Mode of action of biosourced phytostimulants on a multi-stress signalling pathway – BioPhyt

Measure the effect of Roullier phytostimulants (NatMols) on :

# Root growth, root exudation of organic acids and expression of marker genes of the STOP1 signalling pathway, in Arabidopsis and cultivated species ;
# Parietal hardening of the root tip cells in Arabidopsis.
# Identifying mutants of Arabidopsis affected in their susceptibility to a NatMol.

Partner 1 :
The effect of NatMols on root growth in -Pi and on the expression of markers (qRT-PCR and visual marker) of the STOP1 pathway of Arabidopsis was tested three times. The results are reproducible. In summary, 6 NatMols improve root growth (20 to 80% of the +Pi control).
One NatMol has a (modest) effect on the STOP1 signalling pathway.

Partner 2 :
In collaboration with partner 1, a protocol for the analysis and measurement of organic acids exuded by Arabidopsis has been developed on the metabolomics platform of the World Innovation Centre (WIC).


Partner 3 :
A new innovative computer programme for analysing AFM (Atomic Force Microscopy) results has been created. This programme is currently being tested.
A PhD student (outside of the ANR project) has tested a wide range of Arabidopsis seedling deposit/maintenance systems to make nanomechanical measurements.
Finally, to better guide the nanomechanical measurement protocol with the atomic force microscope, scanning electron imaging in environmental mode (ESEM) was carried out at the CERMAV in Grenoble in order to better understand the topology of Arabidopsis epidermal root cells. From this imagery we concluded that it is necessary to make measurements at least 5 µm apart to avoid falling on cell interfaces that present very different topological properties from the cell faces on the root surface. A new measurement protocol is currently being finalised.

The effect of NatMols on the exudation of organic acids by Arabidopsis seedlings and the different cultivated species will start in October 2020.
AFM analyses on Arabidopsis seedlings treated with NatMol will start in 2021.

Godon C, Kaur H, Teulon J-M, Chen SWW, Desnos T and Pellequer J-L (2020?) Plant root cell wall stiffening induced by a metallic stress. In Mechanics in Diseases. Radmacher M, Lekka M, Navajas D and Podestà A (eds), submitted.

Kaur H, Godon C, Teulon J-M, Desnos T and Pellequer J-L (2020?) Preparation and deposition of plant roots for AFM nanomechanical measurements. In Mechanics in Diseases. Radmacher M, Lekka M, Navajas D and Podestà A (eds), submitted.

A major challenge of the coming years is to reduce environmental impacts of agriculture while maintaining, if not increasing, crop yields. One solution to reduce fertilizer inputs is to increase the efficiency of crops using them, for example by increasing root growth and resistance to abiotic stresses.
Phytostimulants are molecular effectors that when used in small quantities boost plant growth, in particular the root system. Knowing how phytostimulants work in plants could greatly help to use them more rationally, and assess their safety to environment. In any case, this knowledge is frequently asked to obtain marketing authorisation, as for any new agrochemical.

The private partner has identified biosourced phytostimulants improving resistance to abiotic stress, root growth, N, S and P contents and increase yields in crops such as rapeseed, pea, soybean and maize. Interestingly, some of these phytostimulants also improve the Arabidopsis root growth in phosphate deficiency condition.

The aim of this project is to:
1) Understand how the biosourced phytostimulants improve crop rooting and yields, in particular under abiotic stress;

2) Use these biosourced phytostimulants as new tools to study a multi-stress signalling pathway of Arabidopsis;

Through 6 tasks, a private company and two academic partners will collaborate in physiology, genetics, molecular biology, biochemistry, biophysics and metabolomic experiments in order to reach these three aims.