Regulation of the aurantio-obtusin accumulation by StTCP4.1-mediated StDA1-StHDR1 module inSenna toraseeds

Abstract

AbstractSenna tora(S. tora) is a commonly used Chinese medicinal plant due to the presence of the bioactive compounds anthraquinones in its mature seeds. Seed size is an important factor that affectS. torayield quantity and quality. However, the mechanism regulating seed size and aurantio-obtusin biosynthesis inS.torais still unclear. In this study, we identified the ubiquitin receptor StDA1 inS.torathat served as a negative regulator to seed formation and limited seed enlargement. Antisense overexpression of StDA1 led to larger seeds inS. toraand promoted the accumulation of aurantio-obtusin. In contrast, overexpression of StDA1 inS.toraresulted in a relative decrease in aurantio-obtusin accumulation. Moreover, StDA1 can directly bind to StHDR1and regulate its degradation through the 26S proteasome to regulate seed size and aurantio-obtusin accumulation. We also found that the StDA1-StHDR1 module is responsive to the MeJA via StTCP4.1, which in turn affects the accumulation of aurantio-obtusin. Overall, we have identified a protein complex that regulates the accumulation of aurantio-obtusin, StTCP4.1-StDA1-StHDR1, as a potential target for improvingS.torayield quantity and quality.