The analysis of the genetic loci affecting phenotypic plasticity of soybean isoflavone content by dQTG.seq model.

Key message: The dQTG.seq model was utilized to investigate the genetic underpinnings of phenotypic plasticity in soybean isoflavone content, leading to the identification of 100 marker sites associated with phenotypic plasticity, including 27 transcription factors. Overexpression of Glyma.18G091600 (GmERF7) hairy roots under low temperature, salt, and drought stress confirmed the regulatory role of GmERF7 in the phenotypic plasticity of soybean isoflavone content. Phenotypic plasticity is characteristic of organisms that undergo phenotypic changes in response to environmental fluctuations. This phenomenon is pivotal in evolutionary processes and the emergence of new traits. Isoflavones, significant secondary metabolites found in soybeans, have garnered considerable attention owing to their beneficial physiological effects on human health. The variation in isoflavone content among different soybean varieties is influenced by diverse environmental factors, thereby influencing the evaluation of high and low isoflavone varieties. In this study, we measured the phenotypic plasticity of isoflavone content in recombinant inbred lines Hefeng 25 and L-28 in three different environments over two years. Utilizing the dQTG.seq model, 100 statistically significant markers were identified, and 101 potential genes, including 27 transcription factors, were screened. Through qRT-PCR analysis, elevated expression levels of Glyma.18G091600, Glyma.09G196200, and Glyma.05G229500 were observed in various parts of soybean plants. Under low temperature, drought or salt stress conditions, the related enzymes involved in the isoflavone synthesis pathway were notably upregulated in Glyma.18G091600 (GmERF7) overexpressed hairy roots compared to wild-type controls, resulting to higher phenotypic plasticity values for DZ, GC, GT, and TI. These results suggest that GmERF7 influences the phenotypic plasticity of soybean isoflavone content, enhancing adaptation to adverse environments, while also promoting the synthesis and accumulation of soybean isoflavones.