Title: Restriction of Iron Loading into Developing Seeds by A YABBY Transcription Factor Safeguards Successful Reproduction in Arabidopsis

Li Sun, Yun Qi Wei, Kang Hao Wu, Jing Ying Yan, Jie Na Xu, Yun Rong Wu, Gui Xin Li, Ji Ming Xu, Nicholas P. Harberd, Zhong Jie Ding, Shao Jian Zheng

Published: June 07, 2021

DOI: https://doi.org/10.1016/j.molp.2021.06.005

Abstract

Iron (Fe) storage in plant seeds is not only necessary for seedling establishment following germination, but also a major source of dietary Fe for human and animal life. Seed Fe accumulation was known to be low during early seed development. However, the underlying mechanism and biological significance remain elusive. Here, we show that reduced expression of Arabidopsis YABBY transcription factor INNER NO OUTER (INO) increases embryonic Fe accumulation, while transgenic overexpression of INO has opposite effect. INO is highly expressed during early seed development, and that decreased expression of INO increases the expression of NATURAL RESISTANCE ASSOCIATED MACROPHAGE PROTEIN 1 (NRAMP1), a gene encoding a transporter contributing to Fe loading into the seed. The relatively high embryonic Fe accumulation conferred by decreased expression of INO is rescued by the nramp1 loss-of-function mutation. We further demonstrate that INO represses NRAMP1 expression by binding to NRAMP1 specific promoter region. Moreover, we show that excessive Fe loading into developing seeds in ino mutants produces more oxidative damage, leading to increased cell death and seed abortion, a phenotype that can be rescued by nramp1 mutation. Taken together, these results indicate that INO plays an important role in safeguarding reproduction by reducing Fe loading into developing seeds via repression of NRAMP1 expression.

Link:  https://www.cell.com/molecular-plant/fulltext/S1674-2052(21)00217-3

More: Mechanism and biological significance of regulating iron loading during early seed development