Abstract
ABSTRACT The aim of this study was to evaluate DNA integrity and to identify ultrastructural changes in the primary root of Peltophorum dubium seeds subjected to drying, since these changes may reflect the germination capacity. Seeds were germinated and were dehydrated when reached 1 mm in length of the primary root, until reaching different moisture contents, being then rehydrated and evaluated in relation to survival. After this procedure, different points of interest (control, 20% and 10% moisture content) were selected to evaluate DNA and cell ultrastructure integrity in order to detect possible cellular changes in primary roots after dehydration. When dried down to 32% moisture, there was no influence on the growth resumption of the germinated seeds, but when they were dehydrated to 20% moisture, the survival was reduced to 67%, reaching nullity in the survival with drying to 8% moisture. By the evaluation of ultrastructural changes in root cells, it was observed that drying to approximately 20% moisture content marked the onset of damages by desiccation, both physiologically and ultrastructurally. Drying to levels close to 10% moisture content was not only responsible for total disorganization and rupture of membranes, but also promoted intracellular collapse. Loss of genomic DNA integrity was observed during drying.
Highlights
The phenomenon of desiccation tolerance in any system can be assessed by the extent of cell survival during dehydration and subsequent rehydration
The maintenance of the genetic information contained in DNA is essential for the cell survival and it is proposed that the desiccation tolerance in seeds depends on the capacity to repair damages to the genomic DNA when the embryo is dehydrated and later rehydrated
To evaluate the gradual loss of desiccation tolerance (DT) in germinated seeds of Peltophorum dubium in order to use them as a model for studies concerning the molecular aspects involved in this process, these were analyzed regarding survival after the gradual removal of water
Summary
The phenomenon of desiccation tolerance in any system can be assessed by the extent of cell survival during dehydration and subsequent rehydration. Among the several known protection mechanisms, it has been reported that desiccation tolerance depends on the ability to repair genomic DNA damage and maintain the integrity of the seeds’ anatomical structures during drying (Osborne and Boubriak, 1997; Moore et al, 2009). The maintenance of the genetic information contained in DNA is essential for the cell survival and it is proposed that the desiccation tolerance in seeds depends on the capacity to repair damages to the genomic DNA when the embryo is dehydrated and later rehydrated. Tolerance can be achieved through mechanisms that incorporate one of the two alternatives, i.e. cell protection or recovery (Oliver, 1996; Osborne et al, 2002)
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