Development and phenotypic screening of an ethyl methane sulfonate mutant population in soybean

Authors: ESPINA, MARY - Tennessee State University; AHMED, SABBIR C - Tennessee State University; BERNARDINI, ANGELINA - Tennessee State University; ADELEKE, DAYO - Tennessee State University; YADEGARI, ZEINAB - Tennessee State University; PANTALONE, VINCENT - University Of Tennessee; Arelli, Prakash; TAHERI, ALI - Tennessee State University

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2018
Publication Date: 3/29/2018
Citation: Espina, M.J., Ahmed, S.M., Bernardini, A., Adeleke, D., Yadegari, Z., Pantalone, V.R., Arelli, P.R., Taheri, A. 2018. Development and phenotypic screening of an ethyl methane sulfonate mutant population in soybean. Frontiers in Plant Science. 9:394. https://doi.org/10.3389/fpls.2018.00394.
DOI: https://doi.org/10.3389/fpls.2018.00394

Interpretive Summary: Worldwide, soybean grown for its edible protein and oil, is a very important agronomic crop. Soybean yields must be improved for sustainable production. Genetic improvement of the crop is most important to meet the increasing demands for soybean consumption. Primarily, genetic improvement is achieved through breeding methods provided, genetic variability exists in naturally available soybean sources. Additionally, breeding process is slow and time consuming. Other methods should be adopted to accelerate the process such as mutation breeding using chemicals and radiations. An agent which causes changes in the plant genetic structure is known as mutagenic agent. A conventional soybean line JTN-5203, developed and released by USDA-ARS, Jackson, TN for high yields, resistance to multiple fungal pathogens and nematodes was used to produce variations. Ethyl methane sulfonate (EMS) is a known chemical mutagenic agent that was used to treat seeds of soybean JTN-5203 for inducing genetic variability. Standard methods were applied to treat the seeds of JTN-5203 with different concentrations of EMS. A total of 1820 individual first generation of plants called M1 plants were recovered from 15,000 treated seeds. The M1 seeds that were produced by M1 plants were individually planted in the field to produce second generation (M2) plants. DNA samples were extracted from 6400 individual M2 plants using standard techniques. The M2 plants in the field were scored for phenotypic variations (appearance). Individually, M2 plants were harvested for seed and analyzed for seed composition. Seed composition included, total oil content, protein, starch, moisture content, fatty acid and amino acid compositions. Compared to check JTN-5203, variants called mutants produced from EMS treatments resulted in higher percentage of protein (50%) and oil content (25%). In general most soybeans have linolenic acid in the range of 5-7%, but lower concentrations are most desirable for healthy consumption. A few mutants with 2-3% linolenic acid were recovered. The progenies of individual mutant plants will be further studied for stability of these traits. Soybeans with lower than 5-7% of linolenic acid will bring premium price to soybean growers and are most desirable for healthy consumption. Ultimately, Americans will be the beneficiaries.

Technical Abstract: Soybean is an important oil-producing crop in the Fabaceae family and is utilized in various industries. With increasing demands for soybean oil and other soybean products, its production must be increased. Genetic improvement of the crop is important to meet the increasing demands for soybean. A new soybean mutant population was generated through induced ethyl methane sulfonate (EMS) mutagenesis using the newly released germplasm, JTN-5203 (maturity group V). Initially, EMS concentration were optimized to get the suitable concentration. Seeds were treated with different concentrations of EMS varying from 0 to 150 mM. The optimum concentration determined was used to treat bulk JTN-5203 seeds. A total of 1,820 individuals of the M1 population were produced from 15,000 treated seeds. The M2 population were planted in the field and DNA were extracted from 6,400 individual plants. Phenotypic variations were recorded in the M2 generation including changes in leaf morphology, plant architecture, seed compositions and final plant yield. Total oil, protein, starch, moisture content, and fatty acid and amino acid compositions were among the seed traits that were measured in the mutants. Compared to wild-type, we recovered mutants with average protein (41%) and oil content (21.2%), we recovered mutants with higher protein and oil contents of 50% and 25% respectively. Oleic acid content in some of the mutants was also increased up to 40% where in wild type it was 25%. Linoleic acid in five mutants was reduced to 35% while in wild type it was 49%. Linolenic acid in wild type was about 7.6% and we recovered mutants with reduced linolenic acids at 2.9%. The EMS mutant population will be used for further studies including screening for various traits such as amino acid pathways, allergens, phytic acids and other important soybean agronomic traits. Beneficial traits from these mutants can be exploited for future soybean breeding programs. This germplasm can also be used for discovering novel mutant alleles and for functional gene expression analysis using reverse genetics tools such as TILLING.