Identification and characterization of fast-neutron induced mutants with elevated seed protein content in soybean

Authors: PRENGER, ELIZABETH - University Of Georgia; OSTEZAN, ALEXANDRA - University Of Georgia; Mian, Rouf; STUPAR, ROBERT - University Of Minnesota; GLEN, TRAVIS - University Of Georgia; LI, ZEHGLU - University Of Georgia

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/11/2019
Publication Date: 7/24/2019
Citation: Prenger, E.M., Ostezan, A., Mian, R.M., Stupar, R.M., Glen, T., Li, Z. 2019. Identification and characterization of fast-neutron induced mutants with elevated seed protein content in soybean. Theoretical and Applied Genetics. https://doi.org/10.1007/s00122-019-03399-w.
DOI: https://doi.org/10.1007/s00122-019-03399-w

Interpretive Summary: Seed protein and oil contents are the two most important components of soybean, and improving these traits are often a major goal for soybean breeders. Fast neutron radiation, a technique, that may induce genomic mutations resulting in novel variation for traits of interest. Two elite soybean lines were irradiated with fast neutrons and screened for altered seed composition. Twenty-three lines with altered protein, oil, or sucrose content were selected based on near-infrared (NIR) spectroscopy data from five environments and yield tested at five locations. Mutants with significantly increased protein averaged 14 to 29 g kg-1 more protein than the parents. Comparative genomic hybridization (CGH) identified putative mutations in a mutant, G15FN-12, that has 24 g kg-1 higher protein than the parent genotype, and whole genome sequencing (WGS) of the mutant has confirmed these mutations. An F2:3 population was developed from G15FN-12 to determine association between genomic changes and increased protein contents. Bulked segregant analysis of the population using the SoySNP50K BeadChip identified a CGH- and WGS-confirmed deletion on chromosome 12 responsible for elevated protein content. The population was genotyped using a KASP marker designed at the mutation region. Significant association (P<0.0001) between the deletion on chromosome 12 and elevated protein content was observed and confirmed in the F3:4 generation. The F2 segregants homozygous for the deletion averaged 27 g kg-1 higher seed protein and 8 g kg-1 lower oil than homozygous wild type segregants. These high protein mutants are new high yielding elite sources for development of varieties with improved seed protein contents.

Technical Abstract: Soybean seed composition affects the utility of soybean, and improving seed composition is an essential goal for soybean breeders. Fast neutron radiation introduces genomic mutations resulting in novel variation for traits of interest. Two elite soybean lines were irradiated with fast neutrons and screened for altered seed composition. Twenty-three lines with altered protein, oil, or sucrose content were selected based on near-infrared (NIR) spectroscopy data from five environments and yield tested at five locations. Mutants with significantly increased protein averaged 14 to 29 g kg-1 more protein than the parents. Comparative genomic hybridization (CGH) identified putative mutations in a mutant, G15FN-12, that has 24 g kg-1 higher protein than the parent genotype, and whole genome sequencing (WGS) of the mutant has confirmed these mutations. An F2:3 population was developed from G15FN-12 to determine association between genomic changes and increased protein content. Bulked segregant analysis of the population using the SoySNP50K BeadChip identified a CGH- and WGS-confirmed deletion on chromosome 12 responsible for elevated protein content. The population was genotyped using a KASP marker designed at the mutation region. Significant association (P<.0001) between the deletion on chromosome 12 and elevated protein content was observed and confirmed in the F3:4 generation. The F2 segregants homozygous for the deletion averaged 27 g kg-1 higher seed protein and 8 g kg-1 lower oil than homozygous wild type segregants. Mutants with altered seed composition are a new resource for gene function studies and provide elite materials for the development of varieties with improved seed composition.