No abstract

The contents of total phenolics (TPC), individual phenolic acid and antioxidant activities in the free and bound fractions of potato with different flesh colors were systematically investigated. The TPC and antioxidant capacity in the bound fraction was significantly lower than that in the free fraction. Chlorogenic acid, neochlorogenic acid, cryptochlorogenic acid, caffeic acid, p-coumaric acid and ferulic acid were detected in the free fraction with chlorogenic acid being the most predominant, accounting for 35.21–81.78% of the total content. Caffeic acid, p-coumaric acid and ferulic acid were detected in the bound fraction in the colored potato with caffeic acid being the major one. In the free fraction, the content of each individual phenolic acid had positive correlation with antioxidant activity. In the bound fraction, caffeic acid and p-coumaric acid showed positive correlation with antioxidant activity. This study promotes further understanding of the correlations among TPC, phenolic acids and antioxidant activity.

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Protein phosphorylation plays important roles in regulation of various molecular events such as plant growth and seed development. However, its involvement in starch biosynthesis is less understood. Here, a comparative phosphoproteomic analysis of two indica rice cultivars during grain development was performed. A total of 2079 and 2434 phosphopeptides from 1273 and 1442 phosphoproteins were identified, covering 2441 and 2808 phosphosites in indica rice 9311 and Guangluai4 (GLA4), respectively. Comparative analysis identified 303 differentially phosphorylated peptides, and 120 and 258 specifically phosphorylated peptides in 9311 and GLA4, respectively. Phosphopeptides in starch biosynthesis related enzymes such as AGPase, SSIIa, SSIIIa, BEI, BEIIb, PUL, and Pho1were identified. GLA4 and 9311 had different amylose content, pasting viscosities, and gelatinization temperature, suggesting subtle difference in starch biosynthesis and regulation between GLA4 and 9311. Our study will give added impetus to further understanding the regulatory mechanism of starch biosynthesis at the phosphorylation level.