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A research team led by Prof. Cao Xiaofeng from the Institute of Genetics and Developmental Biology (IGDB) of the Chinese Academy of Sciences has uncovered a key translational regulatory mechanism governing the seed-to-seedling transition.

The study, published in , provides critical insights into how plants control germination at the molecular level.

Seed dormancy and germination are critical phases during plant development. Germination marks the transition from dormancy to active growth, regulated by internal hormonal signals, such as the antagonistic interplay between abscisic acid (ABA) and gibberellin (GA); and external cues, like light, temperature, and moisture.

Preharvest sprouting (PHS), where seeds germinate prematurely on the spike due to insufficient dormancy, leads to significant yield losses in cereal crops worldwide. Therefore, understanding the molecular mechanisms governing seed dormancy and germination is essential for improving crop resilience and safeguarding food security.

Recent studies emphasize the role of stored mRNA translation during early germination. While mRNA molecules contain specific cis-regulatory elements that modulate translation, their specific roles in seed germination remain less explored.

In this study, Prof. Cao's team employed integrated transcriptomic and translatomic analyses to systematically dissect the dynamic regulation of gene expression during germination.

Using ribosome-defective mutants, the researchers demonstrated that their delayed germination is linked to ABA2, a key gene in ABA biosynthesis. The 5′ UTR of ABA2 harbors an upstream open reading frame (uORF) that represses translation of the downstream coding sequence (CDS).

Further investigation revealed that this regulatory mechanism is highly conserved in rice. CRISPR-Cas9-mediated knockout of the uORF in OsABA2 effectively suppressed PHS. Additionally, they identified two major uORF haplotypes in rice cultivars that modulate PHS resistance by fine-tuning OsABA2 expression.

These findings provide fundamental insights into how translational regulation and natural genetic variation coordinate seed dormancy and germination, simultaneously offering practical molecular strategies for crop improvement.