Nutrient impacts on plant secretions into soil

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Collaborative work in the Field and Knox laboratories has discovered that plant roots and rhizoids secrete high molecular weight glycans (polysaccharides) and that some of these are potent aggregators of soil particles. Aggregation of mineral particles is a key factor in soil formation and soil health. These important discoveries are in preparation for publication. Recent work by the two groups has also discovered that the profiles of secreted glycans are modulated by nutrient regimes. Currently we know that the lack of all nutrients leads to the specific upregulation of the soil aggregating glycan. This project will determine how varying nutrient regimes will impact on profiles of secreted glycans determined using quantitative methods with sets of monoclonal antibodies and carbohydrate-binding modules with high specificities and sensitivities. A key objective will be the identification of the specific nutrients that influence the secretion of glycans and the dissection of the underlying mechanistic physiology. The project will encompass species from across the land plant phylogeny and study glycan release from bryophyte rhizoids (a colonizing class of plants, important in soil formation in disturbed ground) and also utilize arabidopsis (genetic model with unparalleled resources to dissect mechanistic pathways) and wheat (a major crop species). Growth systems will include solid agar media (for bryophytes and Arabidopsis) and hydroponic systems (wheat). This is both a novel and timely project as studies on the structure and functions of high molecular weight molecules released by plant rhizoids and roots is a severely neglected area due to the lack of sensitive glyco-molecular tools. These tools are now available in the Knox laboratory. It is also extremely timely as loss of soil structure and poor soil health are major global problems impacting on crop productivity. Current molecular understanding of how plants can influence soil properties is scant