Giant reed (Arundo donax L.): A weed plant or a promising energy crop?

Giant reed (Arundo donax) is a perennial rhizomatous grass which is widely diffused in subtropical and warm temperate regions. From its native area, probably Eastern Asia, it has been dispersed all over the world by humans who use it for multiple purposes such as roof thatching, reeds in woodwind instruments, fishing rods, etc. Its spontaneous and rapid growth allows A. donax to be considered as an invasive weed. But more recently, due to its high biomass production and great adaptability to marginal land, it is being seen as one of the most promising energy crops for lignocellulosic bioethanol production. A. donax is a sterile plant because it is a hybrid with uneven ploidy or triploid specie. Therefore, its propagation is strictly agamic by rhizome fragmentation and sprouting from cane nodes. The lack of sexual reproduction is a negative characteristic when we consider A. donax as an energy crop, since it makes genetic improvement difficult, and this is further limited by the absence of genome sequence information and the lack of specific molecular tools. In this review we will summarize and discuss recent data on A. donax, specifically its origins, genetics and possible utilization as a source of biomass.   Key words: Arundo donax, vegetative propagation, polyploidy, energy crop, biomass, ethanol fermentation.