Gibberellin signaling regulates lignin biosynthesis to modulate rice seed shattering

The elimination of seed shattering was a key step in rice (Oryza sativa) domestication. In this paper, we show that increasing the gibberellic acid (GA) content or response in the abscission region enhanced seed shattering in rice. We demonstrate that SLENDER RICE1 (SLR1), the key repressor of GA signaling, could physically interact with the rice seed shattering-related transcription factors quantitative trait locus of seed shattering on chromosome 1 (qSH1), O. sativa HOMEOBOX 15 (OSH15), and SUPERNUMERARY BRACT (SNB). Importantly, these physical interactions interfered with the direct binding of these three regulators to the lignin biosynthesis gene 4-COUMARATE: COENZYME A LIGASE 3 (4CL3), thereby derepressing its expression. Derepression of 4CL3 led to increased lignin deposition in the abscission region, causing reduced rice seed shattering. Importantly, we also show that modulating GA content could alter the degree of seed shattering to increase harvest efficiency. Our results reveal that the Green Revolution phytohormone GA is important for regulating rice seed shattering, and we provide an applicable breeding strategy for high-efficiency rice harvesting. DELLA protein SLR1 interacts with 3 shattering transcription factors (qSH1, OSH15, and SNB) to alter lignin biosynthesis and regulate seed shattering in rice (Oryza sativa).

Automated summary

This study demonstrates the importance of gibberellic acid (GA) in regulating seed shattering in rice. By increasing the GA content or response, seed shattering can be enhanced. The interaction between the repressor SLR1 and shattering-related transcription factors affects lignin biosynthesis, leading to reduced seed shattering. Moreover, modulating GA content can be useful for improving rice harvesting efficiency.