F-box genes play an important role in the growth and development of plants, but there are few studies on its role in a plant’s response to abiotic stresses. In order to further study the functions of F-box genes in tomato (Solanum lycopersicum, Sl), a total of 139 F-box genes were identified in the whole genome of tomato using bioinformatics methods, and the basic information, transcript structure, conserved motif, cis-elements, chromosomal location, gene evolution, phylogenetic relationship, expression patterns and the expression under cold stress, drought stress, jasmonic acid (JA) treatment and salicylic acid (SA) treatment were analyzed. The results showed that SlFBX genes were distributed on 12 chromosomes of tomato and were prone to TD (tandem duplication) at the ends of chromosomes. WGD (whole genome duplication), TD, PD (proximal duplication) and TRD (transposed duplication) modes seem play an important role in the expansion and evolution of tomato SlFBX genes. The most recent divergence occurred 1.3042 million years ago, between SlFBX89 and SlFBX103. The cis-elements in SlFBX genes’ promoter regions were mainly responded to phytohormone and abiotic stress. Expression analysis based on transcriptome data and qRT-PCR (Real-time quantitative PCR) analysis of SlFBX genes showed that most SlFBX genes were differentially expressed under abiotic stress. SlFBX24 was significantly up-regulated at 12 h under cold stress. This study reported the SlFBX gene family of tomato for the first time, providing a theoretical basis for the detailed study of SlFBX genes in the future, especially the function of SlFBX genes under abiotic stress.

Sulfur is an intermediate element in plants. It plays an important role in the growth and development of plants. Plant roots absorb sulfate from their external environment and produce cysteine under the catalysis of cysteine synthase. Cysteine is a synthetic precursor of sulfur-containing metabolites and critical molecules including glutathione (GSH), methionine, vitamins, coenzymes, and antioxidants. It also plays a central role in plant stress resistance. In this study, we identified the Cys family genes in tomato and analyzed the expression of SlCys genes under cold stress. A bioinformatics analysis showed that the SlCys gene promoters were rich in cis-acting elements related to stress response. Transcriptome data analysis and qRT-PCR (real-time fluorescent quantitative polymerase chain reaction) experiments showed that SlCys5 may be the key gene in the Cys gene family for cold tolerance in tomato. After cold stress treatment, the SlCys5-silenced tomato plants were more sensitive to cold stress, and wilting was more severe than in control plants. Thus, SlCys5 is a positive regulator of cold tolerance in tomato. In this study, we elucidated the evolutionary pattern and functional differentiation of the Cys gene family in tomato, deepening our understanding of the regulatory mechanism of cold stress tolerance in plants.

CSN5 is one of the subunits of the COP9 signalosome, which can regulate plant life activities by participating in the ubiquitination process. It is also positively correlated with JA signal intensity in plants and regulates JA-dependent plant defense responses. In this study, a total of three CSN5 family genes were identified in tomatoes and a systematic bioinformatics analysis was performed to clarify their similarities and differences. In addition, by analyzing the publicly available transcriptome data and qRT-PCR experiments, it was found that SlCSN5-2 and SlCSN5-3 were up-regulated under gray mold disease stress, and the potential key gene SlCSN5-3 was up-regulated most significantly. Silencing SlCSN5-3 in tomatoes resulted in reduced resistance to gray mold disease, and it was clear that SlCSN5-3 positively regulates tomatoes’ resistance to gray mold disease through the JA pathway.