Setaria viridis isolate:A10.1 Transcriptome or Gene expression

Setaria viridis (green foxtail millet), a short life-cycle C4 plant in the Gramineae, serves as aresilient crop that provides good yield even in dry and marginal land. Although S. viridis hasbeen studied extensively in the last decade, molecular mechanisms of insect resistance remainunstudied. The aim of our research is to expose the molecular mechanisms of S. viridis defenseresponses against aphids. To address this, we performed a metabolic analysis and discovered thatthe plants synthesize the indole-derived compounds tryptamine, and serotonin. To identify thepotential genes that are involved in serotonin biosynthesis, we conducted a transcriptomeanalysis and identified several predicted S. viridis Trp decarboxylases (TDC1) and cytochromeP450 tryptamine 5-hydroxylase (T5H) genes that were upregulated in response to aphid feeding.The function of TDC1 (Sevir.6G066200) gene was validated by using virus-induced genesilencing in Setaria italica, which showed a reduction in serotonin levels as well as ectopicexpression and detection of tryptamine accumulation in Nicotiana tabacum. To validate theproperties of tryptamine and serotonin on aphids, we ectopic express SvTDC1 and rice OsT5Hgenes in Nicotiana tabacum, and tested the effect on Myzus persicae aphids. The resultsdemonstrated that the accumulation of serotonin confers susceptibility to aphids. Therefore,biosynthesis and regulation of serotonin is important for defense responses in Setaria and mightprove valuable for developing insect-resistant cultivars.