Physiology of Desiccation-Sensitive (Recalcitrant) Seeds and the Implications for Cryopreservation

Pammenter, N. W.; Berjak, Patricia

doi:10.1086/673302

Cited by 72 publications

(61 citation statements)

References 43 publications

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“…Such damage harms the membrane, protein and DNA system by forming free radicals and toxic byproducts. Finally, after a storage time at high temperatures, there may be damage by macromolecular denaturation with formation of many dilated vacuoles (Pammenter and Berjak, 2000;Umarani et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Exploratory studies for cryopreservation of Coffea arabica L. seeds

et al. 2017

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-Cryopreservation is a viable option for conservation of coffee germplasm. However, for this technique to be completely successful, it is of fundamental importance to carry out studies that ensure maintenance of cell integrity before and after immersion in liquid nitrogen (LN). Therefore, the aim in this study was to investigate the water content, cooling rate, and final temperature most suitable for cryopreservation of Coffea arabica L. seeds. The seeds were dried by silica gel to water contents of 5, 10, 15, 20, 30 and 40 % wb, subjected to slow cooling treatments at speeds of -1, -3 and -5 °C min.-1 to final temperatures of -40, -50 and -60 °C and then directly immersed in LN. After storage, seeds were rewarmed at 40 °C for two minutes. The survival rate and viability of the seeds and embryos were evaluated by the tetrazolium and germination tests.Results of the tetrazolium test indicate that embryos excised from cryopreserved seeds are less sensitive to cryopreservation than whole seeds are. The water content of 20% wb and the use of zygotic embryos led to the highest survival rate of the coffee seeds, depending on the cooling rate and the final temperature of precooling.Index terms: silica gel, water content, slow cooling, liquid nitrogen, coffee.Estudos exploratórios para a criopreservação de sementes de Coffea arabica L.RESUMO -A criopreservação é uma opção viável para a conservação de germoplasma de café. Entretanto, para que essa técnica apresente total sucesso é de fundamental importância realizar pesquisas que garantam a manutenção da integridade celular antes e após a imersão em NL. Portanto, o objetivo neste estudo foi investigar o teor de água, velocidade e temperatura final de resfriamento mais adequados para criopreservar sementes de Coffea arabica L. As sementes foram secadas em sílica gel até teores de água de 5, 10, 15, 20, 30 e 40% bu, submetidas a tratamentos de resfriamento lento nas velocidades -1, -3 e -5 ºC min -1 até às temperaturas finais de -40, -50 e -60 ºC e diretamente imersas em NL. Após armazenamento as sementes foram reaquecidas por dois minutos à 40 ºC. A sobrevivência e a viabilidade de sementes e embriões foram avaliadas por meio do teste de tetrazólio e de germinação. Por meio do teste de tetrazólio, observa-se que embriões excisados das sementes criopreservadas são menos sensíveis à criopreservação quando comparados às sementes inteiras. O teor de água de 20% bu permite maior sobrevivência das sementes de Coffea arabica L., bem como de embriões zigóticos após a criopreservação, dependendo das velocidades e temperaturas finais de pré-resfriamento.Termos para indexação: sílica gel, teor de água, resfriamento lento, nitrogênio líquido, café.

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Section: Introductionmentioning

confidence: 99%

Exploratory studies for cryopreservation of Coffea arabica L. seeds

et al. 2017

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“…Studies on the metabolism of recalcitrant seeds have been performed by several authors (Barbedo & Bilia 1998;Song et al 2003;Berjak & Pammenter 2008;Caccere et al 2013;Pammenter & Berjak 2014;Walters 2015), including studies on ex situ conservation by storage (Pammenter et al 1994;Drew et al 2000;Li & Pritchard 2009;Pasquini et al 2012;Charloq et al 2013;Walters et al 2013;Bonjovani & Barbedo 2014;Liu et al 2014). Storage of recalcitrant seeds under desiccating conditions resulted in the initiation of subcellular damage, which may be repaired when seeds are set-out to germinate (Farrant et al 1989;Tarquis & Bradford 1992).…”

Section: Introductionmentioning

confidence: 99%

Establishment of post-harvest early-developmental categories for viability maintenance of Araucaria angustifolia seeds

Araldi

Coelho

2015

Acta Bot. Bras.

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Araucaria angustifolia seeds are recalcitrant, and their metabolism remains high during storage. This research aimed to describe the initiation of germination in A. angustifolia seeds during storage in order to standardize the assessment of physiological quality and to promote seed conservation. Seeds were collected from two populations and stored for 270 days in the natural laboratory environment and cold chamber. Seeds were classified according to four early developmental stages: I -mature seeds; II -seeds with elongation along the embryonic axis; III -beginning of root protrusion; IV -advanced germination stage, with seedling shoots. After categorization, physical and physiological quality was assessed. In freshly collected seeds, only category I was observed. At 270 days, approximately 40% of seeds were in category III in laboratory conditions, while the maintenance in a cold chamber delayed germinative metabolism. Viability tests showed that seeds in categories III and IV were more susceptible to damage caused by storage.In conclusion, the percentage of viable A. angustifolia seeds depends on the development stage after collection. Seeds that have reached early developmental category III should be prioritized for propagation, while those remaining in categories I and II should be longer stored with periodic assessment for reduction in physiological quality.

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“…The challenge of exposing seeds to below-zero temperatures is freezing the seed without the formation of ice crystals in the intracellular medium, which causes rupture of the cell membrane system, resulting in loss of semi-permeability and of compartmentalization of cell structures (Pammenter;Berjak, 2014). The formation of ice crystals in the cells occurs if the water content in the plant tissues is high.…”

Section: Introductionmentioning

confidence: 99%

“…The effects of water content and temperature are interdependent, and critical water content always increases as temperature decreases (Dussert et al, 2003;Dussert;Engelmann, 2006). Pammenter and Berjak (2014) report that removal of water from the seed can cause physical damage to tissues, disordering metabolism and consequently affecting seed germination capacity.…”

Section: Introductionmentioning

confidence: 99%

Tolerance of Coffea arabica L. seeds to sub zero temperatures

et al. 2017

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Preservation of the quality of coffee seeds is hindered by their intermediate behavior in storage. However, long-term storage at sub zero temperatures may be achieved by adjusting the water content of the seeds. The aim of this study was to evaluate the tolerance of coffee seeds to freezing, in relation to physiological and enzymatic modifications. Coffee seeds were dried in two manners, rapid and slow, to water contents of interest, 0.67, 0.43, 0.25, 0.18, 0.11, and 0.05 g H 2 O g -¹ dw (dry basis). After drying, the seeds were stored at a temperature of -20 ºC and of 86 ºC for 24 hours and for 12 months, and then compared to seeds in cold storage at 10 ºC. The seeds were evaluated through calculation of percentage of normal seedlings, percentage of seedlings with expanded cotyledonary leaves, dry matter of roots and of hypocotyls, and viability of embryos in the tetrazolium test. Expression of the enzymes superoxide dismutase, catalase, and peroxidase were evaluated by means of electrophoretic analysis. Only seeds dried more slowly to 0.18 g H 2 O g -1 dw present relative tolerance to storing at -20 °C for 12 months. Coffee seeds do not tolerate storage at a temperature of -86 ºC for 12 months. Water contents below 0.11g H 2 O g -¹ dw and above 0.43 g H 2 O g -¹ dw hurt the physiological quality of coffee seeds, regardless of the type of drying, temperature, and storage period. Coffee seed embryos are more tolerant to desiccation and to freezing compared to whole seeds, especially when the seeds are dried to 0.05 g H 2 O g -¹ dw. The catalase enzyme can be used as a biochemical marker to study tolerance to freezing in coffee seeds.Index terms: Drying; silica gel; saturated saline solutions; freezing; antioxidant enzymes. RESUMOA preservação da qualidade de sementes de café é dificultada pelo comportamento intermediário no armazenamento. Porém, a conservação a longo prazo em temperaturas subzero pode ser conseguido com o ajuste do teor de água das sementes. Objetivou-se neste trabalho avaliar a tolerância de sementes de café ao congelamento, com relação às modificações fisiológicas e enzimáticas. As sementes foram submetidas a dois tipos de secagem, rápida e lenta, até os teores de água de interesse, de 0,67, 0,43, 0,25, 0,18, 0,11, 0,05 g H 2 O g -¹ dw (base seca). Após secagem, as sementes foram armazenadas em temperatura de -20 e de -86 ºC, por 24 horas e por 12 meses, sendo comparadas às sementes armazenadas em câmara fria a 10 ºC. As sementes foram avaliadas pela porcentagem de plântulas normais, plântulas com folhas cotiledonares expandidas, matéria seca de raízes e de hipocótilos e viabilidade dos embriões no teste de tetrazólio. A expressão das enzimas superóxido dismutase, catalase e peroxidase foi avaliada por meio de análise eletroforética. Apenas as sementes secadas lentamente até 0,18 g H 2 O g -¹ dw apresentam relativa tolerância ao armazenamento a -20 °C por 12 meses. Sementes de café não toleram o armazenamento à temperatura de -86 ºC por 12 meses. Umidades abaixo de 0,11g H 2 O g -¹ dw ...

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Physiology of Desiccation-Sensitive (Recalcitrant) Seeds and the Implications for Cryopreservation

Cited by 72 publications

References 43 publications

Exploratory studies for cryopreservation of Coffea arabica L. seeds

Exploratory studies for cryopreservation of Coffea arabica L. seeds

Establishment of post-harvest early-developmental categories for viability maintenance of Araucaria angustifolia seeds

Tolerance of Coffea arabica L. seeds to sub zero temperatures

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