Auxin: Hormonal Signal Required for Seed Development and Dormancy

TL;DR

This review highlights the role of auxin in seed development and dormancy, showing how it works with other hormones like ABA.

Contribution

The paper emphasizes the newly recognized essential role of auxin in seed development and dormancy regulation.

Findings

Auxin is crucial for endosperm and seed-coat development through its synthesis and transport.

AGL62 regulates auxin transport from the endosperm, impacting integuments development.

Auxin interacts with ABA signaling, with ABI3 playing a key role in primary dormancy.

Abstract

The production of viable seeds is a key event in the life cycle of higher plants. Historically, abscisic acid (ABA) and gibberellin (GAs) were considered the main hormones that regulate seed formation. However, auxin has recently emerged as an essential player that modulates, in conjunction with ABA, different cellular processes involved in seed development as well as the induction, regulation and maintenance of primary dormancy (PD). This review examines and discusses the key role of auxin as a signaling molecule that coordinates seed life. The cellular machinery involved in the synthesis and transport of auxin, as well as their cellular and tissue compartmentalization, is crucial for the development of the endosperm and seed-coat. Thus, auxin is an essential compound involved in integuments development, and its transport from endosperm is regulated by AGAMOUS-LIKE62 (AGL62) whose transcript is specifically expressed in the endosperm. In addition, recent biochemical and genetic evidence supports the involvement of auxins in PD. In this process, the participation of the transcriptional regulator ABA INSENSITIVE3 (ABI3) is critical, revealing a cross-talk between auxin and ABA signaling. Future experimental aimed at advancing knowledge of the role of auxins in seed development and PD are also discussed.

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