming (1992) Early stage (ruderal) Late stage (K-selected) fruit bodies develop in early years beneath young trees fruit bodies develop in later years as trees mature fruit bodies and mycorrhizas seen near periphery of expanding root system infect readily from spores or mycelial inocula added to unsterile soil persist when aseptically inoculated seedlings are transplanted to soil have low sugar demand for extension growth and infection in culture spores germinable in culture or in presence of plant roots some are known to infect as monokaryons Example genera: Lacarria, Hebeloma, Inocybe fruit bodies and mycorrhizas seen mainly in older root zones do not infect from spores or mycelia added to unsterile soil persist poorly after transplanting have high sugar demand for extension growth and infection in culture spores not readily germinable in culture have not been shown to infect as monokaryons Russula, Amanita, Boletus,

16 In Nature prefire trees Russula spp. Tomentella spp. Amanita many s but few ascomycetes Post-fire seedlings forest Rhizopogon spp. Ascomycetes: Wilcoxina spp Tuber spp. Tomentella Russula spp. Amanita spp. and s Post-fire seedlings scrub Rhizopogon Soil Bioassay (lab) Rhizopogon spp. Tomentella Ascomycetes Rhizopogon spp. Tomentella Ascomycetes Rhizopogon

17 Ectomycorrhizal community structure based on root tip colonization Data from mature Pt. Reyes, Bishop pine communities summarized by families.

18 Rhizopogon species are dominants in seedling bioassay

19 Rhizopogon and Ascomycetes dominated the roots of pine seedlings after the Pt. Reyes fire * * * R. salebrosus * Rhizopogon * * R. occidentalis R. olivaceotinctus R. salebrosus * R. salebrosus R. occidentalis * R. occidentalis R. olivaceotinctus *

20 Pterospora Epiparasitism

21 Monotropes (Ericaceae) epiparasitism Basidiomycetes

22 Facultative epiparasitism? Douglas-fir seedling and manzanita

23 Parasitism of surrounding plants by Tuber melanosporum an ectomycorrhizal fungus on oak

24 Species diversity of AM fungi effect diversity of plant community and ecosystem function From Van der Heijden et al. 1998

25 From Francis and Read 1995

26 From Vázquez et al FEMS microbiol Ecol. 13:93-104

27 Anthrocobia sp Phoenicoid funi Rhizina undulata