Growth and transcriptome analysis of tomato under seawater stress

Abstract

The tomato industry has been seriously affected by continuous soil salinization and seawater irritation. This study analyzed the salt tolerance mechanism of tomato from physiological and molecular aspects and screened out the salt tolerance genes; this information provides a foundation for future research on tomato salt tolerance and environmental adaptability. In this study, tomato was used as the experimental material, and treated with seawater accounted for 0%, 10%, 20%, or 30% of the nutrient solution volume respectively. The results showed that when the seawater percentage was less than 20%, it had little effect on the growth of tomato; when the seawater percentage was more than 20%, it could severely inhibit tomato growth, thereby affecting the ion balance in plants. The results showed that 33,810 unigenes were obtained after transcriptome high-throughput sequencing and assembly. In total, 31,631 unigenes were successfully annotated by comparison of the obtained unigenes with six gene databases. According to the Gene Ontology (GO) database, unigenes in the tomato transcriptome could be roughly divided into three categories (biological process, cellular component, and molecular function) with 45 branches. Analyzing genetic differences revealed that 509 unigenes were significantly differentially expressed under seawater stress, among which 40.67% were up-regulated and 59.33% were down-regulated. Moreover, we also found that the differentially expressed genes (DEGs) were mainly enriched in six pathways: growth, response to stimulus, signaling, membrane, transcription factor activity and protein binding. The expression profiles of the selected DEGs in the samples were characterized and verified by qRT-PCR. These DEGs and metabolic pathways may play an important role in salt tolerance of tomato. The functional characteristics of these genes and pathways will provide a new target for improving salt tolerance of tomato through gene regulation.