Seed inoculation with Rhizobium japonium bacteria improved fatty acid composition of different soybean (Glycine max L.) genotypes

Background

Soybean is an important crop for food security as it fulfills global oil requirements. Seed inoculation with bacteria is frequently used to increase its production; however, it could change the seed composition. Nevertheless, the genotypes respond differently to the bacteria. Therefore, it is necessary to assess the impact of Rhizobium bacteria on the seed composition.

Methods

This two-year (2018 and 2019) study investigated the effects of seed inoculation with Rhizobium japonicum on fatty acid composition of different soybean genotypes. Three frequently cultivated soybean genotypes, i.e., ‘Gapsoy16′, ‘Traksoy’, and ‘İlksoy’ were included in the study. The seeds were either inoculated with R. japonicum or sown without inoculation. The fatty acid profile, i.e., saturated fatty acids (palmitic and stearic acid) and unsaturated fatty acids (oleic, linoleic, linolenic, and arachidic acids) was determined, and the collected data were analyzed by single and multivariate analysis.

Results

Seed inoculation with R. japonicum significantly altered the fatty acid composition of different genotypes; however, varied effects were recorded for the genotype. Linoleic acid, oleic acid, and palmitic acid made up ∼ 33 % of total fatty acids in seeds. Linoleic acid contents varied between 30.78–34.02 %, whereas oleic acid contents ranged between 27.85–31.04 %. Similarly, palmitic acid contents differed between 15.53–16.93 %. The ‘İlksoy’ and ‘Gapsoy’ had the highest contents of palmitic and oleic acids, respectively. Overall, inoculation of bacteria increased the composition of unsaturated fatty acids and lowered saturated fatty acids.

Conclusion

Seed inoculation with R. japonicum increased the essential fatty acid composition in ‘Traksoy’ genotype. However, ‘İlksoy’ genotype recorded a decrease in unsaturated fatty acids. Therefore, ‘Traksoy’ can be inoculated with R. japonicum to improve fatty acid profile.