The Universities of Cambridge and Bordeaux plant scientists have discovered a gene that they hope can be used to widen a nutrient trafficking bottleneck and potentially increase crop yields.
Around the world, plant scientists are working on several different strategies to increase crop yields sustainably. One of the approaches that could contribute to this next Green Revolution is to increase the efficiency of how plants transport sugars, protein, and other organic nutrients between different parts of the plant.
Biotechnologists will be able to breed more productive crops in the future when they have an understanding of factors that affect local and long distance transport within a plant. Ultimately, it might be possible to direct the traffic of organic nutrients to specific parts of the plants that are harvested (seeds, fruits, and storage tubers).
Research team of Professor Yrjo Helariutta at the Sainsbury Laboratory Cambridge University (SLCU) and Dr. Emmanuelle Bayer's group at the University of Bordeaux/CNRS have brought this goal a step closer by discovering Phloem Unloading Modulator (PLM), a new gene that affects nutrient trafficking by altering the channels connecting neighboring plant cells called plasmodesmata. These nanoscale membrane-lined channels traverse the cell wall barrier to link plant cells together and enable the transfer of essential substances.
The team published the result of the study in Nature Plants and it reveals that Arabidopsis thaliana mutant plants missing the PLM gene were discovered to release more substances from the phloem (a specialized tissue for long distance transport) at the tips of their roots: using a fluorescent protein as a proxy for macromolecules, the scientists could see that the PLM gene was having a definite controlling effect on the amount of phloem unloading. To find out how the gene was doing this, the researchers looked at what was happening at different cells interfaces in the roots of seeding plants.
Dr. Dawei Yan, the lead author from Cambridge's Sainsbury Laboratory, explained that they discovered that mutating PLM relieves a trafficking bottleneck, that was previously reducing the outward movement of nutrients from the vascular system to the rapidly growing tissues in the roots.
Exclusively, PLM is acting at the interface between the phloem pole pericycle (PPP) and endodermal cells, an interface essential for the radial movement of substances after unloading. Removing PLM gene activity could enable plants to more rapidly and efficiently transport nutrients to where they are needed. The roots in the mutant plants grew faster and longer as a result of the increased unloading.
In some molecular and genetic investigations, it was revealed that PLM is involved in the biosynthesis of sphingolipids, which are a class of lipids connected with plant development and response to the environment. Though the team of Dr. Bayer had previously shown that sphingolipids enriched the membranes of plasmodesmata, this is the first research to connect sphingolipids to plasmodesmata function.
