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

Table of Contents

1. Chapter 13: Ecosystem mycology: saprotrophs, and mutualisms between plants and fungi
2. Chapter 14: Fungi as pathogens of plants
   1. Fungal diseases and loss of world agricultural production
   2. A few examples of headline crop diseases
   3. The Rice Blast fungus Magnaporthe oryzae (Ascomycota)
   4. Armillaria (Basidiomycota)
   5. Pathogens that produce haustoria (Ascomycota and Basidiomycota)
   6. Cercospora (Ascomycota)
   7. Ophiostoma (Ceratocystis) novo-ulmi (Dutch Elm disease or DED) (Ascomycota)
   8. Black stem rust (Puccinia graminis f. sp. tritici) threatens global wheat harvest
   9. Plant disease basics: the disease triangle
   10. Necrotrophic and biotrophic pathogens of plants
   11. The effects of pathogens on their hosts
   12. How pathogens attack plants
   13. Host penetration through stomatal openings
   14. Direct penetration of the host cell wall
   15. Enzymatic penetration of the host
   16. Pre-formed and induced defence mechanisms in plants
   17. Genetic variation in pathogens and their hosts: co-evolution of disease systems
   18. Chapter 14 References and further reading
   19. Buy a PDF of Chapter 14
3. Chapter 15: Fungi as symbionts and predators of animals

14.5 Pathogens that produce haustoria (Ascomycota and Basidiomycota)

Flax rust (Melampsora lini, Basidiomycota) and barley powdery mildew (Blumeria graminis (also known as Erysiphe graminis), Ascomycota), share the ability to produce specialised feeding structures called haustoria which penetrate the living cells of their host plant. This gives them intimate contact with live host cell membranes through which they can extract nutrients and suppress plant defences. Smut fungi (species of Ustilago, Basidiomycota) are particularly important pathogens of cereal crops. They do not form haustoria but nevertheless make close contact with living host cells through intracellular hyphae which invaginate the host cell membrane.

All these pathogens are of major importance to agriculture and comparison of the ways in which they interact with their hosts in terms of cross-recognition and cross-signalling, and the virulence and resistance genes involved in these interactions is seen as a way of improving understanding of the biology of their relationships with their host plants and a way to improve food production (Ellis et al., 2007). Haustoria are the key features of these extremely successful plant pathogens, the obligate biotrophs.

The broad phylogenetic range of organisms that produce haustoria suggests that these structures are specific adaptations to close exploitation of their respective host plants that have arisen many times during evolution. Since it became possible to analyse haustorial function at a molecular level a picture began to emerge indicating that haustoria not only function in nutrient uptake but also synthesise and secrete a panel of virulence factors. Proteins called effector proteins, which manipulate the physiological and immune responses of host cells, redirecting the host’s metabolic flows to the benefit of the pathogen (Voegele & Mendgen, 2003; Garnica et al., 2014).

All of these pathogens are of major importance to agriculture and comparison of the ways in which they interact with their hosts in terms of cross-recognition and cross-signalling, and the virulence and resistance genes involved in these interactions is seen as a way of improving understanding of the biology of their relationships with their host plants and a way to improve food production (Ellis, Dodds & Lawrence, 2007).

Resources Box 14.1 Where to find more information about crop diseases, crop losses, plant pathogens and food and agriculture statistics We have a page giving references to scientific papers and hyperlinks to online resources. CLICK HERE to open the page in a new window

 

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Updated July, 2019