Plant Science

Blushing plants reveal fungi in their roots

Scientists creates plants whose cells and tissues ‘blush’ with beetroot pigments when they are colonised by fungi

September 22, 2021
The Scitech
 

Almost all crop plants form associations with a particular type of fungi – called arbuscular mycorrhiza fungi – in the soil, which greatly expand their root surface area. This mutually beneficial interaction boosts the plant’s ability to take up nutrients that are vital for growth.  In a study published in the journal PLOS Biology, researchers used the bright red pigments of beetroot – called betalains – to visually track soil fungi as they colonised plant roots in a living plant.  “We can now follow how the relationship between the fungi and plant root develops, in real-time, from the moment they come into contact. We previously had no idea about what happened because there was no way to visualise it in a living plant without the use of elaborate microscopy,” said Dr Sebastian Schornack, a researcher at the University of Cambridge’s Sainsbury Laboratory and joint senior author of the paper.  To achieve their results, the researchers engineered two model plant species – a legume and a tobacco plant – so that they would produce the highly visible betalain pigments when arbuscular mycorrhiza fungi were present in their roots. This involved combining the control regions of two genes activated by mycorrhizal fungi with genes that synthesise red-coloured betalain pigments. The plants were then grown in a transparent structure so that the root system was visible, and images of the roots could be taken with a flatbed scanner without disturbing the plants. Using their technique, the researchers could select red pigmented parts of the root system to observe the fungus more closely as it entered individual plant cells and formed elaborate tree-like structures – called arbuscules – which grow inside the plant’s roots. Arbuscules take up nutrients from the soil that would otherwise be beyond the reach of the plant. 

 “This is an exciting new tool to visualise this, and other, important plant processes. Beetroot pigments are a distinctive colour, so they’re very easy to see. They also have the advantage of being natural plant pigments, so they are well tolerated by plants,” said Dr Sam Brockington, a researcher in the University of Cambridge’s Department of Plant Sciences, and joint senior author of the paper. Understanding and exploiting the dynamics of plant root system colonisation by fungi has potential to enhance future crop production in an environmentally sustainable way. If plants can take up more nutrients naturally, this will reduce the need for artificial fertilisers – saving money and reducing associated water pollution. 

Source: University of Cambridge news release