Evidence for the biological function of miR403 in tomato development

• miR403 in development.
• miR403 cooperate with miR168.
• AGO1 cooperate with AGO2.

miRNAs are important regulators in plants, animals and worms. AGO proteins bound to miRNAs by recognition of complimentary sequence to repress expression of target genes. In plants, two miRNAs, miR168 and miR403 were identified as repressors of AGO1 and AGO2 respectively. miR168 was confirmed to play a key role in development of plants. However, the function of miR403 had not been illuminated yet. Previously, we investigated the cleavage of SlAGO2at the complimentary sequence of miR403. In this study, over-expression of miR403 in tomato showed flowering delay, leaf morphology and resistance to ABA during germination. Besides, two of transgenic plants exhibited defects in shooting meristem maintenance which were similar as the defects observed in 4m-SlAGO1s transgenic plants. Decrease of SlAGO2and increase of SlAGO1A/1Bwere found in miR403 transgenic plants. Moreover, miR156, miR159 and miR394 were accumulated in miR403 transgenic plants. Our results revealed the function of miR403 in tomato development via affecting expression ofSlAGO2, which might further alter the homeostasis between SlAGO1A/1Band miR168, then influence the balance of down-stream miRNA.