The soybean F-box protein GmFBX176 regulates ABA-mediated responses to drought and salt stress.

• GmFBX176 encodes a nuclear-localized F-box protein that responds to PEG treatment, ABA treatment, and salt stress at the transcriptional level. • Stress tolerance analysis of heterologous GmFBX176-overexpressing Arabidopsis revealed that GmFBX176 is a negative regulatory protein that improves tolerance to drought and salt stress. • GmFBX176-overexpressing Arabidopsis displayed reduced sensitivity to ABA. • Constitutive heterologous overexpression of the GmFBX176 gene affects stress-related physiological indicators and the transcript levels of stress response genes in transgenic Arabidopsis. As key components of the E3 ubiquitin ligase in the Skp1/Cullin or CDC53/F-box (SCF) complex, F-box proteins are involved in plant abiotic stress responses. However, the functions of F-box proteins in soybean in response to abiotic stress remain unclear. In this study, the soybean F-box protein-encoding gene GmFBX176 was cloned and functionally analyzed. GmFBX176 localized to the nucleus, was widely expressed in tissues (with the highest level in the roots), and responded to polyethylene glycol (PEG) treatment, abscisic acid (ABA) treatment, and salt stress at the transcriptional level. GmFBX176 -overexpressing Arabidopsis had lower survival rates; faster water loss rates; lower proline, sucrose and chlorophyll contents; greater malondialdehyde (MDA) contents; greater relative electrical conductivity (REC); and greater drought stress sensitivity than did wild-type (WT) Arabidopsis. Moreover, GmFBX176 -overexpressing Arabidopsis had lower survival rates, lower chlorophyll content, lower superoxide dismutase (SOD) activity, greater sensitivity to salt stress, longer roots, greater stomatal opening rates, and lower sensitivity to ABA than did WT Arabidopsis. Transcriptome sequencing and quantitative real-time PCR (qPCR) analyses revealed that GmFBX176 affects the transcript levels of stress response genes. These results indicate that GmFBX176 regulates ABA-mediated responses to drought and salt stress. [ABSTRACT FROM AUTHOR]