How we discovered a hidden world of fungi inside the world ...

How we discovered a hidden world of fungi inside the world's biggest seed bank

March 22 2021, by Rowena Hill

Credit: Rowena Hill, Author provided

This was the moment of truth. We'd spent countless hours meticulously sterilizing seeds (1,710, to be specific), filling the lab with a cacophony of rattling as we shook them in bleach. We'd built a fungus city: great tower-blocks of petri dishes stacked on the lab workbenches, with different colors, textures and shapes of fungi all emerging inside. We'd extracted enough DNA that the freezer, stuffed full of tubes, threatened to revolt.

1/15

Finally the time had come for me to analyze all the data, and discover just what we'd managed to find after all these months of work. In the first study of its kind, to our knowledge, in a major seed bank, we found hundreds of fungi hidden inside seeds from the Millennium Seed Bank, some of which are likely to be species new to science and could be crucial for the future of plant health.

I can't remember the moment when I first decided to study fungi. If only I had an anecdote about my time as a biology undergraduate looking down the microscope at some spores for the first time, overcome by their sheer majesty--but that would be fiction. For one thing, fungi barely appeared in my degree, and when they did it was usually in the negative context of causing disease.

Given that fungi are a whole kingdom of species which, alongside animals and plants, belong to the major domain of planet Earth's multicellular life together called the "eukaryotes", this is perhaps surprising. Yet this is the typical experience in both school and higher education (in the UK and the US at least) and, unsurprisingly, when you don't teach students about fungi, they don't go on to study fungi. Which leads to fewer researchers studying fungi that can teach students about fungi and ... you get the picture. Long story short, fungi are incredibly understudied compared to their sister kingdoms of animals and plants.

I really can't emphasize enough how much of an oversight this is. The latest estimate of the total number of fungal species is 6.2 million. To put that in context, that would mean our planet is inhabited by 15 times more fungi than plants. Other recent estimates for fungal diversity have ranged widely from 2.2 million to 165 million species--but no matter which you go with, the numbers are all far greater than the 150,000 fungi which scientists have already found and described.

We've barely scratched the surface, and I mean that quite

2/15

literally--countless fungi will be underground and inside other organisms. These microscopic fungi, or more simply "microfungi," are invisible to the naked eye, and so for a long time have remained under the radar. But that doesn't mean they're unimportant. Quite the opposite. Yes, some will be pathogens, which can cause disease in plants and animals. These tend to be the fungi that get the most attention, both in terms of public awareness and scientific research, and not without some good reason. With our increased global travel and trade, not to mention our contributions to climate change, we're creating a perfect opportunity for new fungal pathogens to emerge and thrive.

The proportion of scientific papers published each year for animals, plants and fungi. Data from EuropePMC.

But there's so much more than just the pathogens. There are also the

3/15

recyclers ("saprotrophs"), which break down organic matter and return nutrients to the soil in the continuous cycle of life and death. We live on a planet of finite resources, so it's thanks to these little fungi doing the work to recycle them that our natural world can exist at all.

Countless fungi play key roles in modern society: they can be a source of medicines such as antibiotics and immunosuppressants, industrial enzymes for detergents and manufacturing and new biomaterials to replace plastics. Even the humble baker's yeast, which underpins our everyday food and drink, can be used in the lab to study human genetics or modified to produce important compounds. And these are just the fungi we already know about--imagine the useful properties awaiting discovery in the fungi we are yet to find.

And maybe most famously there are the symbiotic partners known as mycorrhizal fungi, which form a relationship with plant roots, usually for mutual benefit: they can help the plant take up water and nutrients in return for carbohydrates. These fungi can form vast underground networks of nutrient exchange between plants, popularly known as the "wood wide web". As if that wasn't enough, mycorrhizal fungi also help to increase the amount of carbon stored in the soil, and so play an important role in regulating global climate.

Life as we know it would, quite simply, be lost without fungi.

Enter the endophytes

Which brings me to the fungi I study. Mycorrhizal fungi aren't the only ones to be found when we look at plants. All plant tissues contain fungi, in much the same way that us animals have an array of microorganisms living inside us: our "microbiome." These microfungi of plants are called fungal endophytes (endo=in, phyte=plant), and are defined by the fact that they live inside plants without causing any visible symptoms of

4/15

disease. The sequencing revolution, which has enabled us to detect otherwise imperceptible organisms from mere traces of their DNA, has transformed our awareness of these microscopic fungi. A single plant individual is capable of hosting countless different fungal species.

5/15

 ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download