Re-induction of desiccation tolerance after germination of Cedrela fissilis Vell. seeds

Abstract

This work aimed to characterize the re-induction of desiccation tolerance (DT) in germinated seeds, using polyethylene glycol (PEG 8000). Cell changes were investigated through cytological assays (cell viability and transmission electronic microscopy) as well as DNA integrity during loss and re-establishment of DT. The loss of DT was characterized by drying germinated seeds with different radicle lengths (1, 2, 3, 4 and 5 mm) in silica gel, decreasing the moisture content to ten percentage points intervals, followed by prehumidification (100% RH / 24 h) and rehydration. To re-induce DT, germinated seeds were treated for 72 h with PEG (-2.04 MPa) and PEG (-2.04 MPa) + ABA (100 μM) before dehydration. Germinated seeds did not tolerate desiccation to 10% moisture content, irrespectively of the radicle length. However, when incubated in PEG, those with 1 and 2 mm long radicle attained 71% and 29% survival, respectively. The PEG+ABA treatment was efficient to re-establish DT in seeds with 1 mm long radicles (100% survival). The ultrastructural assays of the cells of germinated seeds with 2 and 5 mm length confirmed the obtained physiological results. Germinated seeds of C. fissilis constitute a useful tool for desiccation tolerance investigations.

Loss of Desiccation Tolerance in Seeds of Tree Species During Germination: Theoretical and Practical Implications

“…Similar results were observed for Glycine max (Senaratna and Mckersie, 1983). These results suggested that the loss of desiccation tolerance at the end of the germination process (radicle protrusion) was a norm, prompting the researches to test desiccation tolerance only in germinated seeds (Masetto et al, 2014(Masetto et al, , 2015Maia et al, 2016). Those studies ignored the possibility that the total loss may occur before Loss of desiccation tolerance in seeds... radicle protrusion, as it was observed in the present study for sucupira, pau-jacaré, and pau-ferro seeds, in which the loss of desiccation tolerance commenced already at the beginning of germination.…”

“…Those studies have been diverse, ranging from physiological and structural characterizations (Reisdorph and Koster, 1999;Guimarães et al, 2011;Pereira et al, 2014) to molecular and ecological analysis (Maia et al, 2011;Costa et al, 2016;Guimarães et al, 2016;Marques et al, 2017). Furthermore, desiccation tolerance reestablishment studies have been carried out to reactivate the mechanisms lost during the germination process (Buitink et al, 2003;Faria et al, 2005;Vieira et al, 2010;Maia et al, 2011;Masetto et al, 2014).…”

Physiological, cellular and molecular aspects of the desiccation tolerance in Anadenanthera colubrina seeds during germination

“…However, recent studies have shown that for seeds from forest species the period of loss of desiccation tolerance is variable. Masetto et al (2014) observed that Sesbania virgata seeds become intolerant to desiccation when protruded radicle reaches 2 mm while Cedrela fissilis did not tolerate desiccation in any radicle length. In studies with Copaifera langsdorffii seeds, Pereira et al (2014) verified that desiccation tolerance loss began at the end of the stage I and it was complete by the middle of stage II of germination.…”

Cell changes during the re-induction of desiccation tolerance in germinated seeds of Sesbania virgata (Cav.) Pers.

“…Findings concerning the loss of desiccation tolerance during the seeds germination have already been reported in germinated seeds of Medicago truncatula (Buitink et al, 2003;Faria et al, 2005), Tabebuia impetiginosa (Vieira et al, 2010) and Cedrela fissilis (Masetto et al, 2014), where DT could be re-established applying a mild osmotic shock with polyethylene glycol. Mature seeds of S. virgata are desiccation tolerant (survive the loss of most of their water content), but they become desiccation sensitive while progressing to germination.…”