About this Research Topic
Fructans (fructosyl extension of sucrose) and Raffinose Family Oligosaccharides (RFOs: galactosyl extensions of sucrose) are important classes of water soluble carbohydrates in plants. While fructans occur at higher levels in about 15% of flowering plants, the smallest RFO, raffinose, is more ubiquitous in higher plants. The accumulation of both carbohydrate types is often associated with abiotic and biotic stress responses.
Besides their role as reserve carbohydrates, membrane stabilizers, osmoregulators and stress tolerance mediators, it was recently proposed that smaller representatives of these sugars may contribute to cellular redox balances or act as phloem-mobile signaling compounds under stress. Curiously, so called non-fructan accumulating plants or plants that only contain marginal amounts of raffinose often express hydrolytic enzymes (FEHs: fructan exohydrolases; galactosidases) that are able to tackle these substrates. However, the inability to degrade sucrose (defective invertases) might be more important than their ability to degrade fructans or RFOs.
Here, we welcome papers on all aspects of fructan and RFO metabolism and signaling, with special focus on putative alternative roles for the sugars, FEHs, defective invertases and galactosidases involved, connections with sucrose metabolism, sugar signaling and hormone signaling, and the possible contribution of all these processes to cellular reactive oxygen species homeostasis under stress.
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