Influence Of Potassium Fertilizer Application On Anthocyanin Accumulation Of Purple-fleshed Sweetpotato Storage Root

Sweetpotato(Ipomoea batatas(l.) Lam.) belongs to the family Convolvulaceae. Purple-fleshed sweetpotato is famous for its purple flesh, which is one special type of sweetpotato varieties. Being rich in starch, protein, zinc, selenium and vitamins and other nutrients, purple-fleshed sweetpotato storage root also contains cyanine glycosides pigments. Anthocyanin biosynthesis and accumulation of storage root of purple-fleshed sweetpotato are regulated by major factors, including potassium, which is an important regulatory factor. Potassium is an enzyme activator in a variety of plant growth and development, which can affect the accumulation of plant sugars through photosynthesis, and thus affect anthocyanin synthesis. In order to make clear anthocyanin metabolic mechanism of sweetpotato and provide ideas for high-quality purple sweetpotato breeding, this paper studied the effects of potassium on the purple-fleshed sweetpotato anthocyanin accumulation and synthesis-related gene relative expression.In this experiment, the purple-fleshed sweet potato “Xuzishu No.1” and “Xuzishu No.3”used as test materials. Under different potassium treatments, anthocyanin accumulation, quality traits, and synthesis-related gene relative expression of purple-fleshed sweetpotato were analyzed. The results showed that potassium treatment could increase the storage root yield, anthocyanin, starch, soluble sugar and reducing sugar content, and also could promote the relative expression of synthesis-related genes involved in anthocyanin biosynthesis. Our study found that, after potassium treatment, CHS, CHI, F3 H, DFR, ANS, UFGT relative expression level in “Xuzishu No.1” and “Xuzishu No.3” storage root significantly larger than no-potassium treatment, indicating that the potassium treatment could influence the relative expression of synthesis-related genes involved in anthocyanin biosynthesis. The relative expression of F3 H,DFR,UFGT gene were significantly affected by potassium. Potassium significantly promoted ANS and UFGT gene relative expression in periods of high anthocyanin highly accumulation period. These two genes also had the high relative expression levels in Xuzishu No.3 storage root. All these below showed that ANS gene was more important than other genes in anthocyanin synthesis. The relative expression of ANR gene had a higher level in Xuzishu No.1 than in Xuzishu No.3, indicating that ANR gene maybe negatively regulated anthocyanin biosynthesis.Our study also showed that soluble sugar content decreased when anthocyanin highly accumulated. Anthocyanin content negatively correlated with soluble sugar content, because anthocyanin synthesis needed a lot of soluble sugar.