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ARS Home » Pacific West Area » Pullman, Washington » Grain Legume Genetics Physiology Research » Research » Publications at this Location » Publication #407680
Research Project: Enhanced Agronomic Performance and Disease Resistance in Edible Legumes

Location: Grain Legume Genetics Physiology Research

Title: T and Z, two partial seed coat color patterning genes in common bean, provide insight into the structure and protein interactions of a MBW complex in plants

Author
item MCCLEAN, PHIL - North Dakota State University
item ROY, JAYANTA - North Dakota State University
item COLBERT, CHRISTOPHER - North Dakota State University
item OSBORNE, CAROLINE - North Dakota State University
item LEE, RIAN - North Dakota State University
item Miklas, Phillip - Phil
item OSORNO, JUAN - North Dakota State University

Submitted to: Journal of Experimental Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/30/2024
Publication Date: 8/21/2024
Citation: Mcclean, P., Roy, J., Colbert, C., Osborne, C., Lee, R., Miklas, P.N., Osorno, J. 2024. T and Z, two partial seed coat color patterning genes in common bean, provide insight into the structure and protein interactions of a MBW complex in plants. Journal of Experimental Biology. https://doi.org/10.1093/g3journal/jkae184.
DOI: https://doi.org/10.1093/g3journal/jkae184

Interpretive Summary: The seed coat color of dry beans influences market type and flavonoid content and composition. There are numerous genes which influence seed coat color and patterning (striped, mottling, etc.). We investigated the role of T and Z genes in regulating color distribution in seeds. The candidate genes and proteins they encode for were identified. T encodes a propeller WDR protein and Z encodes a MYB protein. These proteins interact to form an MBW protein complex which regulates expression of genes in the flavonoid pathway with subsequent effects on color deposition in the seed coats. DNA markers were developed to track the genes. These new tools and the knowledge gained for T and Z genes will aid breeders in selection of dry bean market types with specific seed coat colors and patterns and provide scientists with a better understanding of protein interactions influencing the flavonoid pathway.

Technical Abstract: Flavonoids are important secondary metabolites associated with coloring seeds and flowers. A ternary MBW protein complex consisting of interfacing MYB, beta-helix-loop-helix (bHLH), and WD40 repeat (WDR) proteins controls the expression of late biosynthetic genes in the flavonoid pathway. The common bean (Phaseolus vulgaris L.) bHLH component was previously cloned and was determined to be the P gene, the master regulator of flavonoid expression. Two other genes, T and Z, are also historically considered regulators, since they do not regulate color expression per se, but rather determine the distribution of color in seeds and flowers. These two genes were cloned using reverse genetics based on genetic mapping, candidate gene selection, and mutational analysis of several natural variants. Domain and AlphaFold2 (AF2) analyses determined T encoded a seven-bladed ß-propeller WDR protein, while Z encoded a R2R3 MYB protein. Modeling of recessive T and Z mutant alleles determined they encoded proteins with altered structures. Modeling of the Z MYB/P bHLH/T WDR MBW complex identified interfacing sequence domains and motifs in all three genes that are conserved in dicots. One Z MYB motif is a possible ß-MoRF that only appears in a structured state when Z MYB is modeled in a MBW complex. Complexes containing mutant T and Z proteins changing the interaction of members of the complex ways that would alter their role in regulating expression of genes in the flavonoid pathway.