Abstract
Recalcitrant seeds are shed at relatively high water contents and are metabolically active, initiating germination without exogenous provision of water. For whole seeds, specialised storage under hydrated conditions at the lowest possible temperatures not having adverse consequences, is required. This study aimed to establish the effect of chilling on the recalcitrant seeds of a single species, Ekebergia capensis, from three different populations occurring in different climates. These were collected from temperate Port Elizabeth (PE; Eastern Cape), sub-tropical St Lucia (KwaZulu-Natal [KZN]) and Tanzania (tropical southern Africa). Viability, axis ultrastructure, solute leakage and protein synthesis were assessed as indicators of response to chilling. These parameters were measured at intervals during storage under hydrated conditions. The seeds from PE retained 80% viability after 12 weeks in storage at 1° and 3 °C and 100% when stored at 6 °C. Those from St Lucia were dead after 38 d in storage at 3 °C, but had retained 100% viability at 6° and 16 °C for the same period. In contrast, all the seeds from Tanzania were dead after 9 d when stored at 3 °C and retained only 10 and 35% viability when stored for 9 d at 6° and 16 °C, respectively. A reduced rate of protein synthesis and increased solute leakage in axes during storage implied a breakdown in metabolic activity. Upon establishing that the PE seeds tolerated slow drying, it is suggested these seeds might be considered to be minimally recalcitrant. Studies of variation in nuclear ribosomal ITS1 sequences revealed the presence of three well-to-strongly-supported monophyletic clades corresponding to the geographical areas from which the seeds were sampled (PE, KZN and Tanzania). Observations indicated that axes from the seeds originating in St Lucia and Tanzania lost ultrastructural integrity when stored at 3 °C. Axes from the PE seeds did not show any deterioration in ultrastructure – for relatively prolonged storage periods. It is clear from the present study, that E. capensis seeds of temperate (PE) origin do tolerate chilling temperatures well, whereas those from sub-tropical St Lucia or the tropical Tanzanian provenance, do not. It is probable that what has been tacitly assumed to be a single species, may not be so.
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Claims 20
Claim · model-written summary
Port Elizabeth seeds retained 80% viability after 12 weeks at 1° and 3 °C.
- Taxon
- Ekebergia capensis
Ekebergia capensise1 - Material
- PEe0
- Treatment
- 1° and 3 °Ce0
- Outcome
- viabilitye0
- Value
- 80%e0
- Qualifier
- after 12 weeks in storagee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The seeds from PE retained 80% viability after 12 weeks in storage at 1° and 3 °C”
e1“Ekebergia capensis”
Claim · model-written summary
Port Elizabeth seeds retained 100% viability after 12 weeks at 6 °C.
- Taxon
- Ekebergia capensisEkebergia capensise1
- Material
- PEe0
- Treatment
- 6 °Ce0
- Outcome
- viabilitye0
- Value
- 100%e0
- Qualifier
- after 12 weeks in storagee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The seeds from PE retained 80% viability after 12 weeks in storage at 1° and 3 °C and 100% when stored at 6 °C.”
e1“Ekebergia capensis”
Claim · model-written summary
St Lucia seeds had died after 38 days at 3 °C.
- Taxon
- Ekebergia capensisEkebergia capensise1
- Material
- St Luciae0
- Treatment
- 3 °Ce0
- Outcome
- deade0
- Qualifier
- after 38 d in storagee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Those from St Lucia were dead after 38 d in storage at 3 °C”
e1“Ekebergia capensis”
Claim · model-written summary
St Lucia seeds retained 100% viability after 38 days at 6° and 16 °C.
- Taxon
- Ekebergia capensisEkebergia capensise1
- Material
- St Luciae0
- Treatment
- 6° and 16 °Ce0
- Outcome
- viabilitye0
- Value
- 100%e0
- Qualifier
- for the same periode0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Those from St Lucia were dead after 38 d in storage at 3 °C, but had retained 100% viability at 6° and 16 °C for the same period.”
e1“Ekebergia capensis”
Claim · model-written summary
All Tanzanian seeds had died after nine days at 3 °C.
- Taxon
- Ekebergia capensisEkebergia capensise1
- Material
- Tanzaniae0
- Treatment
- 3 °Ce0
- Outcome
- deade0
- Qualifier
- after 9 de0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“all the seeds from Tanzania were dead after 9 d when stored at 3 °C”
e1“Ekebergia capensis”
Claim · model-written summary
Tanzanian seeds retained 10% viability after nine days at 6°.
- Taxon
- Ekebergia capensisEkebergia capensise2
- Material
- Tanzaniae1
- Treatment
- 6°e0
- Outcome
- viabilitye0
- Value
- 10e0
- Qualifier
- for 9 de0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“retained only 10 and 35% viability when stored for 9 d at 6° and 16 °C, respectively”
e1“seeds from Tanzania”
e2“Ekebergia capensis”
Claim · model-written summary
Tanzanian seeds retained 35% viability after nine days at 16 °C.
- Taxon
- Ekebergia capensisEkebergia capensise2
- Material
- Tanzaniae1
- Treatment
- 16 °Ce0
- Outcome
- viabilitye0
- Value
- 35%e0
- Qualifier
- for 9 de0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“retained only 10 and 35% viability when stored for 9 d at 6° and 16 °C, respectively”
e1“seeds from Tanzania”
e2“Ekebergia capensis”
Claim · model-written summary
Protein synthesis rate decreased in stored seed axes.
- Taxon
- Ekebergia capensisEkebergia capensise1
- Organ / stage
- axese0
- Outcome
- rate of protein synthesise0
- Direction
- reducede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A reduced rate of protein synthesis and increased solute leakage in axes during storage”
e1“Ekebergia capensis”
Claim · model-written summary
Solute leakage increased in stored seed axes.
- Taxon
- Ekebergia capensisEkebergia capensise1
- Organ / stage
- axese0
- Outcome
- solute leakagee0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A reduced rate of protein synthesis and increased solute leakage in axes during storage”
e1“Ekebergia capensis”
Claim · model-written summary
Reduced protein synthesis and greater leakage implied breakdown of metabolic activity during storage.
- Taxon
- Ekebergia capensisEkebergia capensise1
- Outcome
- breakdown in metabolic activitye0
- Qualifier
- reduced rate of protein synthesis and increased solute leakagee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A reduced rate of protein synthesis and increased solute leakage in axes during storage implied a breakdown in metabolic activity.”
e1“Ekebergia capensis”
Claim · model-written summary
Port Elizabeth seeds tolerated slow drying.
- Taxon
- Ekebergia capensisEkebergia capensise1
- Material
- PEe0
- Outcome
- tolerated slow dryinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the PE seeds tolerated slow drying”
e1“Ekebergia capensis”
Claim · model-written summary
Port Elizabeth seeds were suggested to be minimally recalcitrant.
- Taxon
- Ekebergia capensisEkebergia capensise2
- Material
- PEe1
- Outcome
- minimally recalcitrante0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“these seeds might be considered to be minimally recalcitrant”
e1“the PE seeds tolerated slow drying”
e2“Ekebergia capensis”
Claim · model-written summary
ITS1 sequences resolved three supported monophyletic clades corresponding to the sampled regions.
- Taxon
- Ekebergia capensisEkebergia capensise1
- Gene
- nuclear ribosomal ITS1e0
- Outcome
- three well-to-strongly-supported monophyletic cladese0
- Value
- threee0
- Setting
- PE, KZN and Tanzaniae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Studies of variation in nuclear ribosomal ITS1 sequences revealed the presence of three well-to-strongly-supported monophyletic clades corresponding to the geographical areas from which the seeds were sampled (PE, KZN and Tanzania).”
e1“Ekebergia capensis”
Claim · model-written summary
St Lucia seed axes lost ultrastructural integrity at 3 °C.
- Taxon
- Ekebergia capensisEkebergia capensise1
- Material
- St Luciae0
- Treatment
- 3 °Ce0
- Outcome
- ultrastructural integritye0
- Direction
- loste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“axes from the seeds originating in St Lucia and Tanzania lost ultrastructural integrity when stored at 3 °C”
e1“Ekebergia capensis”
Claim · model-written summary
Tanzanian seed axes lost ultrastructural integrity at 3 °C.
- Taxon
- Ekebergia capensisEkebergia capensise1
- Material
- Tanzaniae0
- Treatment
- 3 °Ce0
- Outcome
- ultrastructural integritye0
- Direction
- loste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“axes from the seeds originating in St Lucia and Tanzania lost ultrastructural integrity when stored at 3 °C”
e1“Ekebergia capensis”
Claim · model-written summary
Port Elizabeth seed axes showed no ultrastructural deterioration during relatively prolonged storage.
- Taxon
- Ekebergia capensisEkebergia capensise1
- Material
- PEe0
- Outcome
- deterioration in ultrastructuree0
- Direction
- did not show anye0
- Qualifier
- relatively prolonged storage periodse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Axes from the PE seeds did not show any deterioration in ultrastructure – for relatively prolonged storage periods.”
e1“Ekebergia capensis”
Claim · model-written summary
Temperate Port Elizabeth seeds tolerated chilling temperatures well.
- Taxon
- E. capensisEkebergia capensise0
- Material
- PEe0
- Outcome
- tolerate chilling temperatures welle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“E. capensis seeds of temperate (PE) origin do tolerate chilling temperatures well”
Claim · model-written summary
St Lucia seeds did not tolerate chilling temperatures well.
- Taxon
- E. capensisEkebergia capensise1
- Material
- St Luciae0
- Outcome
- tolerate chilling temperatures welle1
- Direction
- do note0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“whereas those from sub-tropical St Lucia or the tropical Tanzanian provenance, do not”
e1“E. capensis seeds of temperate (PE) origin do tolerate chilling temperatures well”
Claim · model-written summary
Tanzanian seeds did not tolerate chilling temperatures well.
- Taxon
- E. capensisEkebergia capensise1
- Material
- Tanzaniane0
- Outcome
- tolerate chilling temperatures welle1
- Direction
- do note0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“whereas those from sub-tropical St Lucia or the tropical Tanzanian provenance, do not”
e1“E. capensis seeds of temperate (PE) origin do tolerate chilling temperatures well”
Claim · model-written summary
The authors suggested that the sampled seed groups may not all belong to one species.
- Taxon
- Ekebergia capensisEkebergia capensise1
- Outcome
- a single species, may not be soe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“It is probable that what has been tacitly assumed to be a single species, may not be so.”
e1“Ekebergia capensis”