Promoter deletion in the soybean Compact mutant leads to overexpression of a gene with homology to the C20- gibberellin 2-oxidase family

Authors: LIU, XING - University Of Illinois; WICKLAND, DANIEL - University Of Illinois; LIN, ZHICONG - University Of Illinois; LIU, QUILIN - Fujian Agricultural & Forestry University; BORGES DOS SANTOS, LUCAS - University Of Illinois; Hudson, Karen; HUDSON, MATTHEW - University Of Illinois

Submitted to: Journal of Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/16/2023
Publication Date: 8/8/2023
Citation: Liu, X., Wickland, D., Lin, Z., Liu, Q., Borges Dos Santos, L., Hudson, K.A., Hudson, M.E. 2023. Promoter deletion in the soybean Compact mutant leads to overexpression of a gene with homology to the C20- gibberellin 2-oxidase family. Journal of Experimental Botany. https://doi.org/10.1093/jxb/erad267.
DOI: https://doi.org/10.1093/jxb/erad267

Interpretive Summary: Although much is known about the plant hormones that regulate plant growth and height, a limited number of genetic variants for this trait are available in soybean. We determined that a newly isolated dwarf soybean mutant carried a mutation that caused it to express too much of a gene that regulates gibberellic acid, a plant hormone that is known to affect cell elongation and plant height. The identification of this mutant allowed the development of new approaches for mapping architectural traits in soybeans, and provides new characterized soybean genetic variation that could be used to breed semi-dwarf soybean varieties.

Technical Abstract: Control of stem elongation and plant architecture remains an untapped tool to optimize plant productivity, and the understanding of the genetic and hormonal control of growth in important crops offers promise for future modifications that can improve yield and other agronomic traits. Here we report the characterization of the Compact mutant from a population of the soybean cultivar Williams-82. The mutant has a dominant phenotype of a compact growth habit with reduced stem elongation throughout the vegetative stage. The candidate gene was mapped to a genetic interval on soybean linkage group D2 (chromosome 17) spanning 12.2 megabases. Fine mapping localized the causative mutation to a region containing only two genes. A deletion in the promoter region of one of these genes was identified after whole-genome resequencing. The deletion in the promoter of Glyma.17g145200, encoding a member of the GA 2-oxidase family involved in metabolism of gibberellic acid, resulted in the increased expression of the GA 2-oxidase transcript in vegetative stages. Levels of inactive GAs were altered in the Compact mutant with respect to wild type seedlings, and the mutant phenotype can be rescued with exogenous GA3, supporting a role for this gene in gibberellic acid metabolism. Transgenic overexpression of Glyma.17G145200 in Arabidopsis results in dwarfed plants demonstrating a conserved function for this gene in hormone metabolism across species. This novel gain-of-function mutant demonstrates a role for GA2-oxidase in soybean architecture.