1. Priority science for the preservation of priority crops
Hugh W. Pritchard
Royal Botanic Gardens, Kew, UK

2. Outline Annex I, ITPGRFA 64 crops or crop complexes
76 genera (Agropyron, Lathyrus, Solanum)
Review preservation options
How many species produce orthodox seeds?
How long will orthodox seeds survive?
Options for the clonal species?
Introduce cryopreservation.
Suggestions for preservation science R & D on crops

3. Methods Information on c. 200 species.
(2016) 29, 292-7
Methods
Information on c. 200 species.
Notable exceptions: Canavalia ensiformis, Coronilla varia

4. Preservation science - drying
Recalcitrant
Orthodox
Vitellaria paradoxa: Shea butter tree; vulnerable; West Africa
3-7 % MC, preferably -18°C for seed banking

5. Viability constants for orthodox seeds
log σ = KE - CW logm - CHt - CQt 2
Distribution of seed deaths (lifespan)
Sensitivity to moisture level
Sensitivity to temperature
(Ellis & Roberts, 1980; Ann Bot)
Available for 19 species (17 / 76 genera = 22%):
Beta, Brassica, Cicer, Eleusine, Helianthus, Hordeum, Malus, Oryza, Pennisetum, Phaseolus, Phleum, Pisum, Sorghum, Trifolium, Triticum, Vigna, Zea.

6. Seed banks USDA: Fort Collins, USA ICAR: New Delhi, India
CROPS
KIB-CAS: GBOWS
RBG Kew: MSB
WI LD
SP.

7. Seed lifespan of 63 Annex I crops
(Walters et al., 2005)
>10 years at 5°C,
plus c. 25 years at -18°C
Number of species
Agrostis tenuis (232)
Lens culinaris (365)
Vigna radiata (457)
Lifespan (P50 estimate, years)

8. Seed lifespan: 276 crop (global, local) Storage: >10 years at 5° C,
22 %
53 %
Storage: >10 years at 5° C,
plus c. 25 years at -18°C
26 % collections (46 families) with significant drop in wild species seed viability during 20 years storage under Kew bank conditions. (Probert et al., 2009; Ann Bot)
Walters et al., SSR 2005;
Li, Pritchard, TIPS 2009

9. Increasing seed lifespan
22 %
53 %
OPTIONS?
Li, Pritchard, TIPS (2009)

10. Option: ultra-dry seeds
7 species in Brassicaceae (Mira et al., 2015)
E. vesicaria
B. repanda
M. arvensis
R. nasturtium-aquaticum
S. runcinatum
M. littorea
Longevity P50 (days)
S. alba
Water content (g/g)

11. Option: ultra-cool seeds
Lifespan improved compared with -18C:
Lactuca sativa (Walters et al., 2004)
Gavilea littoralis (Seaton et al., 2013)
Allium cepa (Chaudhury pers comm.)

12. Dry seeds – priority science
Better prediction of lifespan.
Research to maximise lifespan:
Reducing humidity;
Reducing temperature;
Reducing oxygen tension.
Development of standards:
Standardisation of containers;
Review standards for regeneration, germination, etc.

13. Preservation science - cooling
MC (% FW)
Decreasing lifespan
Risk of ice
formation
The glassy state
Williams and Leopold (1989) – maize embryos
Cryopreservation

14. Cryopreservation of tissues
Annex I species
Method
Success
Breadfruit
Axis vitrification
50 % into plants
Citrus
>17 sp, partial dry embryo
Many years
Coconut
Embryos + ED shoot tip
Phenotype OK
Aroids
DV shoot tip
>73% regen.
Yams
52% developing
Sw. Potato
24 acc, DV shoot tips
2-66% shoot form.
Apple
37 acc, winter buds
Ave. 69% recovery
Cassava
79% recovery
Banana
56 acc, DV shoot tip
Ave. 53% regen.
Potato
1028 acc, DV shoot tip
34-59% recovery
PVS2:
30% glycerol,
15% DMSO,
15% ethylene glycol in MS medium m sucrose
ED = encapsulation-dehydration; DV = droplet vitrification

15. Summary
Preservation information available for c. 200 species from the 64 crops / complexes;
Many successes (seed storage and large-scale cryo application);
Some challenges to improve lifespan of the orthodox seeds and cryo of shoot tips of some tropical clonal species and embryos of recalcitrant seeds.

16. Cryobiotechnology ‘hotspots’
Need to strengthen national facilities to be > critical mass

17. Acknowledgements: