The Heat Shock Transcription Factor OsHsfA2a Modulates Rice Seed Dormancy and Pre-Harvest Sprouting With OsSD6.

OsHsfA2a is a negative regulator of rice seed dormancy, and hsfa2a knockout mutants show enhanced pre-harvest sprouting resistance without reducing yield potential or post-harvest germination rates.

• Why it matters: The dormancy–PHS trade-off limits crop improvement because too little dormancy causes sprouting, while too much dormancy harms germination uniformity.
• What they did: The study combined genetic analysis (including sd6 hsfa2a double mutants) with mechanistic assays showing OsHsfA2a self-association and activation of the ABA catabolic gene OsABA8ox3, plus biochemical interaction between OsSD6 and OsHsfA2a.
• The result: OsSD6 is epistatic to OsHsfA2a and transcriptionally activates OsHsfA2a, while accumulating OsSD6 protein competitively attenuates OsHsfA2a DNA-binding, supporting a multi-tier regulatory module for ABA catabolism and dormancy control.

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