Scanning electron microscopy of desiccation-tolerant and -sensitive microspore-derived embryos of Brassica napus L.

Desiccation tolerance can be induced in microspore-derived embryos of Brass ica napus L. by application of abscisic acid (ABA). Scanning electron micro scopy was employed to study and compare desiccation-tolerant and -sensitive microspore-derived embryos. The external surface of those desiccated embry os in which desiccation tolerance had been induced was uniformly shriveled due to severe dehydration, and their internal tissue system was well preser ved. In contrast, in desiccation-sensitive embryos, dehydration caused tear ing of the epidermis and collapse of the internal tissue system. After the desiccated embryos had been rehydrated, the size and external morphology of the desiccation-tolerant ones recovered to the pre-desiccation state withi n 1 day, whereas the sensitive ones did not recover or remained shriveled. The effect of ABA on the induction of desiccation tolerance is discussed.