A positive feedback loop formed between OsFTIP9 and OSH1 orchestrates temperature-sensitive seed germination in rice

Area of Science:

• Plant Biology
• Molecular Biology
• Genetics

Background:

• Seed germination is vital for plant establishment but is sensitive to environmental factors like temperature.
• The molecular basis of temperature-sensitive seed germination, particularly in rice, is not fully understood.

Purpose of the Study:

• To identify and characterize the molecular mechanisms controlling temperature-sensitive seed germination in rice.
• To elucidate the role of the OsFTIP9-OSH1 regulatory module in this process.

Main Methods:

• Genetic analysis of rice mutants (osftip9 and OSH1 RNAi).
• Molecular assays to study protein-protein interactions and gene expression.
• Analysis of nuclear translocation and ABA biosynthesis pathways.

Main Results:

• OsFTIP9 sequesters OSH1 in the cytosol, promoting germination at optimal temperatures.
• Nuclear OSH1 activates ABA biosynthesis genes (OsNCED3, OsNCED5) and facilitates chromatin looping.
• Low temperatures disrupt OsFTIP9-OSH1 interaction, leading to OSH1 nuclear accumulation, increased ABA, and dormancy.
• A positive feedback loop exists where reduced nuclear OSH1 upregulates OsFTIP9.

Conclusions:

• The OsFTIP9-OSH1 module functions as a temperature-sensitive switch regulating rice seed germination.
• This module integrates environmental cues to control ABA biosynthesis and dormancy via spatial protein sequestration and reciprocal regulation.
• Findings offer insights into improving cold tolerance during rice germination.