Zinc Finger Transcriptional Repressor ZOS5-09 Regulates Grain Filling and Development in Rice.

Area of Science:

• Plant Molecular Biology
• Agricultural Science
• Genetics

Background:

• Grain size is a critical factor influencing rice yield.
• Transcription factors play vital roles in regulating plant development and grain traits.
• Understanding the genetic mechanisms controlling grain size is essential for improving crop productivity.

Purpose of the Study:

• To investigate the function of the C2H2 zinc finger transcription factor ZOS5-09 in rice grain development.
• To elucidate the regulatory role of ZOS5-09 in controlling grain size, cell proliferation, and quality.
• To explore the molecular mechanisms underlying ZOS5-09's function as a transcriptional repressor.

Main Methods:

• Analysis of ZOS5-09 expression patterns using a promoter::GUS construct.
• In planta reporter effector assays and subcellular localization studies.
• Generation and analysis of transgenic rice plants with altered ZOS5-09 expression (overexpression, knock-down, CRISPR knock-out).
• Molecular analyses including gene expression profiling and ChIP assays.

Main Results:

• ZOS5-09 is a nuclear-localized transcriptional repressor with a nucleolar retention signal (NoRS).
• Altered ZOS5-09 expression (lethality upon overexpression, detrimental effects without NoRS) highlights the importance of optimal levels.
• Knock-down or knock-out of ZOS5-09 reduced grain length/weight but increased width, linked to altered cell proliferation and expansin expression.
• ZOS5-09 represses GLU6 gene expression via interaction with histone deacetylase, affecting starch and protein content and increasing chalkiness.

Conclusions:

• Optimal expression of ZOS5-09 is essential for normal rice grain development and quality.
• ZOS5-09 acts as a transcriptional repressor, influencing grain size through regulation of cell cycle and storage protein genes.
• This study enhances understanding of transcriptional regulatory networks governing rice grain traits.