Molecular And Physiological Mechanism Research Of Anthocyanin Accumulation In Purple Sweet Potato Tuberous Root

Sweet potato (Ipomoea batatas (L) Lam.) is the sixth important food crops around the world, and its planting area and production in our country rank the first of the world. Purple sweet potato, a special cultivar of sweet potato, has lots of anthocyanin in its tuberous root. Plant anthocyanin is a kind of water-soluble natural pigment with many health-promoting benefits. So research on the metabolism of purple sweet potato anthocyanin has become the hotspots. At present, the researchs on sweet potato anthocyanin are still in its infancy, the mechanism of anthocyanin biosynthesis and regulation in sweet potato is not clear, lacking large-scale proteomics study. This study chose the tuberous roots of sweet potato that were in quick growing period as the materials, and compared three different protein extraction methods to select the optimum method for tuberous root of sweet potato. Then we separated the proteins of different sweet potato cultivars by two-dimensional electrophoresis (2-DE), and analyzed the differentially expressed proteins using ImageMaster 7.0 software. More than 800 proteins were detected in reproducibly 2-D gels, of which 50 proteins showed significant differences, including 39 up-regulated and 11 down-regulated in purple sweet potato, were identified by MALDI-TOF/TOF-MS.48 proteins were successfully identified and 2 had no match in the NCBI database. The results showed most of the identified were participated in starch metabolism and glycolysis pathway according to their functions. Moreover, we verified the mRNA expressions of SP, PAL, CHS, F3H, DFR, ANS, UFGT and VP24 using semi-PCR and real time PCR, and also checked the physiology level. Combination of protein, mRNA and physiology level, a possible molecular regulation network of anthocyanin metabolism was revealed as followings:1. According to the analysis of SP, PGM protein levels, physiological levels and SP transcription level in purple sweet potato, we found that the degradation of starch could provide the precursors for anthocyanin synthesis.2. VP24 was firstly discovered in anthocyanin-producing vacuoles of sweet potato tuberous root. VCaB42 was found to be related to the formation of vacuole. These two proteins were found more accumulated in purple sweet potato in our study, revealing the VP24 way is one of the way that anthocyanin transport through and became stored in vacuole.3. Other proteins, such as 14-3-3 family, GME, etc., constitute the complex anthocyanin metabolic regulation network in purple sweet potato tuberous root.This study provides a new point of view and certain help for the further research of anthocyanin synthesis regulation mechanism in sweet potato tuberous root.