1.1 What and where are fungi?

‘How many of you think that fungi are bacteria?’ is a question asked at a recent Summer School for year 10 pupils (4th year in secondary school, 14 years of age at entry), by one of the pupils who had attended a workshop session of ours. When all attendees (approximately 170 pupils) were asked “Hands up all those who think fungi are plants”, about 15 hands went up, but when asked “Hands up all those who think fungi are bacteria”, at least 150 hands went up!

As teachers we are used to battling against the mistaken idea that fungi are plants, but it was a shock to find that so many pupils believe that fungi are bacteria so close to the end of their statutory education. After all, it’s a bigger error than for them to think that whales are fish; at least whales and fish are in the same biological Kingdom. Does such ignorance matter? We say it does. The practical reason it matters is because the activities of fungi are crucially important in our every day lives. The educational reason it matters is that fungi form what is arguably the largest kingdom of higher organisms on the planet. Ignorance of this kingdom is a major blot on our personal education.

Fungi are not bacteria, because fungi are eukaryotes and they have the complex cell structures and abilities to make tissues and organs that we expect of higher organisms. Unfortunately, even though fungi make up such a large group of higher organisms, most current biology teaching, from school-level upwards, concentrates on animals, with a trickle of information about plants. The result is that the majority of school and college students (and, since they’ve been through the same system, current University academics) are ignorant of fungal biology and therefore of their own dependence on fungi in everyday life. This institutional ignorance about fungi, generated by the lack of an appropriate treatment of fungal biology in national school curricula, seems to apply throughout Europe, North and South America, and Australasia; indeed, most of the world.

The feature which has figured most in our decision to write this textbook is that although fungi comprise what is arguably the most pivotal Kingdom of organisms on the planet, these organisms are often bypassed and ignored by the majority of biologists. We say ‘pivotal’ because molecular phylogenies place animals and fungi together at the root of evolutionary trees. It is likely that the first eukaryotes would have been recognised as ‘fungal in nature’ by features presently associated with that Kingdom. So in a sense, those primitive ‘fungi’ effectively invented the eukaryotic lifestyle.

The contribution that fungi make to human existence is close to crucial, too. Imagine life without bread, without alcohol, without soft drinks, without cheese, coffee or chocolate; without cholesterol-controlling drugs (the ‘statins’) or without antibiotics, and you are imagining a much less satisfactory existence than we currently enjoy. As we will show in later chapters:

  • Fungi (known as anaerobic chytrids) help to digest the grass eaten by cows (and other domesticated grazing animals) and by so doing indirectly provide the milk for our breakfast, the steak for dinner and the leather for shoes.
  • Fungi make plant roots work more effectively (more than 95% of all terrestrial plants depend on mycorrhizal fungi) and, even leaving aside the effect of this on the evolution of land plants, by so doing mycorrhizal fungi help provide the corn for our cornflakes, oats for our porridge, potatoes, lettuce, cabbage, peas, celery, herbs, spices, cotton, flax, timber, etc. And even oxygen for our daily breath.
  • The characteristic fungal life style is the secretion of enzymes into their environment to digest nutrients externally; and we harness this feature in our biotechnology to produce enzymes to start our cheese-making, clarify our fruit juices, distress denim for ‘stone washed’ jeans, and, conversely, provide fabric conditioners to repair day-to-day damage to our clothes in the weekly wash.
  • Fungi also produce a range of compounds that enable them to compete with other organisms in their ecosystem; when we harness these for our own purposes we create products like:
    • cyclosporine, which suppresses the immune response in transplant patients and prevents organ rejection,
    • the statins, which help increase the lifespan of so many people these days by controlling cholesterol levels,
    • and even today’s most widely used agricultural fungicides, the strobilurins.

But fungi are not always benevolent. There are fungal diseases of all of our crops that we need to understand and control. In many cases crop losses of 20 to 50% are expected by the agricultural industry today. As the human population increases such losses in primary production cannot be sustained. And there is more to fungal infection of man than Athlete’s foot and a disfigured toenail. Opportunistic fungal infections of patients are an increasing clinical challenge as the majority of patients with chronic immunodeficiency now die of fungal infections; and yet we lack a sufficient range of good drugs to treat fungal infections.

Our answers to the questions in the title of this section ‘What and where are fungi?’ are that fungi comprise the most crucial Kingdom of eukaryotic organisms on the planet, and that they exist everywhere on planet Earth.

Updated December 16, 2016