Challenges of in situ conservation of crop wild relatives

Crop wild relatives (CWRs) will gain in importance as changing climates put both traditional and advanced cultivars under increasing stress, leading to a need for plant breeding to produce new varieties able to grow under the new climate regimes. Traditionally, the approach to the conservation of CWRs has been ex situ - the collection and maintenance of seed accessions in national, regional, and international germplasm banks, supplemented by field genebanks for species with recalcitrant seeds. More recently the need to maintain CWRs in their natural habitats (in situ) has been advocated. This is very different from on-farm conservation of traditional land races and is a complex multidisciplinary process. Particular problems that have to be addressed include the adoption of a workable definition of what is a CWR, application of priority-determining mechanisms because of the large number of candidate species of CWRs, assessment of the effectiveness of conservation approaches, the relative costs of in situ and ex situ approaches, integration of CWR in situ conservation into national programmes, and the challenges posed by global change. CWRs may be conserved in both protected and non-protected areas. Presence in the former is no guarantee of their survival and in most cases some degree of management intervention is required. Experience derived from recent EU- and GEF-funded CWR conservation initiatives will be drawn upon.

Influence of molecular composition on the development of microstructure from sheared polyethylene melts: Molecular and lamellar templating

A combination of in situ and ex situ X-ray scattering techniques and transmission electron microscopy has been used to study the crystallization behaviour of polyethylene, following the imposition of melt shear. In the case of a branched material, the imposition of shear flow up to a rate of 30 s(-1) was found to induce no anisotropy. Although shearing the linear material only ever induced a very small degree of anisotropy in the melt, for shear rates > 0.15 s(-1), subsequent crystallization resulted in increasing anisotropy. Blends of the above two polyethylenes were produced, in which the linear material constituted the minority fraction (similar to 10%). Isothermal crystallization at temperatures where extensive crystallization of the branched material does not occur demonstrated that the behaviour of the linear component of the sheared blend mirrored that of the linear polyethylene alone. However, in addition, it was found that when crystallized in the presence of an oriented morphology, the branched polymer also formed anisotropic structures. We have termed the process templating, in which the crystallization behaviour of the bulk of the system (similar to 90% branched material) is completely altered (spherulitic to oriented lamellar) by mapping it onto a pre-existing minority structure (similar to 10% linear polymer). (c) 2006 Elsevier Ltd. All rights reserved.

Seed survival in Chilean Nothofagus in response to desiccation and storage

Nothofagus alpina, N. obliqua, N. glauca, N. leonii, N. dombeyi and N. pumilio seeds exhibited consistent, albeit slight, sensitivity to extreme desiccation, but nevertheless maintained viability at low moisture contents and cool temperatures (-10 degrees to -20 degrees C) over 2 years. Nothofagus alpina, N. obliqua, N. glauca, N. leonii and N. dombeyi conformed to the seed viability equation of Ellis and Roberts; sensitivity of longevity to temperature was quantitatively similar to that of crop seeds, sensitivity to moisture was somewhat less, and a low-moisture-content limit to the equation was detected at 4.8% moisture content in hermetic storage at 65 degrees C, and possibly similar moisture contents at 30-40 degrees C. These five species show orthodox seed storage behaviour. Therefore, ex-situ conservation of these Nothofagus species in seed banks is possible, but the quality of seed lots collected requires attention. Seed storage behaviour was not defined in N. pumilio: initial seed quality was poor and loss of viability was detected over 2 years at 0 degrees, -10 degrees and -20 degrees C at 2.7% moisture content, but not at 5.2%. The results confirm that the economy of nature in seed storage physiology extends to forest tree seeds, but the repeated observation of reduced sensitivity of longevity to moisture in forest tree seeds requires further investigation.

Drying method influences the development of germinability, dessication tolerance and subsequent longevity of immature seeds of sumauma (Ceiba pentandra (L.) Gaertn. [Bombacaceae])

The ability to germinate, tolerate desiccation and survive in air-dry storage was investigated during early seed development in planta and subsequent ex planta maturation of sumauma (Ceiba pentandra). Immature fruits were collected on three different dates (i.e. from about 5 days before until 7 days after mass maturity). Immature fresh seeds were not able to germinate. Fruits or seeds were subjected immediately after each collection to three different drying treatments with progressively slower rates of dessication: (i) seeds were extracted from the fruits and dried immediately; (ii) fruits were dried in a thin layer; (iii) fruits were dried in a tied polyethylene bag (with 10 holes of 1cm diameter). Drying was in a room maintained at 25 degrees C +/- 3 degrees C and 65%+/- 5% r.h. For treatment (i) the seeds were dried for 6 days in order to reduce moisture content to around 13% ( +/- 2%) moisture content. For treatments (ii) and (iii) the fruits were subjected to different periods of drying depending upon collection date. The results of these post-collection treatments showed generally that the more immature the seeds the slower the rate of drying that is required to improve ability to germinate, ability to tolerate desiccation and potential longevity, but at the third harvest, 7 days after mass maturity, the intermediate drying rate treatment was the most beneficial. Thus post fruit collection treatments can be modified depending upon the stage of seed development in order to provide good to high quality seeds of sumauma when collection has to be made at a site with difficult access at less than ideal times. The results are relevant to seed collection practices for both forestry and ex situ plant biodiversity conservation.

Successful long-term ultra dry storage of seed of 15 species of Brassicaceae in a genebank: variation in ability to germinate over 40 years and dormancy

Seed of 15 species of Brassicaceae were stored hermetically in a genebank (at -5 degrees C to -10 degrees C with c. 3% moisture content) for 40 years. Samples were withdrawn at intervals for germination tests. Many accessions showed an increase in ability to germinate over this period. due to loss in dormancy. Nevertheless, some dormancy remained after 40 years' storage and was broken by pre-applied gibberellic acid. The poorest seed survival occurred in Hormatophylla spinosa. Even in this accession the ability to germinate declined by only 7% between 1966 and 2006. Comparison of seeds from 1966 stored for 40 years with those collected anew in 2006 from the original sampling sites, where possible, showed few differences, other than a tendency (7 of 9 accessions) for the latter to show greater dormancy. These results for hermetic storage at sub-zero temperatures and low moisture contents confirm that long-term seed storage can provide a successful technology for ex situ plant biodiversity conservation.

The development of organized structures in polyethylene crystallized from a sheared melt, analyzed by WAXS and TEM

The development of global orientation and morphological features in linear polyethylene crystallizing from a sheared melt are studied using in-situ time-resolving wide angle X-ray scattering (WAXS) and ex-situ transmission electron microscopy. It is found that samples subjected to a shear rate above a critical value of ~1s-1 result in macroscopically oriented structures in the crystallized sample. This critical shear rate appears to be independent of the differences in molecular weight distribution of the samples studied although the morphologies which develop are sensitive to quite small differences in molecular weight distributions. The presence of shish kebabs in the morphology is shown to differ markedly according to variations in the upper molecular weight fraction of the molecular weight distribution, even though the resulting global orientation does not. The WAXS also reveals that areas which evidence no row nucleated structures still realize high degrees of molecular orientation. It is proposed that the formation of shish kebab or lamellar morphologies in these samples is dependent on the critical density of contiguous elongated crystallization nuclei rather than any specific global criteria.

The effectiveness of botanic garden collections in supporting plant conservation: a European case study

Europe has the greatest concentration of botanic gardens in the world, they cultivate extensive collections of plants that include samples of European threatened plant species. This study looks at the effectiveness of these collections in supporting species conservation. A three part study is presented: (1) the results of a survey and assessment of threatened plants in botanic gardens, as defined by the Bern Convention; (2) case studies illustrating current issues in the ex situ management of European threatened plant species; and (3) presentation of policy recommendations on further improving botanic garden contributions to European plant conservation. The survey indicated that of 119 European botanic gardens in 29 European countries, 105 are cultivating 308 of the 573 threatened plant species listed by the Bern Convention. The survey identified 25 botanic gardens in 14 countries undertaking 51 conservation projects focused on 27 Bern listed species. In particular this survey has established that the majority of taxa are held in a small number of collections, dominated by non-wild origin accessions, and are not adequately documented. The majority of specimens in botanic gardens are cultivated out of the range country and not contributing to a specific conservation project. We review the genetic representation and documentation of origin in collections. Existing plant collections contain representatives of populations, now lost in the wild and maintain samples of at least nine European plant taxa identified as 'Extinct in the Wild'. However, inadequate standards of record keeping has compromised the conservation value of many collections. We highlight the dangers of hybridisation and disease in ex situ collections. The results suggest that botanic garden collections are skewed towards horticulturally robust and ornamental species and do not fully reflect priorities as defined by the Bern Convention. Recognising the limitations of traditional botanic garden collections we propose that botanic gardens more effectively utilise their two core competencies, namely scientific horticulture and public display and interpretation. The unique horticultural skills resident in European botanic gardens could be more effectively utilised through the application of horticulture to the management of wild populations.

Cryopreservation of cocoa (Theobroma cacao L.) somatic embryos by vitrification

Losses of cultivated cocoa (Theobroma cacao L.) due to diseases and continued depletion of forests that harbour the wild progenitors of the crop make ex situ conservation of cocoa germplasm of paramount importance. In order to enhance security of in situ germplasm collections, 2-3 mm floral-derived secondary somatic embryos were cryopreserved by vitrification. This work demonstrates the most uncomplicated clonal cocoa cryopreservation. Optimal post-cryostorage survival (74.5%) was achieved by 5 d preculture of SSEs on 0.5 M sucrose medium followed by 60 min dehydration in cold PVS2. To minimise free radical related cryo-injury, cation sources were removed from the embryo development solution and/or the recovery medium, the former treatment resulting in a significant benefit. After optimisation with cocoa genotype AMAZ 15, the same protocol was effective across all five additional cocoa genotypes tested. For the multiplication of clones, embryos regenerated following cryopreservation were used as explant sources, and vitrification was found to maintain their embryogenic potential.

A decision framework for considering climate change adaptation in biodiversity conservation planning

General principles of climate change adaptation for biodiversity have been formulated, but do not help prioritize actions. This is inhibiting their integration into conservation planning. We address this need with a decision framework that identifies and prioritizes actions to increase the adaptive capacity of species. The framework classifies species according to their current distribution and projected future climate space, as a basis for selecting appropriate decision trees. Decisions rely primarily on expert opinion, with additional information from quantitative models, where data are available. The framework considers in-situ management, followed by interventions at the landscape scale and finally translocation or ex-situ conservation. Synthesis and applications: From eight case studies, the key interventions identified for integrating climate change adaptation into conservation planning were local management and expansion of sites. We anticipate that, in combination with consideration of socio-economic and local factors, the decision framework will be a useful tool for conservation and natural resource managers to integrate adaptation measures into conservation plans.