Unlocking and employing genetic variation of the metal transporter HvMTP1;2 in stem nodes for improved organ development, micronutrient allocation and biofortification in barley

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Cereal crop species employ complex transport systems to acquire and allocate mineral nutrients and to maintain nutrient homeostasis at the cellular as well as at the whole-plant level as prerequisite for balanced growth, seed production and nutrient composition in the grain. Although several membrane transporters for mineral elements have been identified in the model crop rice, knowledge-based approaches to improve nutrient accumulation via biofortification in cereal grains are still in their infancy. Employing genome-wide association mapping of seed nutrient traits in barley accessions from the IPK gene bank, we have identified allelic variation in the so far uncharacterized metal transporter gene MTP1;2, which relates to differential zinc, iron and manganese accumulation in barley grains. Our preliminary work shows that gene editing of MTP1;2 alters zinc accumulation in nodes and in grains. Thus, the overall goal of the proposed project is to fully explore the functional role of HvMTP1;2 and its natural variation for micronutrient storage in nodes and for micronutrient allocation to barley grains. By combining genetic and molecular with classical plant nutritional approaches we will i) verify causality between the identified candidate gene MTP1;2 and the accumulation of zinc and other metals in the grain; ii) determine the expression pattern and functional role of HvMTP1;2 in barley as well as the contribution of its allelic variation to micronutrient accumulation in barley grains; and iii) employ barley lines with modified MTP1;2 expression to reveal the importance of MTP1;2 and of nodes for micronutrient storage, allocation and detoxification as well as for organ development and biofortification.