Label-free quantitative proteomic analysis determines changes in amino acid and carbohydrate metabolism in three cultivars of Jerusalem artichoke tubers

Abstract

Jerusalem artichoke (JA) tubers are an important bio-economy developing crop because of its invaluable bioproducts in both food and biofuel aspects. However, the molecular mechanism of its tuberization, and the differences among different cultivars have been little studied to date. Therefore, here we selected PJA, DJA, and HJA cultivars of JA tubers, showing variations in their tuber epidermal pigmentation, underground tuberization, and inulin content. A comparative proteome analysis led to the identification of 402 proteins in the tubers of which 114 were significantly modulated among different cultivars. Gene Ontology (GO) analysis showed proteins related to the biosynthesis of amino acids and carbohydrate metabolism were differentially modulated in the tubers of three cultivars. Results from the inulin content measurement and proteome analysis suggest that Sucrose:sucrose 1-fructosyltransferase (1-SST) prioritizes inulin biosynthesis rather than rate-limiting enzyme fructan:fructan 1-fructosyltransferases (1-FFT). Furthermore, we confirmed the relationship between transcript-protein expression levels was in discord within inulin biosynthesis enzymes 1-SST and 1-FFT with the terms in previous RT-qPCR results using the same tubers. Our data represent the first report of comparative tuber proteome profiling of different JA and provide the metabolic and molecular basis for understanding carbohydrate metabolism in the tuber tissue.