Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Republic of Korea.
Division of Biotechnology, The Catholic University of Korea, Bucheon 14662, Republic of Korea.
Plant Physiol. 2022 May 3;189(1):360-374. doi: 10.1093/plphys/kiac062.
A-type ATP-binding cassette (ABCA) proteins transport lipids and lipid-based molecules in humans, and their malfunction is associated with various inherited diseases. Although plant genomes encode many ABCA transporters, their molecular and physiological functions remain largely unknown. Seeds are rapidly developing organs that rely on the biosynthesis and transport of large quantities of lipids to generate new membranes and storage lipids. In this study, we characterized the Arabidopsis (Arabidopsis thaliana) ABCA10 transporter, which is selectively expressed in female gametophytes and early developing seeds. By 3 d after flowering (DAF), seeds from the abca10 loss-of-function mutant exhibited a smaller chalazal endosperm than those of the wild-type. By 4 DAF, their endosperm nuclei occupied a smaller area than those of the wild-type. The endosperm nuclei of the mutants also failed to distribute evenly inside the seed coat and stayed aggregated instead, possibly due to inadequate expansion of abca10 endosperm. This endosperm defect might have retarded abca10 embryo development. At 7 DAF, a substantial portion of abca10 embryos remained at the globular or earlier developmental stages, whereas wild-type embryos were at the torpedo or later stages. ABCA10 is likely involved in lipid metabolism, as ABCA10 overexpression induced the overaccumulation of triacylglycerol but did not change the carbohydrate or protein contents in seeds. In agreement, ABCA10 localized to the endoplasmic reticulum (ER), the major site of lipid biosynthesis. Our results reveal that ABCA10 plays an essential role in early seed development, possibly by transporting substrates for lipid metabolism to the ER.
A 型 ATP 结合盒（ABC）蛋白在人体中运输脂质和基于脂质的分子，其功能障碍与各种遗传性疾病有关。尽管植物基因组编码了许多 ABCA 转运蛋白，但它们的分子和生理功能在很大程度上仍然未知。种子是快速发育的器官，依赖于大量脂质的生物合成和运输，以产生新的膜和储存脂质。在这项研究中，我们对拟南芥（Arabidopsis thaliana）ABCA10 转运蛋白进行了表征，该蛋白选择性地在雌性配子体和早期发育的种子中表达。开花后 3 天（DAF），abca10 功能丧失突变体的种子比野生型的胚珠端胚乳小。到 4 DAF，其胚乳核的面积比野生型的小。突变体的胚乳核也未能均匀分布在种皮内，而是聚集在一起，可能是由于 abca10 胚乳的扩张不足。这种胚乳缺陷可能阻碍了 abca10 胚胎的发育。在 7 DAF，大量的 abca10 胚胎仍然处于球形或更早的发育阶段，而野生型胚胎处于鱼雷形或更晚的阶段。ABCA10 可能参与脂质代谢，因为 ABCA10 的过表达诱导了三酰基甘油的过度积累，但没有改变种子中的碳水化合物或蛋白质含量。同样，ABCA10 定位于内质网（ER），这是脂质生物合成的主要场所。我们的结果表明，ABCA10 在早期种子发育中发挥着重要作用，可能是通过将脂质代谢的底物运输到 ER 来实现的。
