WRKY34 positively regulates yield, lignan biosynthesis and stress tolerance in .

Yield potential, pharmaceutical compounds production and stress tolerance capacity are 3 classes of traits that determine the quality of medicinal plants. The autotetraploid has greater yield, higher bioactive lignan accumulation and enhanced stress tolerance compared with its diploid progenitor. Here we show that the transcription factor WRKY34, with higher expression levels in tetraploid than in diploid , has large pleiotropic effects on an array of traits, including biomass growth rates, lignan biosynthesis, as well as salt and drought stress tolerance. Integrated analysis of transcriptome and metabolome profiling demonstrated that expression had far-reaching consequences on both primary and secondary metabolism, reprograming carbon flux towards phenylpropanoids, such as lignans and flavonoids. Transcript-metabolite correlation analysis was applied to construct the regulatory network of WRKY34 for lignan biosynthesis. One candidate target 4CL3, a key rate-limiting enzyme of lignan biosynthesis as indicated in our previous study, has been demonstrated to indeed be activated by WRKY34. Collectively, the results indicate that the differentially expressed WRKY34 has contributed significantly to the polyploidy vigor of , and manipulation of this gene will facilitate comprehensive improvements of herb.