AtMYB61, an R2R3-MYB transcription factor, functions as a pleiotropic regulator via a small gene network

• Published in: The New phytologist Vol. 195; no. 4; pp. 774 - 786
• Main Authors: Romano, Julia M., Dubos, Christian, Prouse, Michael B., Wilkins, Olivia, Hong, Henry, Poole, Mervin, Kang, Kyu‐Young, Li, Eryang, Douglas, Carl J., Western, Tamara L., Mansfield, Shawn D., Campbell, Malcolm M.
• Format: Journal Article
• Language: English
• Published: Oxford, UK New Phytologist Trust 01-09-2012; Blackwell Publishing Ltd; Wiley Subscription Services, Inc; Wiley
• Subjects: Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - ultrastructure; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Base Sequence; Biology; cell wall; Cell Wall - metabolism; Cell walls; Cotyledon - growth & development; Cotyledon - metabolism; Cytology; Fiber cells; Function analysis; Gene expression; Gene Expression Regulation, Plant; Gene Regulatory Networks - genetics; Genes; Genetic Pleiotropy; Genetics; Genotypes; Hypocotyls; Life cycle; Life cycles; Life Sciences; Molecular Sequence Data; MYB; Nucleotide Motifs - genetics; Phenotype; Phenotypes; Plant growth; Plant roots; Plant Roots - growth & development; Plant Roots - metabolism; Plant Stems - growth & development; Plant Stems - metabolism; Plant Stems - ultrastructure; Plants; Promoter Regions, Genetic - genetics; Protein Transport - genetics; Regulatory sequences; Resource allocation; root architecture; seed coat mucilage; Seedlings; Seeds; Transcription; Transcription Factors - genetics; Transcription Factors - metabolism; Transcriptomes; transpiration stream; Xylem; Xylem - metabolism; xylem; root architecture; ARABIDOPSIS-THALIANA; MYB PROTEINS; CARBON; seed coat mucilage; PLANT DEVELOPMENT; SINK REGULATION; transpiration stream; ECTOPIC LIGNIFICATION; SEED COAT; MYB; GROWTH; WALL BIOSYNTHESIS; cell wall; LIGNIN BIOSYNTHESIS
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/j.1469-8137.2012.04201.x

Throughout their lifetimes, plants must coordinate the regulation of various facets of growth and development. Previous evidence has suggested that the Arabidopsis thaliana R2R3-MYB, AtMYB61, might function as a coordinate regulator of multiple aspects of plant resource allocation.
Using a combination of cell biology, transcriptome analysis and biochemistry, in conjunction with gain-of-function and loss-of-function genetics, the role of AtMYB61 in conditioning resource allocation throughout the plant life cycle was explored.
In keeping with its role as a regulator of resource allocation, AtMYB61 is expressed in sink tissues, notably xylem, roots and developing seeds. Loss of AtMYB61 function decreases xylem formation, induces qualitative changes in xylem cell structure and decreases lateral root formation; in contrast, gain of AtMYB61 function has the opposite effect on these traits. AtMYB61 coordinates a small network of downstream target genes, which contain a motif in their upstream regulatory regions that is bound by AtMYB61, and AtMYB61 activates transcription from this same motif. Loss-of-function analysis supports the hypothesis that AtMYB61 targets play roles in shaping subsets of AtMYB61-related phenotypes.
Taken together, these findings suggest that AtMYB61 links the transcriptional control of multiple aspects of plant resource allocation.