Abstract
This research aimed to investigate the cellular alterations during the loss and re-establishment of desiccation tolerance (DT) in germinated Sesbania virgata seeds. The loss of DT was characterized in germinated seeds with increasing radicle lengths (1, 2, 3, 4 and 5 mm) when subjected to dehydration in silica gel, followed by rehydration. To re-establish DT, the germinated seeds were incubated for 72h in polyethylene glycol (PEG, -2.04 MPa) with or without ABA (100 μM) before dehydration in silica gel. Cell viability was assessed by seedling survival, and DNA integrity was evaluated by gel electrophoresis. Seeds with 1 mm radicle length survived dehydration to the original moisture content (MC) of the dry seed (approximately 10%). PEG treatment was able to re-establish DT, at least partially, with 2, 3 and 4 mm but not in 5 mm radicle lengths. Germinated seeds treated with PEG+ABA performed better than those treated only with PEG, and DT was re-established even in germinated seeds with a 5 mm radicle length. Among the PEG-treated germinated seeds dehydrated to 10% MC, DNA integrity was maintained only in those with a 1 mm radicle length.
Highlights
Desiccation tolerance corresponds to the ability to survive under intense protoplasmatic dehydration, a phenomenon that is common in the plant kingdom with regard to pteridophytes, lichens, pollen and the seeds of many angiosperms
Many processes at the physiological, cellular and molecular levels that occur during the loss of desiccation tolerance (DT) in germinated orthodox seeds may be similar to those responsible for the desiccation sensitivity exhibited by recalcitrant seeds (FARRANT, 2010)
Seeds with 1 mm long radicles maintained a high percentage of survival (95%) when dehydrated to the original moisture content (MC)
Summary
Desiccation tolerance corresponds to the ability to survive under intense protoplasmatic dehydration, a phenomenon that is common in the plant kingdom with regard to pteridophytes, lichens, pollen and the seeds of many angiosperms. With the completion of germination, the emerged radicle is typically the first organ to lose the ability to tolerate dehydration, followed by the hypocotyl and cotyledons. Because of their sensitivity to dehydration, germinated orthodox seeds are similar to recalcitrant seeds (BOUDET et al, 2006) and can be used as a tool in studies of recalcitrance. Many processes at the physiological, cellular and molecular levels that occur during the loss of DT in germinated orthodox seeds may be similar to those responsible for the desiccation sensitivity exhibited by recalcitrant seeds (FARRANT, 2010)
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