Genome-Wide Identification and Expression Analysis of Cysteine-Rich Polycomb-like Protein (CPP) Gene Family in Tomato.

The cysteine-rich polycomb-like protein (CPP) gene family is a class of transcription factors containing conserved cysteine-rich CRC structural domains that is involved in the regulation of plant growth and stress tolerance to adversity. Relative to other gene families, the CPP gene family has not received sufficient attention. In this study, six were identified for the first time using the most recent genome-wide identification data of tomato. Subsequently, a phylogenetic analysis classified into four subfamilies. The analysis of -acting elements in the promoter indicates that are involved in plant growth and development and also stress response. We present for the first time the prediction of the tertiary structure of these proteins using the AlphaFold2 artificial intelligence system developed by the DeepMind team. Transcriptome data analysis showed that were differentially expressed in different tissues. Gene expression profiling showed that all except were up-regulated under drought stress; , and were up-regulated under cold stress; and were up-regulated under salt stress; all were up-regulated under inoculation with ; and , , and were up-regulated under inoculation with . We performed a virus-induced gene silencing experiment on , and the results indicated that was involved in the response to drought stress. Finally, we predicted the interaction network of the key gene , and there was an interaction relationship between and 10 genes, such as and . The positive outcome showed that responded to environmental stress. This study provides a theoretical and empirical basis for the response mechanisms of tomato in abiotic stresses.