The transformation of desiccoplasts into etioplasts and the parallel appearance 
of protochlorophyllide (Pchlide) forms were observed with transmission electron 
microscopy and 77K fluorescence spectroscopy, when air-dried detached leaves of 
the poikilochlorophyllous desiccation tolerant plant Xerophyta humilis were 
floated in water in the dark. After 1 week of rehydration, pregranal plastids 
with newly synthesized prothylakoid (PT) lamellae and mainly non-photoactive 
Pchlide forms developed, while etioplasts with prolamellar bodies (PLBs) and 
photoactive, 655nm emitting Pchlide form accumulated primarily in the basal leaf 
regions after 2 weeks of regeneration. When these latter leaves were illuminated 
with continuous light for 3 days, the etioplasts transformed into regular 
chloroplasts and the fluorescence emission bands characteristic of green leaves 
appeared. These results show that, upon rehydration, the dehydrated chlorenchyma 
cells are able to regenerate pregranal plastids and etioplasts from 
desiccoplasts in the dark, which can transform into regular chloroplasts when 
they are illuminated. This means that the differentiation of pregranal plastids 
and etioplasts and their greening process is a basic property of fully 
differentiated cells of X. humilis. Consequently, these processes are not merely 
characteristic for seedlings with meristematic and differentiating young 
tissues.