21st Century Guidebook to Fungi, SECOND EDITION, by David Moore, Geoffrey D. Robson and Anthony P. J. Trinci

Table of Contents

1. Chapter 12: Development and morphogenesis
2. Chapter 13: Ecosystem mycology: saprotrophs, and mutualisms between plants and fungi
   1. Ecosystem mycology
   2. Fungi as recyclers and saprotrophs
   3. Make the earth move
   4. Fungal toxins: food contamination and deterioration
   5. Decay of structural timber in dwellings
   6. Using fungi to remediate toxic and recalcitrant wastes
   7. Release of chlorohydrocarbons to the atmosphere by wood decay fungi
   8. Introduction to mycorrhizas
   9. Types of mycorrhiza
   10. Arbuscular (AM) endomycorrhizas
   11. Ericoid endomycorrhizas
   12. Arbutoid endomycorrhizas
   13. Monotropoid endomycorrhizas
   14. Orchidaceous endomycorrhizas
   15. Ectomycorrhizas
   16. Ectendomycorrhizas
   17. The effects of mycorrhizas and their commercial applications, and the impact of environmental and climate changes
   18. Introduction to lichens
   19. Introduction to endophytes
   20. Epiphytes
   21. Chapter 13 References and further reading
   22. Buy a PDF of Chapter 13
3. Chapter 14: Fungi as pathogens of plants

13.16 Ectendomycorrhizas

Rather than being a definitive subgroup, ectendomycorrhiza is a descriptive name for mycorrhizal roots that exhibit characteristics of both ectomycorrhizas and endomycorrhizas. Ectendomycorrhizas are essentially restricted to the plant genera Pinus (pine), Picea (spruce) and, to a lesser extent, Larix (Larch). Ectendomycorrhizas have the same characteristics as endomycorrhizas but also show extensive intracellular penetration of the fungal hyphae into living cells of the host root. Formation of ectendomycorrhizas begins with formation of a Hartig net, which grows behind the apical meristem of the growing root.

The Hartig net hyphae grow between the epidermal and outer cortical cells and later extend to the inner cortex. Growing up the older parts of the root, intracellular penetration increases, once inside a cell, the hyphae branch repeatedly. The oldest plant cells become almost filled with coils of septate hyphae. The ectendomycorrhizal association can persist for a full year, and there is no evidence of hyphal degeneration or lysis. Ectoendomycorrhizal formation induces the growth of short roots, similar to the ectomycorrhizal association. Emergent roots become covered in a matrix of highly branched hyphae; the coarse sheath develops between root hairs and eventually covers the entire root.

Assessment of the influence of inorganic and organic phosphorus and the lack of phosphorus in the culture medium on the type of mycorrhizal colonisation formed (ecto-, ectendo-, or endomycorrhiza) during Helianthemum almeriense × Terfezia claveryi symbiosis in vitro revealed that the mycorrhizal types formed depended on the phosphorus source in the medium, suggesting that it is the organic phosphorus that induces the formation of intracellular colonisation (Navarro-Ródenas et al., 2012).

The fungi involved in ectendomycorrhizal symbioses are Ascomycota; most belong to the genus Wilcoxina and the majority of isolates can be assigned to two species, Wilcoxina mikolae and W. rehmii. These two taxa occupy distinctive habitats: W. mikolae is a chlamydospore-producing fungus, found predominantly in disturbed mineral soils, whilst W. rehmii thrives in peaty soils, but does not produce chlamydospores.

For the price of a Coffee & Iced Lemon Loaf Cake ($5) you can buy yourself a PDF file of this chapter from 21st Century Guidebook to Fungi Online. Our PDFs feature an elegantly simple text layout that is easily readable on your mobile or other device, and all hyperlinks are live so you can continue to enjoy the Internet experience. Chapter 13: Ecosystem mycology: saprotrophs, and mutualisms between plants and fungi. With the appendix item attached to this chapter: Ecosystem Services in the 21st Century Guidebook to Fungi making a 69-page PDF file priced at FIVE US$ ($5) Delivered to you by SendOwl Not convinced yet? Download a FREE sample HERE

 

Updated July, 2019