Ecto and endomycorrhizae and their significance

A part of Botany (Hons) syllabus in Mycopathology illustrates the basic differnces in ectomycorrhizae and endomycorrhizae as well as their significance

1. Ectomycorrhizae , endomycorrhizae and their significance Botany ( Hons ) Sem II CC-3; Unit 8 (Ref : G. Hait , A textbook of Mycology, NCBA;) Dr. Rita Som Paul Associate Professor Botany Department Siliguri College Siliguri

2. What is mycorrhiza ? ‘ Mykes ’- mushroom (Gr.) ‘ rhiza ’ – root Symbiotic association between plant root and fungi with biderectional exchange of of nutrients between the partners Named so by A.B. Frank (1885) About 90% of all land plants are associated with this phenomenon

3. Types of Mycorrhizae (Peterson & Farquhar, 1994): 1. Ecto mycorrhizae 2. Vescicular-Arbuscular mycorrhizae (VAM) 3. Ectendo mycorrhizae ( arbutoid ) 4. Ericoid mycorrhizae 5.Gentianoid mycorrhizae 6. Orchidoid mycorrhizae 7. Monotropoid mycorrhizae Bradly speaking, there are three types- ecto , ectendo and endo . Endomycorrhiza includes  arbuscular ,  ericoid , and  orchid mycorrhiza , while  arbutoid mycorrhizas  can be classified as  ectoendomycorrhizas .  Monotropoid   mycorrhizas form a special category.

4. Ectomycorrhizae (ECM) ‘ sheathing mycorrhiza ’ Occur in 3% of all seed plants Fungus enters cortex forming “ Hartig Net” but never inside the endodermis or stele Intercellular hyphae ( extracellular) In northern temperate regions, plants such as pine ( Pinus ), spruce ( Picea ), fir ( Abies ), poplar ( Populus ), willow ( Salix ), beech ( Fagus ), birch ( Betula ) and oak ( Quercus ) typify the ECM association.  In the southernhemisphere   Eucalyptus  and  Northofagus  (Southern Beech) are important genera as is the Dipterocarpaceae Fungi- Basidiomycota ( Amanita muscaria , most Agarics).  Ascomycota ( Boletus spp , Tuber magnatum etc); Zygomycete genus  Endogone ,

5. Some macroscopic images of ecto Tuber magnatum ( Ascomycota ) Amanita muscaria ( Basidiomycota )

6. Some macroscopic images of ecto - Ref : Moore et al, 2011; mycorrhizas.info Small parts of root systems. A-D- Douglas fir ( Pseudotsuga metziesii ) ; A-with truffle Hysterangium ; B-with basidiomecete Rhizopogon vinicolor ;C -with polypore Bissoporrya terrestris ; D-with Lactarius sanguiflurus ;E - A.muscaria with Picea sitchensis ; F- A.muscaria with Pinus radiata ; E- Pinus sp seedling with Siullus bovinus in experimental microcosm

7. Some microscopic images of ecto - A. TS of ectomycorrhizal   Tsuga canadensis  (hemlock) with labyrinthine Hartig net hyphae (arrows) penetrating between the cortical cells of the root and completely surrounding many cells; note tannin-filled epidermal cells in the inner mantle (asterisk); scale bar = 100 µm) B. root cross-section of ectomycorrhizal   Populus tremuloides  (quaking or trembling aspen) showing labyrinthine Hartig net hyphae (arrows) around elongated epidermal cells.

8. Some microscopic images of ecto - Hartig net in Pinus sp .

9. Importance of ectomycorrhiza Enhances nutrient and water absorption by increase in surface are Nutrient mobilization through biological whithering Enhances uptake of N,P,K, Ca, NA,Fe,Zn , S and Mo and translocation Enhances degradation of complex minerals and organic substances Provide protection against pathogens by physical barrier, by favouring growth of beneficial rhizosphere microorganisma and use of surplus carbohydrate Provides host plant with hormones ( auxin , cytokinin , gibberellin ) and vit B

10. Ectomycorrhiza vs endomycorrhiza

11. Ectomycorrhiza (ECM) vs endomycorrhiza (VAM/AM) Ecto /ECM Endo- VAM/AM Hyphae are only intercellular both – inter and intra cellular thick fungal mat (mantle) around the roots Mantle absent Formation of Hartig net No Hartig net Vesicles and arbuscules are absent Vesicles (one celled) and /or arbuscules (dichotomous) are present Separate type of mycorrhiza Includes AM/VAM ,  ericoid , and  orchidoid mycorrhiza , Fungal partner is Basidio / Ascomycota Eg Amanita muscarina ; Tuber melanospora Fungal partner belongs to Zygomycota , occasionally Basidiomycota Eg . Glomus sp, Gyrospora sp Rhizoctonia sp, Corticium sp Cause extensive branching and growth of roods No such effect

12. Maicroscopic images of endomycorrhizae Arbuscular Glomus on Allium

13. Importance of endomycorrhiza Mycorrhizal association is obligatory for germinating orchid seeds. Egs Rhizoctonia repens and Orchis militaris Inoculation of VAM as biofertilizer provides possibility of uptake of P in P- deficient soils Trees with endomycorrhizae act as first invaders in wastelands and pioneers in barren land. Root colonizatin provides protection from parasitic fungi and nematodes Crops like onion, strawberry, corn etc depend on mycorrhiza in absence of P Can be cultured on maize and sudan grass for mass inoculum multiplication Help in uptake of mineral ionsand act as reservoir.

14. End Note: Mycorrhizae play a very important role in agriculture and forestry. In spite of the differences in structure, both the types help in uptake of nutrients and protect from plant pathogens Ectomycorrhizae have mostly macroscopic fruit bodies and more associated with forest ecosystem Till now, most of the endomycorrhizae studied are only microscopically visible and associated with cultural crops like tea and maize