Plants need to take up sufficient levels of the essential nutrient phosphate (P) from the soil to grow. To increase their surface area to take up more P from the soil, plants elongate root hairs. New research from the University of Nottingham and a multinational team of collaborators reveals how this process works, opening the way to create improved varieties of crops.
The research - “Rice auxin influx carrier OsAUX1 facilitates root hair elongation in response to low external phosphate” and “ A mechanistic framework for auxin dependent Arabidopsis root hair elongation to low external phosphate ” - has discovered that low soil phosphate levels increase levels of the plant hormone auxin and that this promotes root hair elongation. The team has also identified several key genes that control root hair elongation. Their findings have been published in papers.
The research was originally started in rice where team members observed that disrupting the auxin transport protein OsAUX1 gene blocked root hair elongation in response to low soil phosphate. They later discovered that the auxin induced root hair growth response was also found in distantly related plant species. This led the team to conclude that the root hair growth response to low soil P and auxin was highly conserved across the plant kingdom.
Using innovative x-ray CT and laser imaging techniques the inter-disciplinary team of scientists (drawn from plant, crop, soil and computer sciences) were able to reveal how roots grow and develop in soil, forage for nutrients and adapt to changing conditions. These images showed that when the plant hormone auxin increased so did the elongation of the root hairs.
Professor Malcolm Bennett led the study and explains why the discovery is so important: “Food security represents a pressing global issue. Crop production must double by 2050 to keep pace with global population growth. This target is even more challenging given the impact of climate change on water availability and the drive to reduce fertilizer inputs to make agriculture become more environmentally sustainable. In both cases, developing crops with improved water and nutrient uptake efficiency would provide a solution.
Very few genes that regulate root architectural traits such as root hairs have been identified in crops so it is very exciting that our team and our collaborators are making new discoveries in this area. We plan to translate this fundamental knowledge to re-engineer root traits and optimise yields in crops relevant to Europe (wheat), Asia (rice) and Africa (pearl millet) in collaboration with teams based in these countries and continents.”
Professor Bennett concludes: “Now we understand more about the hormone signals and genes which affect root hair growth we can look at which combinations are required for crop improvement to underpin global food security efforts. These efforts are being supported by an inter-disciplinary research programme supported by the University of Nottingham Future Food Beacon of Research Excellence and a wide range of other UK and international funding organisations.”