TSAR1 and TSAR2 activate triterpene saponin production in Medicago truncatula

We identified two novel transcription factors ‘Triterpene Saponin Activation Regulator’ (TSAR) 1 and 2 that each activate a specific branch of saponin synthesis in M. truncatula. Therefore we generated three independent TSAR1 and three independent TSAR2 overexpression (OE) hairy root lines. As a control we raised three independent hairy root lines expressing a non-functional GUS gene. By qRT-PCR analyses and metabolite profiling of these lines, we found that TSAR1 OE leads to accumulation of non-haemolytic saponins whereas TSAR2 instigates accumulation of haemolytic saponins. To identify additional targets of TSAR1 and TSAR2 we carried out a genome-wide transcript profiling study by RNA-Seq.

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