2025-06-06 中国科学院(CAS)
The working model of ABA2 uORF (Image by IGDB)
<関連情報>
- https://english.cas.cn/newsroom/research_news/life/202506/t20250611_1045403.shtml
- https://www.pnas.org/doi/10.1073/pnas.2502155122
ABSCISIC ACID DEFICIENT2の上流オープンリーディングフレームによる種子から苗木への移行の制御 Control of seed-to-seedling transition by an upstream open reading frame in ABSCISIC ACID DEFICIENT2
Zhen Wang, Xiaofan Zhang, Can Zhou, and Xiaofeng Cao
Proceedings of the National Academy of Sciences Published:June 6, 2025
DOI:https://doi.org/10.1073/pnas.2502155122
Significance
Seed dormancy and germination are critical phases during plant development. The hormone abscisic acid (ABA) has important roles in seed dormancy, and ABA DEFICIENT2 (ABA2) acts in ABA biosynthesis. Here, we revealed a translational regulation of ABA during seed-to-seedling transition, we found that an upstream open reading frame (uORF) in the ABA2 messenger RNA (mRNA) affects its translation in rice and Arabidopsis. Notably, we found that nucleotide variations in the uORF sequence of OsABA2 among rice cultivars lead to distinct preharvest sprouting phenotypes. This work underscores the significant role of ABA2 uORF in seed biology and offers promising strategies for crop improvement.
Abstract
The start of seed germination is a major decision point in plant life cycle, which relies on seed stored mRNA. However, the underlying translational mechanism remains less illustrated. Here, we demonstrate that inhibiting translation using translation inhibitors and ribosome-defective mutants delays germination in Arabidopsis. Through comprehensive transcriptome deep sequencing (RNA-seq) and polysome profiling analyses, we elucidated the dynamic interplay of regulation at the transcriptional and translational levels during germination. We show that delayed germination in some ribosome-defective mutants is partially regulated by the gene ABSCISIC ACID DEFICIENT2 (ABA2), with an upstream open reading frame (uORF) in the 5′ untranslated region that represses translation of the downstream ORF encoding ABA2. In addition, disrupting rice OsABA2 uORF inhibited preharvest sprouting (PHS). Furthermore, we found two main haplotypes for the uORF among rice cultivars that result in different OsABA2 expression levels, thus contributing to diverse PHS phenotypes. This work highlights the critical role of translational control and genetic variation in seed dormancy and germination, with implications for crop improvement.
