**5. Conclusions**

In the present study, we identified and characterized ten *SlBAGs* at tomato genome level, which were supported by structural characteristics of the SlBAG proteins and genes, as well as by phylogenetic analysis. Large-scale expression of these *SlBAGs* by qRT-PCR further revealed tissue- and abiotic stress-specific expression patterns, which might be related to plant growth and abiotic stresses. Additionally, *SlBAG9* conferred sensitivity to osmotic stress when heterologously expressed in transgenic Arabidopsis. The enhanced sensitivity was ascribed to the decreased expression of several stress and ABA-responsive genes, the increased oxidative damage as well as the decreased ROS scavenging capability in the *SlBAG9*-overexpressing plants. Besides, it is worth noting that this study not only provide a foundation for understanding the functions of *SlBAG* gene family but also has important guiding significance for its final application in molecular resistance breeding.

**Supplementary Materials:** The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/antiox11030598/s1, Figure S1: Cis-elements components in the promoters of tomato *SlBAG* genes; Figure S2: The increased sensitivity of *SlBAG9*-overexpressing Arabidopsis exposed to mannitol, NaCl, and ABA stress; Table S1: Primers used in this study for qRT-PCR analysis; Table S2: Information of 10 *SlBAG* genes from multiple data sources; Table S3: The cis-element of *SlBAG* gene promoters.

**Author Contributions:** H.D. and H.J., Conceptualization; H.J., Y.J., J.S. and Y.W., investigation; H.J., X.L. and P.X., formal analysis; H.D., writing. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the National Natural Science Foundation of China (grant no. 32172546) and the Natural Science Foundation of Jiangsu Province (BK20191437).

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

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available in the article and its Supplementary Materials.

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