Identification And Stress Tolerance Analysis Of Conserved MicroRNAs In Tomato

microRNA (miRNA) is an important regulatory factor in various physiological processes of organisms. At present, a large amount of miRNAs were discovered in plants. Many of these miRNAs were proven to be involved in the responding regulation of multiple stresses, such as pathogen infection, salt response, drought response, and so on. Though tomato is an important economic crop as well as a model plant, there were only a few reports about tomato miRNAs, especially stress related tomato miRNAs.The following results were obtained in this study.Our research obtained14novel tomato miRNAs and56target genes. These targets were mainly involved in metabolism, transmembrane transport, stress response, and transcription regulation. Using real-time PCR verification, ten of the14miRNAs were proven to express in tomato, including miR157a, miR157b, miR170a, miR170b, miR170c, miR398, miR828, miR2111,miR2118a and miR2118b.The expression patterns of miR172and miR398were detected in different tissues and under various stresses. The expression levels of the two miRNAs were higher in stems than in roots and leaves. miR172and miR398had different expression types responding to different stresses, including pathogen infection, salt stress, drought stress, and abscisic acid (ABA) treatment. These results might suggest a role of miR172and miR398in the regulation of biotic and abiotic stress reponses in tomato.To further elucidate the function of miR172and miR398, their genes were cloned in tomato and the overexpression vectors were constructed. After the transformation of tobacco, the higher expression levels of miR172and miR398inhibited the levels of their stress-related targets in transgenic tobacco. These results suggested that miR172and miR398were involved in the regulation of stress-related target genes. The two miRNAs might play a crucial role in the stress response of tomato.This research was a supplement to the discovery of tomato miRNAs. It provided the basis for the regulatory mechanisms of tomato stress responses.