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Desiccation tolerance (DT),the ability to survive loss of more than 90％ of cellular water (≤0.1 g H20 g 1 dry mass) for prolonged periods,is common in seeds (90％ of angiosperm species) but rare in vegetative tissues (0.04％ of land plants;reviewed in Gaff and Oliver,2013).Vegetative DT is more widespread in non-tracheophytes,being present in 25 species of algae,158 bryophytes species,and all lichens,but is rare in tracheophytes,being displayed in 64 pteridophyte and 135 angiosperm species (Gaff and Oliver,2013).Species with vegetative DT are commonly called resurrection plants.Non-tracheophytes have little by way of structural mechanisms to resist water loss and dehydrate rapidly.Protection against desiccation in such resurrection plants is constitutive.The evolution of vascular systems,waxy cuticles,and stomatal regulation in aerial tissues of sporophytes enabled better retention of water and enhanced the survival of such plants under waterdeficit stress.In most plants,this resulted in a loss of vegetative DT,but its retention in spores,pollen,and seeds.Over evolutionary time,DT was reacquired in vegetative tissues of angiosperm resurrection plants (ARPs) through a myriad of genetic changes in at least 13 separate lineages (Gaff and Oliver,2013).In such species,DT is acquired during dehydration by the induction of extensive protection mechanisms such that little repair is required on rehydration.