The MKKK62-MKK3-MAPK7/14 module negatively regulates seed dormancy in rice

Area of Science:

• Plant Biology
• Molecular Genetics
• Signal Transduction

Background:

• Seed dormancy is crucial for rice quality and yield, but its regulatory mechanisms remain complex.
• The Mitogen-Activated Protein Kinase (MAPK) cascade is implicated in various signaling pathways, with MKK3 recently linked to seed dormancy.
• The precise role and mechanism of MKK3 in seed dormancy regulation are yet to be fully elucidated.

Purpose of the Study:

• To investigate the function of MKKK62 in rice seed dormancy.
• To elucidate the molecular pathway, including the MAPK cascade, involved in regulating seed dormancy.
• To understand how MKKK62 influences abscisic acid (ABA) sensitivity and OsMFT transcription.

Main Methods:

• Generation of MKKK62-overexpressing (OE) rice lines.
• Analysis of seed dormancy, ABA sensitivity, and OsMFT transcript levels in OE and knockout lines.
• Yeast two-hybrid assays to identify protein-protein interactions within the MAPK cascade.
• Knock-out experiments to confirm gene functions (MKK3, MAPK7, MAPK14).

Main Results:

• MKKK62 overexpression led to a loss of seed dormancy and decreased ABA sensitivity.
• MKKK62 interacts with MKK3, which in turn interacts with MAPK7 and MAPK14.
• Knockout of MKK3, MAPK7, or MAPK14 confirmed their involvement in seed dormancy regulation.
• MKKK62 negatively regulates OsMFT transcription, a key gene in seed dormancy.

Conclusions:

• MKKK62 acts as a negative regulator of rice seed dormancy.
• The MKKK62-MKK3-MAPK7/MAPK14 cascade controls seed dormancy by modulating ABA sensitivity and OsMFT transcription.
• Phosphorylation events mediated by this MAPK cascade are critical for controlling seed dormancy in rice.