Fructan biosynthesis and degradation as part of plant metabolism controlling sugar fluxes during durum wheat kernel maturation

Abstract

Wheat kernels contain fructans, fructose based oligosaccharides with prebiotic properties, in levels between 2 and 35 weight % depending on the developmental stage of the kernel. To improve knowledge on the metabolic pathways leading to fructan storage and degradation, carbohydrate fluxes occurring during durum wheat kernel development were analyzed. Kernels were collected at various developmental stages and quali-quantitative analysis of carbohydrates (mono- and di-saccharides, fructans, starch) was performed, alongside analysis of the activities and gene expression of the enzymes involved in their biosynthesis and hydrolysis. High resolution HPAEC-PAD of fructan contained in durum wheat kernels revealed that fructan content is higher at the beginning of kernel development, when fructans with higher DP, such as bifurcose and 1,1-nystose, were mainly found. The changes in fructan pool observed during kernel maturation might be part of the signaling pathways influencing carbohydrate metabolism and storage in wheat kernels during development. During the first developmental stages fructan accumulation may contribute to make kernels more effective Suc sinks and to participate in osmotic regulation while the observed decrease in their content may mark the transition to later developmental stages, transition that is also orchestrated by changes in redox balance.

Linking Expression of Fructan Active Enzymes, Cell Wall Invertases and Sucrose Transporters with Fructan Profiles in Growing Taproot of Chicory (Cichorium intybus): Impact of Hormonal and Environmental Cues

“…Combining expression responses under two important environmental cues, i.e., N-starvation and cold-treatment, and two hormonal cues (ABA, ethylene precursor ACC) signaling drought (ABA) and water logging (ACC), respectively, this study provides insight into the dynamic regulation of source-to-sink sugar transport and fructan metabolism, and indicates that at whole plant level petioles display gene expression profiles distinct from leaf blade and taproot, respectively. Although enzyme activities were not determined, previous studies on chicory (Van Laere and Van den Ende, 2002) and on durum wheat (Cimini et al, 2015) have shown that FAZY expression at transcript level largely correlates with corresponding enzyme activities, suggesting that fructan enzymes are mainly controlled at the transcriptional level.…”

Durum Wheat Roots Adapt to Salinity Remodeling the Cellular Content of Nitrogen Metabolites and Sucrose

“…Total fructans were measured according to Morcuende et al (2004). Fructan classes were determined according to Cimini et al (2015). Starch and total fructans were expressed as glucose equivalents.…”

Structural Analysis of β-Fructofuranosidase from Xanthophyllomyces dendrorhous Reveals Unique Features and the Crucial Role of N-Glycosylation in Oligomerization and Activity

“…The unusual topology of the XdINV dimer suggests the possibly that it might be able to accommodate a putative polymeric substrate as it could be a mixed fructan with branched ␤(2-1)/ ␤(2-6) linkages (42,43) that, indeed, is degraded by XdINV. Fructans present in plants are a mixture of heterogeneous oligomers and polymers with a composition depending on the environment and the development state of the plant (38).…”