Mushrooms have relationships, too.
But we’re not talking about the romantic kind. We’re talking about the symbiotic relationship between fungi and plants. And this isn’t any old relationship… It’s incredibly important to life on earth. So, what is mycorrhiza? And why is it so darn important?
What Is Mycorrhiza?
Mycorrhiza is derived from the classic Greek words for “mushroom” and “root.” It refers to the symbiotic relationship between plant roots and fungi. The interaction is mutually beneficial – the plant makes organic molecules for the fungus to use, and in turn, the fungus provides the plant with water and nutrients. It’s a bit of a “you scratch my back and I’ll scratch yours” type of deal.
But to completely understand mycorrhiza, we must first understand the role of mycelium in the food web. If we were to liken mushrooms to a flower, mycelium would be the underground root system and the mushroom would be the flower. And it’s the mycelium root system that roams through the underground world – connecting with plant roots, breaking down molecules and playing a major role in the carbon cycle.
So, what exactly do plants and mushrooms share with each other?
How Does Mycorrhiza Work?
Let’s think back to your high school science days where you learnt about photosynthesis – the process where plants turn the sun's energy into carbohydrates. Well, turns out, plants don’t keep these carbohydrates (like glucose and sucrose) all to themselves… They send them down to their root systems to give their fungi friends a little pep up.
But there’s no such thing as a free lunch. Mushrooms have to hold up their end of the bargain…
Plants have a limited ability to absorb nutrients through their roots. Thankfully, mushroom mycelium has a higher absorption capacity for water and nutrients than plant roots. So, by connecting with fungi, plants can unlock a whole range of hard-to-reach soil nutrients, including nitrogen, phosphorus, magnesium and iron. It's no wonder between 80 - 90% of plants are believed to form mycorrhiza!
But before we go any further, it’s important to note that mycorrhiza is only one of many fungi-plant relationships. It’s not always rainbows and butterflies. There are some parasitic and exploitative relationships – which means that either the plant or fungus will thrive at the expense of the other. But thankfully, this is far less common than a mutualistic, ‘everybody-wins’ type of arrangement.
Types Of Mycorrhiza
There are two main types of Mycorrhiza: Ectomycorrhiza and Endomycorrhiza (try reading that sentence fast). Ecotmycorrhiza refers to fungi that externally latch onto the plant root. They typically make up around 10% of mutualistic associations – and are commonly found on Birch and Pine trees.
Endomycorrhiza on the other hand form their relationship within the cells of the plant roots (in other words, the fungus grows inside the root cells). This relationship is far more common – believed to occur around 85% of plant species!
3 Plant Benefits Of Mycorrhiza
Protect against disease
When plants are first becoming established, they’re more susceptible to root and soil-borne diseases. Although studies suggest that early mycorrhizal associations can prevent disease and help plants thrive. This is because plants with a healthy mycorrhizal relationship are well nourished and stronger - and the mycorrhizal relationship also helps them to excrete toxic enzymes to kill off disease! What’s more, many scientists believe that mycorrhiza may be an effective and environmentally friendly alternative to traditional plant disease control (you know, the ones that are loaded with chemicals).
Increase plant tolerance to drought
Mycorrhizal relationships can also help plants survive during drought. Mycorrhizal plants adapt to drought stress as the mushroom mycelium creates more opportunities for water and mineral uptake. The plant's limited root system is extended by the fungi’s ability to sweep the forest floor looking for nutrients. And in a drought-prone country like Australia, we find this benefit particularly fascinating.
Protect plants against insects
Here’s the incredible part – it’s widely believed that plants talk to each other through the underground, mycelium root system. What are they saying, you might be wondering? As it turns out, a whole lot of useful stuff! The underground root system can warn neighbouring plants of insect attacks. And then, the plant has time to prepare its defences. Once getting word of the impending insects, the plant releases special compounds that attract the insect’s predators. Mushrooms save the day, once again.
The Miracle of Mycorrhizal Relationships
The humble fungus rarely shows its face. A quiet achiever for most of the time – but let’s not forget that it’s responsible for life as we know it. Mycorrhizal association can control soil erosion, improve drought tolerance and create healthy plant life. And when our plants thrive – there are flow-on effects for all species.
Not only that, mycorrhiza relationships can help to feed the world by acting as a biofertilizer and insect repellent. Yep, the relationship between fungi and plants might be the saving grace our planet needs.