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

13.12 Arbutoid endomycorrhizas

Arbutoid mycorrhizas are also formed by plants in the order Ericales, but specifically by the plant genera Arbutus (Strawberry tree and madroña) and Arctostaphylos (Bearberry and manzanita) in the family Ericaceae and in Pyrola (Wintergreen) of the family Pyrolaceae (though some authors recognise this as a separate type of mycorrhiza). All of these are hardy, mainly evergreen shrubs which occur in the wild in harsh, high altitude regions, and are cultivated widely for their decorative foliage, flowers and berries.

The fungi of arbutoid mycorrhizas are basidiomycetes, often the same fungal species that form ectomycorrhizal associations with forest trees (see below).  Indeed, the structures of these two mycorrhizal types are very similar; arbutoid mycorrhizas have (Fig. 5):

• a well-developed fungal sheath and a Hartig net restricted to the outer layers of cells of the root and the presence of the fungal sheath, as in ectomycorrhizas, insulates the host from the soil, so everything absorbed by mycorrhizal roots must pass through this sheath (all characteristics of the ectomycorrhiza);
• but there is extensive penetration of the outer cortical cells by fungal hyphae and hyphal coils fill those cells (characteristics of the endomycorrhiza).

The arbutoid type of mycorrhiza does not fit neatly into the classification scheme that distinguished ectotrophs from endotrophs because it shares characteristics of both. The intracellular coils, along with the mantle sheath and Hartig net, and the fact that the host plant is a member of the Ericaceae are the diagnostic features of arbutoid mycorrhizas. We will see below that there is another intermediate type of mycorrhiza, called the ectendomycorrhiza, which is an ectomycorrhiza in which the hyphae penetrate the outer cortical cells, and fill them with coils, which the hyphae of  ectomycorrhizas do not normally do. In this case, and this distinguishes arbutoid from ectendomycorrhiza, the plant host is a member of the Coniferophyta (cone-bearing gymnosperm trees, including pines, yews, but also the ‘living fossil’ Ginkgo).

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