Extensin-Like Protein OsPEX1 Affects Seed Germination by Modulating Water Permeability of Seed Coat in Rice

Area of Science:

• Plant Biology
• Molecular Biology
• Seed Physiology

Background:

• Seed coat lipid barriers, cutin and suberin, regulate water permeability crucial for germination.
• Molecular mechanisms governing seed coat permeability are not fully understood.

Purpose of the Study:

• To investigate the role of rice EXTENSIN-like protein OsPEX1 in modulating seed coat water permeability and its impact on germination.

Main Methods:

• Comparative analysis of wild-type and gain-of-function pex1/pex1 rice mutants.
• Morphological observation of embryo growth.
• Assessment of water absorption in the seed coat.
• Integrated transcriptional and metabolic analyses.

Main Results:

• The pex1/pex1 mutant exhibited lower germination rates and inhibited embryo growth compared to wild-type.
• Impaired water absorption was observed in the pex1/pex1 mutant seed coat, particularly around the micropyle.
• Overexpression of the transcriptional repressor OsClo5 in the mutant correlated with increased cutin and suberin deposition.

Conclusions:

• OsPEX1 plays a critical role in regulating water absorption in the rice seed coat.
• Abnormal cutin and suberin deposition, potentially mediated by OsClo5, contributes to reduced water permeability in pex1/pex1 seeds.
• OsPEX1 influences seed germination by modulating seed coat permeability.