Oligosaccharide signalling molecules

The signalling potential of plant carbohydrates had largely been overlooked until the last 2 decades. Whether trehalose- and sucrose-derived compounds, or oligosaccharides emanating from cell wall fragmentation, carbohydrate signals are thought to play key roles in plant growth and development at one level, and in activating plant defences against microbial infection at another. However, the literature is less than definitive, in many cases, about how in vitro observations correlate, or not, with true in vivo function. Nonetheless, a better understanding of the developmental regulation, allelopathic and defence-inducing properties of 'oligosaccharin' signalling carbohydrates offers scope not only for better understanding plant biology per se, but also presents novel opportunities for commercial exploitation. This chapter highlights oligosaccharide structures that have been reported to possess the properties of signal-ling molecules; although in many cases physiological relevance has not been demonstrated there is potential for exploitation. This chapter outlines the main classes of plant-derived oligosaccharide molecules that have been reported to possess signalling capabilities. Comment is made on reports of the physiological function and/or the action of such compounds when fed exogenously. In many cases, whilst biological activity has been demonstrated its relevance to physiological function remains to be established.