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

Abstract

During germination, orthodox seeds become gradually intolerant to desiccation, and for this reason, they are a good model for recalcitrance studies. In the present work, physiological, biochemical, and ultrastructural aspects of the desiccation tolerance were characterized during the germination process of Anadenanthera colubrina seeds. The seeds were imbibed during zero (control), 2, 8, 12 (no germinated seeds), and 18 hours (germinated seeds with 1 mm protruded radicle); then they were dried for 72 hours, rehydrated and evaluated for survivorship. Along the imbibition, cytometric and ultrastructural analysis were performed, besides the extraction of the heat-stable proteins. Posteriorly to imbibition and drying, the evaluation of ultrastructural damages was performed. Desiccation tolerance was fully lost after root protrusion. There was no increase in 4C DNA content after the loss of desiccation tolerance. Ultrastructural characteristics of cells from 1mm roots resembled those found in the recalcitrant seeds, in both hydrated and dehydrated states. The loss of desiccation tolerance coincided with the reduction of heat-stable proteins.Keywords: desiccation tolerance, forest seeds, drying.Aspectos fisiológicos, celulares e moleculares da tolerância à dessecação em sementes de Anadenanthera colubrina durante a germinação ResumoDurante a germinação, sementes ortodoxas tornam-se gradualmente intolerantes à dessecação, e por isso podem ser utilizadas como modelo para o estudo da recalcitrância. No presente trabalho realizou-se uma caracterização dos aspectos fisiológicos, bioquímicos e ultraestruturais da perda da tolerância à dessecação de sementes de Anadenanthera colubrina em processo germinativo. Para isso as sementes foram embebidas durante 0 (controle), 2,8,12 e aproximadamente 18 horas (sementes germinadas com 1 mm de radícula), secas por 72 horas, reidratadas e a sobrevivência avaliada. Ao longo da embebição foram realizadas análises citométricas, ultraestruturais e extração de proteínas resistentes ao calor e após embebição e secagem foram avaliados danos ultraestruturais. A tolerância à dessecação foi totalmente perdida após a protrusão radicular. Não houve aumento do conteúdo de DNA 4C quando a tolerância à dessecação foi perdida. Características ultraestruturais de células de radículas de 1 mm assemelharam-se às encontradas em sementes recalcitrantes tanto no estado hidratado quanto desidratado. A perda da tolerância à dessecação coincidiu com a redução do conteúdo de proteínas resistentes ao calor.Palavras-chave: tolerância à dessecação, sementes floretais, secagem.

Desiccation Tolerance and germination of Psidium guajava seeds from different regions of Brazil

“…As germination advances, orthodox seeds tend to progressively lose DT, which is usually completely lost after radicle protrusion. This was the case for P. guajava seeds in our study, and likewise for Anadenanthera colubrina, Leucaena leucocephala, Peltophorum dubium, and Senna multijuga in previous studies (Rodrigues-Junior et al, 2015;Castro et al, 2017). The mechanisms involved in desiccation tolerance are gradually deactivated during germination, with a complete loss of tolerance for many species usually coinciding with radicle protrusion (Buitink et al, 2003;Bewley et al, 2013).…”

“…Desiccation tolerance (DT) is commonly described as the ability of organisms and organs, such as seeds, to survive minimum water levels without accumulating lethal damage, while remaining able to recover their normal metabolism after hydration (Leprince and Buitink, 2010;Dekkers et al, 2015). However, throughout their development, the physiological tolerance behavior of orthodox seeds may change as germination advances at different water availability conditions (Bewley et al, 2013;Pereira et al, 2014;Rodrigues-Junior et al, 2015;Castro et al, 2017). In most species that produce orthodox seeds, DT loss is related to radicle protrusion (Buitink et al, 2003;Bewley et al, 2013).…”

Impact of fast and slow desiccation on Garcinia imberti seed and seedling vigour

“…Most species of the genus Garcinia also shed their seeds at high moisture contents with low viability and desiccation sensitivity (10) and are thus considered to be recalcitrant. Recalcitrant seeds lose viability at relatively high moisture contents and their desiccation sensitivity imposes a severe problem for the long term conservation of many tropical plants' genetic resources (11,12). Consequently the main challenge for the ex situ conservation of G. imberti is its sensitivity to drying of the seeds below a critical moisture content.…”

Dehydration tolerance and storage sensitivity of Campomanesia adamantium seeds

“…Consequently, seeds with high moisture levels at maturation can only be stored for short periods under conditions that prevent dehydration. The length of hydrated storage is limited by the germination that may occur without additional water and the seed-related fungi that proliferate in this moist environment (Berjak et al 2013;Castro et al 2017).…”