RIKEN Center for Sustainable Resource Science, Kanagawa, Japan.
Graduate school of Science and Technology, Nara Institute of Science and Technology, Nara, Japan.
Plant Signal Behav. 2022 Dec 31;17(1):2095488. doi: 10.1080/15592324.2022.2095488.
Abscisic acid (ABA) is a plant hormone that induces seed dormancy during seed development and inhibits seed germination after imbibition. Although ABA is synthesized in the seed coat (testa), endosperm, and embryo, the physiological roles of the hormone derived from each tissue are not fully understood. We found that the gene encoding an Arabidopsis ABA importer, , was expressed in the seed coat during seed development. Dry seeds of loss-of-function mutants contained significantly higher levels of dihydrophaseic acid (DPA), an inactive ABA metabolite, than the wild type. The mutant also had a slight increase in ABA content. An increase in DPA was prominent in the fraction containing the seed coat and endosperm. Seed germination of the mutant was similar to the wild type in the presence of ABA or the gibberellin biosynthesis inhibitor paclobutrazol. However, a mutation in suppressed the paclobutrazol-resistant germination of , a mutant impaired in an ABA importer expressed in the embryo. These results suggest that ABA uptake into the seed coat mediated by NPF5.1 is important for ABA homeostasis during seed development and for regulating seed germination.
脱落酸（ABA）是一种植物激素，它在种子发育过程中诱导种子休眠，并在吸胀后抑制种子萌发。尽管 ABA 是在种皮（种壳）、胚乳和胚中合成的，但该激素来源于每个组织的生理作用尚未完全了解。我们发现，拟南芥 ABA 导入器的基因 ，在种子发育过程中种皮中表达。功能丧失 突变体的干种子比野生型含有显著更高水平的二氢相位酸（DPA），一种非活性 ABA 代谢物。 突变体的 ABA 含量也略有增加。DPA 的增加在包含种皮和胚乳的部分中很明显。在 ABA 或赤霉素生物合成抑制剂多效唑存在下， 突变体的种子萌发与野生型相似。然而，在表达于胚中的 ABA 导入器的 突变体中， 突变抑制了多效唑抗性萌发。这些结果表明，由 NPF5.1 介导的 ABA 向种皮的摄取对于种子发育过程中的 ABA 动态平衡以及调节种子萌发很重要。
