Genome-wide Identification and Expression Pattern Analysis of Zinc-finger Homeodomain Transcription Factors in Tomato under Abiotic Stress

Members of the zinc-finger homeodomain (ZF-HD) family play a key role in the control of plant growth and development, which are involved in plant responses to stress. Although many functional studies of this gene family have been performed in different plants, the features of this family in tomato (Solanum lycopersicum) remain unknown. In this study, we identified 22 ZF-HD genes in the tomato genome and classified them into seven groups located on six chromosomes. Expression of 15 ZF-HD genes in tomato was studied in different tissues to identify their putative functions in many aspects of plant growth and development. Based on previous phylogenetic analyses in arabidopsis (Arabidopsis thaliana), our results showed that some tomato SL-ZH (S. lycopersicum zinc-finger homeodomain) genes cluster into the same neighbor-joining (NJ) branch as arabidopsis, indicating that these genes may share similar structures and functions in these plants. Gene expression analysis demonstrated that the tomato ZF-HD gene may be involved in abiotic stress responses, the SL-ZH13 gene in cold stress and the SL-ZH15 gene in drought stress; almost all tomato ZF-HD genes were responsive to salt stress, except for SL-ZH7, -ZH8, and -ZH22. However, the structures and functions of unknown groups require further research. In conclusion, this study identified tomato ZF-HD genes and analyzed their gene structures, subfamily distribution, and expression characteristics. These experiments combined with previous research findings reveal significant information and insight for future studies on the agronomic features and stress resistance in tomato.