DELAYED HEADING DATE3, Encoding a Heat Shock Transcription Factor, Delays Flowering Time and Improves Yield in Rice (Oryza sativa L.)

Heading date is an essential agronomic trait that affects adaptability and yield in rice (Oryza sativa). HSFs (heat shock transcription factors) are a type of transcription factor that responds to environmental stress in organisms. The relationship between the heading date and HSFs has been seldom reported so far. Here, we identified a new heat shock transcription factor, named DELAYED HEADING DATE3 (DHD3), which can significantly delay the heading date by about 14 days and provide improvements of about 77% potential yield in rice. DHD3 protein is localized in the nucleus and has weak transactivation activity. DHD3 delays the heading date by significantly suppressing Hd3a and RFT1 expression under long-day (LD) and short-day (SD) conditions. Furthermore, the low-temperature condition greatly enhances the delay effect of DHD3 on the heading date (from 16.1% to more than 89.3%). We propose that DHD3 may involve the temperature-regulated signaling pathway of flowering time in rice and has the potential to improve crop yield.