OsIAA23 Promotes Heading by Directly Downregulating Ghd7 in rice

Area of Science:

• Plant Molecular Biology
• Crop Science
• Genetics

Background:

• Ghd7 is a key regulator of rice growth and development.
• The upstream regulatory mechanisms of Ghd7 are not fully understood.

Purpose of the Study:

• To identify the upstream regulator of Ghd7.
• To elucidate the regulatory mechanism of Ghd7 in rice flowering time.

Main Methods:

• Screening of truncated Ghd7 promoter fragments using electrophoretic mobility shift assays.
• Yeast one-hybrid screening to identify transcription factors binding to Ghd7 promoter.
• Dual-luciferase transient assays to confirm OsIAA23's regulatory effect.
• Genetic analysis of wild-type and mutant rice lines.

Main Results:

• OsIAA23 was identified as a direct upstream regulator of Ghd7.
• OsIAA23 transcriptionally represses Ghd7 expression, with binding sites located 1264-1255 bp upstream of ATG.
• OsIAA23 downregulation of Ghd7 leads to delayed heading under long-day conditions.
• Natural variations in the Ghd7 promoter region are linked to heading and geographic distribution.

Conclusions:

• OsIAA23 directly regulates Ghd7 expression, impacting rice flowering time.
• This finding expands our understanding of the Ghd7-mediated flowering regulatory network in rice.
• Natural variations in Ghd7 regulatory regions contribute to rice adaptation and diversity.