AUTHOR=Hussain Shah , Kim Sun Ho , Bahk Sunghwa , Ali Akhtar , Nguyen Xuan Canh , Yun Dae-Jin , Chung Woo Sik 

TITLE=The Auxin Signaling Repressor IAA8 Promotes Seed Germination Through Down-Regulation of ABI3 Transcription in Arabidopsis

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.00111

DOI=10.3389/fpls.2020.00111

ISSN=1664-462X

ABSTRACT=<p>Seed germination is a complex biological process controlled by various regulators, including phytohormones. Among these, abscisic acid and gibberellic acid inhibit and promote seed germination, respectively. Many studies have addressed the biological roles of auxin in plant growth and development, but very few have considered its role in seed germination. Here, we identified a novel function of the auxin signaling repressor Aux/IAA8 during seed germination. The <italic>IAA8</italic> loss-of-function mutant <italic>iaa8-1</italic> exhibited delayed seed germination. The phenotype of <italic>iaa8-1</italic> was restored by ectopic expression of <italic>IAA8</italic>. Interestingly, IAA8 accumulated to high levels during seed germination, which was achieved not only by increased protein synthesis but also by the stabilization of IAA8 protein. We also showed that IAA8 down-regulates the transcription of <italic>ABSCISIC ACID INSENSITIVE3</italic> (<italic>ABI3</italic>), a negative regulator of seed germination. Our study, thus strongly suggest that the auxin signaling repressor IAA8 acts as a positive regulator of seed germination in <italic>Arabidopsis thaliana</italic>.</p>