Raffinose family oligosaccharides (RFOs) are α-galactosyl extensions of sucrose (α-1,6-Galn-Suc, 1≤n≤13). They are the most abundant oligosaccharides in the plant kingdom and many RFO-producing plants are of economic importance including cucurbits, mints, legumes, olives, grapes, and pines. As primary photosynthetic products RFOs are jacks of all trades, fulfilling diverse physiological functions, such as storage and translocation of carbon and protection against environmental stresses. Interestingly, not all RFO plants use their RFOs for all of the above-mentioned functions. We have shown, for instance, that (i) sweet basil (Ocimum basilcum) uses the RFO-tetrasaccharide stachyose as phloem translocate but stores starch in its leaves, (ii) Japanese artichoke (Stachys sieboldii) both translocates and stores stachyose, and (iii) mare's tail (Hippuris vulgaris) translocates Suc but stores stachyose.
To further highlight the chemical diversity of water-soluble carbohydrates in plants we have also been studying the biochemistry and physiology of a variety of additonal alternative carbohydrates such as certain sucrosyl-oligosaccharides (e.g. fructans), sugar alcohols, and cyclitols. We are currently involved in the elucidation of the biosynthetic pathway of the trisaccharide, gentianose, in Gentiana spec. (gentian) and that of the heptitol volemitol in Primula x polyantha (polyanthus).