ZmbZIP39 coordinates source-flow-sink relations to boost grain filling in maize

Area of Science:

• Plant Biology
• Molecular Genetics
• Agricultural Science

Background:

• Efficient grain filling in maize relies on coordinated source, flow, and sink processes.
• The regulatory network governing these processes is not fully understood.
• Sucrose transporter ZmSUT1 is crucial for phloem loading and unloading.

Purpose of the Study:

• To identify key regulators of maize grain filling.
• To elucidate the role of ZmbZIP39 in coordinating source-flow-sink relationships.

Main Methods:

• Utilized ZmSUT1 as a molecular target to identify regulators.
• Investigated the transcriptional regulation of photosynthesis, sucrose transport, and metabolism genes.
• Analyzed the interaction of ZmbZIP39 with other regulatory factors.

Main Results:

• Identified ZmbZIP39 as a central coordinator of grain filling.
• ZmbZIP39 directly activates ZmSUT1 and ZmSUT7 for sucrose transport.
• ZmbZIP39 upregulates sucrose synthase genes and zein-encoding genes for nutrient storage.
• ZmbZIP39 forms a regulatory complex and exhibits autoactivation, creating a positive feedback loop.

Conclusions:

• ZmbZIP39 is a pivotal transcription factor regulating source-flow-sink dynamics in maize.
• Understanding ZmbZIP39's role provides insights into improving crop yield and nutrient content.