Department of Soil and Crop Sciences, Texas A&M University and Texas A&M AgriLife Research, College Station, TX, USA.
Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX, 77843, USA.
Sci Rep. 2022 Jan 10;12(1):348. doi: 10.1038/s41598-021-04284-7.
Wheat grain protein content and composition are important for its end-use quality. Protein synthesis during the grain filling phase is supported by the amino acids remobilized from the vegetative tissue, the process in which both amino acid importers and exporters are expected to be involved. Previous studies identified amino acid importers that might function in the amino acid remobilization in wheat. However, the amino acid exporters involved in this process have been unexplored so far. In this study, we have curated the Usually Multiple Amino acids Move In and out Transporter (UMAMIT) family of transporters in wheat. As expected, the majority of UMAMITs were found as triads in the A, B, and D genomes of wheat. Expression analysis using publicly available data sets identified groups of TaUMAMITs expressed in root, leaf, spike, stem and grain tissues, many of which were temporarily regulated. Strong expression of TaUMAMITs was detected in the late senescing leaves and transfer cells in grains, both of which are the expected site of apoplastic amino acid transport during grain filling. Biochemical characterization of selected TaUMAMITs revealed that TaUMAMIT17 shows a strong amino acid export activity and might play a role in amino acid transfer to the grains.
小麦籽粒的蛋白质含量和组成对其食用品质至关重要。籽粒灌浆期的蛋白质合成依赖于从营养组织中重新分配的氨基酸，在此过程中，预计氨基酸的输入和输出都将参与其中。先前的研究已经确定了可能在小麦氨基酸再利用过程中起作用的氨基酸输入器。然而，到目前为止，参与这一过程的氨基酸输出器尚未被探索。在这项研究中，我们对小麦中的通常多氨基酸进/出转运蛋白（UMAMIT）家族的转运蛋白进行了分类整理。正如预期的那样，大多数 UMAMIT 在小麦的 A、B 和 D 基因组中被发现为三联体。使用公开可用的数据集进行表达分析，鉴定了在根、叶、穗、茎和籽粒组织中表达的 TaUMAMIT 基因群，其中许多基因是暂时调控的。在籽粒灌浆过程中，即将衰老的叶片和传递细胞中检测到 TaUMAMIT 的强烈表达，这两个部位都是质外体氨基酸运输的预期部位。对选定的 TaUMAMIT 的生化特性分析表明，TaUMAMIT17 表现出较强的氨基酸输出活性，可能在向籽粒中转运氨基酸方面发挥作用。
