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

谷类作物采用复杂的运输系统来获取和分配矿质营养素，并在细胞和整个植株水平上维持营养平衡，这是谷物平衡生长、种子生产和营养成分的先决条件。尽管在模式作物水稻中已经发现了几种矿质元素的膜转运体，但通过生物强化提高谷物营养积累的基于知识的方法仍处于起步阶段。利用IPK基因库中大麦种子营养性状的全基因组关联图谱，我们已经确定了迄今为止尚未确定的金属转运基因MTP1的等位基因变异；2、这与大麦籽粒锌、铁、锰的差异积累有关。我们的初步工作表明，MTP1的基因编辑；2改变锌在节点和籽粒中的积累。因此，建议项目的总体目标是充分探索HvMTP1的功能作用；2及其在节点微量元素储存和籽粒微量元素分配上的自然变异。通过将遗传和分子与经典植物营养方法相结合，我们将i)验证已确定的候选基因MTP1之间的因果关系；2、谷物中锌等金属的积累；ii)确定HvMTP1的表达模式和功能作用；2在大麦中的作用及其等位基因变异对大麦籽粒微量营养素积累的贡献；iii)采用改良MTP1的大麦品系；2表达，揭示MTP1的重要性；2和2个节点，用于微量营养素的储存、分配和解毒，以及器官发育和生物强化。

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.