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TTG1 complex MYBs, MYB5 and TT2, control outer seed coat differentiation
Antonio Gonzalez1, John Mendenhall, Yujia Huo
1Section of Molecular Cell and Developmental Biology and The Institute for Cellular and Molecular Biology, The University of Texas at Austin, 2500 Speedway, Austin, TX 78712, USA. tga@mail.utexas.edu
Developmental Biology
|November 11, 2008
Summary
Researchers identified two MYB proteins, AtMYB5 and TT2, crucial for Arabidopsis outer seed coat development. MYB5 plays a major role, with both proteins showing partial redundancy and novel developmental pleiotropy.
Area of Science:
- Plant Molecular Biology
- Developmental Genetics
- Arabidopsis thaliana research
Background:
- Epidermal cell fate in Arabidopsis is regulated by a combinatorial complex of WD repeat, bHLH, and MYB proteins.
- Previous studies identified components for trichome initiation, root hair spacing, and anthocyanin production, but MYB members for outer seed coat differentiation remained unknown.
Purpose of the Study:
- To identify the elusive MYB protein(s) involved in the WD-bHLH-MYB complex-dependent regulation of outer seed coat development in Arabidopsis.
- To investigate the roles and potential pleiotropy of identified MYB proteins in seed coat and other epidermal development.
Main Methods:
- Genetic analysis of MYB mutants in Arabidopsis.
- Expression analysis of MYB genes in seed coat tissues.
- Analysis of downstream regulatory gene expression in MYB mutants.
Main Results:
- AtMYB5 and TT2 were identified as partially redundant MYB proteins regulating outer seed coat development, with AtMYB5 being the primary regulator.
- Both MYB5 and TT2 are expressed in the outer seed coat domain.
- AtMYB5 exhibits weak pleiotropic effects on trichome development and tannin production.
- Downstream regulators TT8, GL2, and TTG2 were downregulated in the identified MYB mutants.
Conclusions:
- The study elucidates the roles of AtMYB5 and TT2 in outer seed coat development, filling a gap in understanding the WD-bHLH-MYB complex.
- The findings reveal novel, previously undetected developmental pleiotropy among TTG1-dependent R2R3 MYB proteins, challenging assumptions of high pathway specificity.
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