The Tryptophan Decarboxylase in Solanum lycopersicum

Abstract

Melatonin plays an important role in plant growth, development, and environmental stress. In this study, a systematic analysis of tomato tryptophan decarboxylase (SlTrpDC), which is the first enzyme of melatonin biosynthesis, was conducted by integrating structural features, phylogenetic relationships, an exon/intron feature, and a divergent expression profile. The results determined that the tomato genome encoded five members (<i>SlTrpDC1</i>-<i>SlTrpDC5</i>). The phylogenetic relationships indicated that gene expansion was proposed as the major mode of evolution of the <i>TrpDC</i> genes from the different plant algae species to the higher plants species. The analyses of the exon/intron configurations revealed that the intron loss events occurred during the structural evolution of the TrpDCs in plants. Additionally, the RNA-seq and qRT-PCR analysis revealed that the expression of the <i>SlTrpDC3</i> was high in all of the tested tissues, while the <i>SlTrpDC4</i> and <i>SlTrpDC5</i> were not expressed. The expression patterns of the remaining two (<i>SlTrpDC1</i> and <i>SlTrpDC2</i>) were tissue-specific, which indicated that these genes may play important roles within the different tissues. No expression difference was observed in the tomato plants in response to the biotic stresses. This study will expand the current knowledge of the roles of the <i>TrpDC</i> genes in tomato growth and development.