ABA Participates in Salt Stress-Induced Anthocyanin Accumulation by Stimulating the Expression of LrMYB1 in Lycium Ruthenicum Murr.

Lycium ruthenicum Murr. (L. ruthenicum) is a valuable medicinal source with a high content of anthocyanin. Most of the previous study were focused on the regulation process of anthocyanin biosynthesis in fruit development, the mechanism of anthocyanin accumulation in L. ruthenicum seedlings has rarely been reported. In the present study, anthocyanin accumulation in L. ruthenicum seedlings induced by salt stress was studied, and the expression of LrMYB1 and phytohormone abscisic acid (ABA) played a role in this process. Our results showed that LrMYB1 was stimulated by salt stress, and the expression of LrMYB1 also had a positive correlation with the expression of LrDFR and LrANS, which play key roles in anthocyanin biosynthesis in L. ruthenicum, suggesting that LrMYB1 is a critical regulator in anthocyanin biosynthesis. Compared with the wild-type seedlings, LrMYB1 RNA interference lines accumulated less anthocyanins under salt stress, which confirmed the role of LrMYB1 in anthocyanin biosynthesis in the L. ruthenicum seedlings response to salt stress. Furthermore, ABA content was sharply increased in L. ruthenicum seedlings after 1/2 days of salt stress. Exogenous ABA could also stimulate the expression of LrMYB1 and structural genes in anthocyanin biosynthesis pathway but could not induce more anthocyanin biosynthesis and structural gene upregulation in the LrMYB1 RNA interference lines. These results may imply that ABA could induce anthocyanin biosynthesis under salt stress by upregulating LrMYB1. This study provides valuable insights into the molecular mechanisms of anthocyanin biosynthesis in L. ruthenicum seedlings and extend the understanding of the regulatory mechanism of MYB transcription factor and ABA on anthocyanin accumulation in L. ruthenicum. We provide new details regarding the molecular mechanism by which ABA participate in anthocyanin biosynthesis via modulate the expression of LrMYB1 in Lycium ruthenicum Murr. seedlings response to salt stress.