The research, published in Nature, describes how the scientists engineered the sensor in the model plant Arabidopsis thaliana.
Plants, like animals, have hormones that regulate how they grow and develop. Plant hormones give their shape to plants, cause tomatoes to ripen, leaves to drop and roots to grow downwards. Auxin is essential for plant body development. It has a key role in the coordination of many growth and behavioural processes in a plant’s life cycle, from embryo patterning, to regulation of leaf and root growth and even the shape of flowers.
The new sensor, dubbed DII-VENUS, can monitor rapid changes in auxin and allowed researchers to visualise, almost in real-time, the redistribution of auxin during developmental responses. This has revealed much more complex patterns of auxin in tissues than previously thought, indicating that sensitivity to the hormone within tissues precisely control their capacity to respond.
Malcolm Bennett, professor of plant sciences in the School of Biosciences and Biology and the director at the Centre for Plant Integrative Biology (CPIB), told The Engineer the sensor could be described as a ’protein sensor’.
’It is essentially a piece of repressor protein attached to a jellyfish protein called Green Fluorescent Protein (GFP),’ he said.
’We had to use a very special version of GFP called Venus because these repressor proteins are very unstable.
’The problem up till now is that people have been using normal forms of GFP and this is a protein which takes about two hours to mature so if whatever you’re trying to tag is being degraded in a matter of minutes…it’s never going to work.’
Bennett and his team used a fast-folding version of GFP that matures in minutes and he claims this was the real breakthrough.
A low auxin presence is indicated by an accumulation of the sensor while a high auxin presence is indicated by an absence of the sensor.
The sensor could be used to determine exactly where and when auxin accumulates in plant tissues and could help scientists to design plants with new shapes, sizes and properties.
With funding from the Biotechnology and Biological Sciences Research Council (BBSRC) and the Engineering and Physical Sciences Research Council (EPSRC), the auxin sensor was developed and characterised by scientists led by CNRS Researcher Dr Teva Vernoux from the Laboratoire de Reproduction et Développement des Plantes (RDP) at Lyon University in collaboration with the CPIB at Nottingham University, the Department of Plant systems Biology, VIB, at Ghent University and the Centre for Plant Science at Leeds University.
Dr Vernoux said: ‘We can now visualise auxin in living tissues. This is fantastic progress for the understanding of the role of hormones in plant development.’