Cytokinin histidine kinase receptors regulate multiple aspects of rice growth and development.
Shouse EM, Aragón-Raygoza A, Tallerday EJ, Healy T, Zhou W
Crispr
Grasses from your backyard lawn to ornamental bamboo share the same hormonal wiring this study just mapped in rice — so precision edits to cytokinin receptors now give breeders exact levers to reshape how any grass branches, tillers, or sets seed.
Cytokinin is a plant hormone that works like a control tower, telling a plant when to sprout, how to branch, and how many seeds to make. Researchers used gene editing to disable the four 'antennas' rice uses to receive cytokinin signals — and found that plants missing all four couldn't even grow their first shoot, essentially stopping at birth. The ones missing only one or two antennas survived but showed striking differences: some made fewer side branches on their grain heads, others made fewer seeds, revealing that each antenna handles a distinct job.
Key Findings
Rice plants with all four cytokinin receptors disabled were completely shootless — they failed to develop a shoot apical meristem and could not grow above ground at all.
The four receptors specialize: HK4 promotes seed fertility, HK3 and HK5 drive secondary branch formation in the grain head, and HK6 drives primary branch formation — each receptor controls a distinct architectural outcome.
All cytokinin-regulated gene activity in rice flows exclusively through these four receptors, even though rice carries an additional cytokinin-binding protein, suggesting no alternate signaling pathway compensates.
chevron_right Technical Summary
Scientists used CRISPR to knock out all four cytokinin receptor proteins in rice, revealing that this single hormone governs everything from the plant's very first shoot to how many grain-bearing branches it produces — and that rice depends on cytokinin far more fundamentally than the model plant Arabidopsis does.
Abstract Preview
The phytohormone cytokinin has diverse functions in plants, most of which have been primarily elucidated in the eudicotyledonous plant Arabidopsis (Arabidopsis thaliana). To further characterize th...
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