Effect of NAC154 transcription factor overexpression on the field grown poplar stem wood metabolome

Several xylem-associated regulatory genes have been identified that control processes associated with wood formation in poplar. Prominent among these are the NAC domain transcription factors (NACs). We evaluated the putative involvement of Populus NAC154, a co-ortholog of the Arabidopsis gene SND2, as a regulator of secondary biosynthetic processes in stem internode tissues by interrogating methanol:water extracts from control and transgenic trees. Comprehensive untargeted metabolite profiling was accomplished with a liquid chromatography-mass spectrometry platform that utilized two different chromatographic supports (HILIC and reversed phase) and both positive and negative ionization modes. Evaluation of current and previous year tissues provided datasets for assessing the effects of NAC154 overexpression in wood maturation processes. Phenolic glycoside levels as well as those of oligolignols, sucrose and arginine were modulated with phenotypic and chemotypic traits exhibiting similar trends. Specifically, increased levels of arginine in the NAC154 overexpressing tissues supports a role for the transcription factor in senescence/dormancy-associated processes.