Loss of desiccation tolerance in Copaifera langsdorffii Desf. seeds during germination

Abstract

This study evaluated the loss of desiccation tolerance in C. langsdorffii seeds during the germination process. Seeds were imbibed for 24, 48, 72, 96, 120 and 144 hours and dried to the initial moisture content, kept in this state for 3 days after which they were submitted to pre-humidification and rehydration. Ultraestructural evaluations were done aiming to observe the cell damage caused by the dry process. Desiccation tolerance was evaluated in terms of the percentage of normal seedlings. Seeds not submitted to the drying process presented 61% of normal seedlings, and after 24 hours of imbibition, followed by drying, the seeds presented the same percentage of survival. However, after 48 hours of imbibition, seeds started to lose the desiccation tolerance. There was twenty six percent of normal seedlings formed from seeds imbibed for 96 hours and later dried and rehydrated. Only 5% of seeds imbibed for 144 hours, dried and rehydrated formed normal seedlings. At 144 hours of imbibition followed the dry process, there was damage into the cell structure, indicating that the seeds were unable to keep the cell structure during the drying process. Copaifera langsdorffii seeds loses the desiccation tolerance at the start of Phase 2 of imbibition.Keywords: Copaíba, desiccation sensitivity, imbibition. Perda da tolerância à dessecação em sementes deCopaifera langsdorffii durante a germinação ResumoEste estudo avaliou a perda da tolerância à dessecação em sementes de C. langsdorffii durante o processo germinativo. Sementes foram embebidas por 24, 48, 72, 96, 120 e 144 horas e depois secas até a umidade inicial, sendo mantidas neste estado durante 3 dias, quando então foram submetidas a pré-umidificação e reidratação. Avaliações ultraestruturais foram realizadas objetivando observar danos nas células causados pelo processo de secagem. A tolerância à dessecação foi avaliada pelo percentual de plântulas normais. Sementes não submetidas ao processo de secagem apresentaram 61% de plântulas normais, sendo que após 24 horas de embebição seguida de secagem, houve o mesmo percentual de sobrevivência. Contudo, após 48 horas de embebição, as sementes começaram a perder a tolerância à dessecação. Vinte e seis por cento de sementes formaram plântulas normais após embeberem por 96 horas e secas. Apenas 5% de sementes embebidas por 144 horas e secas formaram plântulas normais. Após 144 horas de embebição, seguida de secagem, verificou-se danos na estrutura celular, o que indica que as sementes não são capazes de manter a estrutura celular durante o processo de secagem. Verificou-se no presente estudo que sementes de C. langsdorffii perdem a tolerância à dessecação no inicio da fase 2 da embebição.Palavras-chave: Copaíba, sensibilidade à dessecação, embebição.

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

“…The membrane shift accompanied by cell death have been broadly reported in the literature. Pereira et al (2014) also observed cell collapse and plasmatic membrane shift in Copaifera langsdorffii seeds imbibed by 144 hours e dehydrated.…”

“…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.…”

Desiccation tolerance and longevity of germinated Sesbania virgata (Cav.) Pers.seeds

“…The point during germination when DT is lost varies among species. For example, within legume species, Copaifera langsdorfii and Pisum sativum lose DT before radicle protrusion (Pereira et al, 2014;Reisdorph and Koster, 1999), while Glycine max, Medicago truncatula and Peltophorum dubium lose DT after radicle protrusion (Buitink et al, 2003;Guimarães et al, 2011;Senaratna and McKersie, 1983). Here it is shown that S. virgata (also a legume) seeds lose DT progressively after radicle protrusion (Figure 2), being almost completely sensitive when the protruded radicle length reaches 5 mm.…”

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

“…Germinating orthodox seeds have been used in studies on the loss of desiccation tolerance to understand the mechanisms linked to desiccation tolerance (Reisdorph and Koster, 1999;Daws et al, 2007;Pereira et al, 2014;Maia et al, 2016). 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).…”

“…However, in some species that produce orthodox seeds, such as Senna multijuga, Cecropia longipes, Luehea seemannii, and Ochroma pyramidale, drying of the seeds before the conclusion of the germination process resulted in seed death (Daws et al, 2007;Rodrigues-Junior et al, 2014). Drying of the seeds at imbibition phase 1 is lethal in Copaifera langsdorffii (Pereira et al, 2014) and neotropical seed species (Daws et al, 2007).…”