*4.8. Determination of Antioxidant Enzyme Activities and ROS Contents*

To determine the antioxidant enzyme activities and ROS contents, the yeast cells were harvested 14 h after the NaCl treatment at 28 ◦C and stored at −80 ◦C. The antioxidant enzyme activities and ROS and MDA contents were analyzed using the service provided by Nanjing Ruiyuan Biotechnology company (https://bestofbest.top/).

#### **5. Statistical Analysis**

Three independent biological replications were used for each treatment, and the whole experiment was repeated three times. The data were statistically analyzed using an analysis of variance, and compared with the control using the LSD test (*p* > 0.05) by using the Statistix 8.1 software (https://www.statistix.com/). The Graphpad Prism 5 software was used for graphical presentation.

#### **6. Conclusions**

In this study, four S1fa family proteins were identified in Chinese cabbage, and the chromosomal location, structure, phylogenetic tree and physiochemical properties were analyzed, and molecular characterization performed in yeast, to understand their involvement in abiotic stress tolerance. The S1fa proteins have three highly conserved motifs. Moreover, the cis-elements and miRNAs targeting S1fa genes were predicted to understand the regulatory mechanism. The expression patterns of the S1fa gene in different tissues and their responses to abiotic stresses show that these genes may play a significant role in the growth and development of Chinese cabbage. In yeast, *Bra034084* and *Bra029784* was highly sensitive to salt stresses and might activate the expression of cell wall biosynthesis genes. For the first time, we elucidate the functions of the S1fa genes in Chinese cabbage and confirm their responses to salt stresses. The comprehensive understanding of the physiological and molecular mechanisms of *Bra034084* and *Bra029784* can serve as an important genetic resource for the improvement in salinity stress tolerance and the yield of Chinese cabbage.

**Supplementary Materials:** The following supporting information can be downloaded at: https://ww w.mdpi.com/article/10.3390/antiox11091782/s1, Table S1: Chinese cabbage S1fa family genes cis-elements.

**Author Contributions:** A.A., J.G. and S.Z. conceived and designed the study. A.A. and S.Z. performed the experiment and wrote the manuscript. L.H., F.W. and L.-X.W. helped to collect the materials and revise the manuscript. J.G. reviewed the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** This study was supported by the Natural Science Foundation of Shandong Province (ZR2020MC145); the Natural Science Foundation of China (32172591); the Key R & D Program of Shandong Province, China (2019GHZ014); Modern Agricultural Industrial Technology System Funding of Shandong Province, China (SDAIT-02-022-04); Agricultural Science and Technology Innovation Project of SAAS (CXGC2022E08); the Agricultural Science and Technology Innovation Project of SAAS, China (CXGC2022D01).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
