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

谷类作物物种采用复杂的运输系统来获取和分配矿物质营养素，并在细胞以及整株植物水平上维持营养稳态，这是平衡生长、种子生产和谷物中营养成分的先决条件。虽然已经在模式作物水稻中确定了几种矿物元素的膜转运蛋白，但通过谷物中的生物强化来提高营养积累的基于知识的方法仍处于起步阶段。采用全基因组关联映射的种子营养性状在大麦加入从IPK基因库，我们已经确定了等位基因变异，迄今为止未表征的金属转运蛋白基因MTP 1;2，这涉及到差异锌，铁，锰积累在大麦籽粒。我们的初步工作表明，MTP 1;2的基因编辑改变了节点和籽粒中的锌积累。因此，拟议项目的总体目标是充分探索HvMTP 1的功能作用;2和它的自然变化的微量营养素存储节点和微量营养素分配到大麦籽粒。通过遗传学、分子生物学和经典植物营养学方法相结合，我们将i）验证已鉴定的候选基因MTP 1;2与籽粒中锌和其它金属积累之间的因果关系，ii）确定HvMTP 1;2在大麦中的表达模式和功能作用以及其等位基因变异对大麦籽粒中微量营养素积累的贡献;和iii）使用具有修饰的MTP 1;2表达的大麦品系以揭示MTP 1;2和节点对于微量营养素储存、分配和解毒以及对于器官发育和生物强化的重要性。

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.