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The Solanaceae Germplasm Bank at the Botanical Garden of Nijmegen

Gerard W.M. Barendse and Gerard M. van der Weerden
TheNijmegen Botanical Garden

The Netherlands


Home | Contents | Abstract | Introduction | Ex-situ Conservasion | The Solanaceae Germplasm Bank | The Living Plant Collection | Accessibility and documentation: building a Solanaceae Information Network | References & Legends



Abstract

The Solanaceae family has yielded economic important food plants (potato, tomato, chilli peppers, eggplant), plants as a source of drugs in medicine (belladonna, henbane, mandrake, thorn-apple), plants with stimulants (tobacco), omamentals (Browallia, Brugmansia, Cestrum, Nicotiana, Nierembergia, Petunia, Salpiglossis) while some species are extensively used in biotechnological and molecular research (tobacco, tomato, potato, petunia). Therefore, the conservation of Solanacea genetic resources is of great importance. The Botanical Garden of N4megen has built a germplasm collection of non-tuberbearing Solanaceae consisting of about 1800 accessions which represent 50 genera and approximately 550 species and subspecies of the Solanaceae.

A major objective of our Botanical Garden is to create a Solanaceae Information Network database which collates our accessions with the dispersed taxonomic as well as other relevant information on Solanaceae in the literature.

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Introduction

The family Solanaceae is of great economic importance and is one of the larger flowering plant families with some 2000 species. On the one hand the Solanaceae family has yielded important food plants (potato, tomato, chilli peppers, eggplant) of which the potato (Solanum tuberosum and related species) is the most important food crop afier respectively rice, wheat and maize (Hawkes, 1990, 1991) and also ornamental plants (Browallia, Brugmansia, Cesfrum, Lycium, Nicandra, Nicotiana, Nierembergia, Petunia, Physails, Salpiglossis, Schizanthus). On the other hand the Solanaceae family is well-known for plants as a source of medicinal drugs, stimulants and poisons (Roddick, 1991), e.g. belladonna (Atropa belladonna), henbane (Hyos cyamus niger), mandrake (Mandragora officinarum), thornapple (Datura species), whitania somn4&ra and tobacco (Nicotiana tabacum and Nicotiana rustkum). Finally, certain solanae ceous plants like the tobacco, tomato, potato and petunia have been and are still extensively used for biotechnological and molecular research.

The Solanaceae germplasm collection of the Botanical Garden of Njjmegen was initiated more than 30 years ago. Especially in the last decade our germplasm collection of Solanaceae has been reorganised and considerably expanded. This has resulted in probably the most extensive germplasm collection of non-tuberbearing Solanaceae in the world (Barendse and Van der Weerden, 1996, 1997). Our Solanaceae gene bank constitutes an excellent complement to the Center of Genetic Resources, Wageningen, the Netherlands, which harbours the tuberbearing Solanaceae species as well as landraces and cultivars of non-tuberous Solanaceae. Together with other international institutes, especially the University of Birmingham, our garden has participated in the EU flinded project to develop a European Solanaceae Information Network (ESIN) database (Mace etai,1998).

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Ex situ Conservation

Ex situ conservation of the genetic resources of Solanaceae is achieved through maintainance of a large living plant collection in connection with a seed bank. The living plant collection is especially useflill to maintain perennial, recalcitrant and vegetatively propagated species which ofien produce little or no seed. For some species they are the only available option to maintain germplasm for conservation. An important reason for maintaining a living collection is the production of seed for genebanking, the collection of herbarium material and the ability to study the plants for proper identification and documentation (e.g. photographs). Seedbanking is of course the most cost-effective way in providing genetic resources for the long-term ex situ conservation and is mostly employed by botanic gardens and gene banks (Heywood, 1989; Touchell & Dixon, 1997). However, the value of a seedbank is greatly determined by proper identification and documentation of its accessions.

An important advantage of ex situ conservation is that the genetic resources of Solanaceae from the dispersed habitats are brought together on one or a few location(s) which make them more accessible to comparative taxonomic and other studies as well as to plant breeders.

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The Solanaceae Germplasm Bank
In order to build a valuable germplasm collection of Solanaceae seeds and/or plant material, preferably from known wild origin, are acquired through collection and exchange, raised to seed for genebanking, taxonomically identified, and documented by description, photography and by collecting herbarium material. Over the years the quality of our germplasm bank has been enhanced by taxonomic (re)identification and by replacing many of our accessions with material obtained from known wild origin. In order to enhance the gene pool (biodiversity, cf Swanson, 1996)) and to reduce genetic erosion, whenever possible, several accessions from different wild locations were acquired and maintained.

The need to improve accessibility and hence utilization of the genetic recources is widely recognized and has led to the concept of 'core' collections (Hodgkin, 1991). Our Botanical Garden has built a specialised collection of Solanaceae which approaches this concept of a core collection and which is internationally recognized. A core collection assumes a minimum of repetitiveness which contributes to the development of an integrated conservation approach, ensures the conservation of a significant part of the diversity present in nature and is an indis pensable complement to in situ conservation.

The core collection is also an important basis for research (e.g. molecular taxonomy as well as other studies) by the immediate availability of the same plant material to researchers worldwide. Moreover, plants in cultivation lend themselves to studies which can not be achieved in the dispersed and remote wild populations. An important feature of our collection may be to promote the conservation and use of underutilized and neglected crops (Edmonds & Chweya, 1997). At present our germplasm bank contains about 1800 accessions representing 50 genera and approximately 550 species and subspecies. An overview is presented in Table 1 (After D'Arcy, 1991).

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The Living Plant Collection

Botanic Gardens are uniquely suited to study the cultivation requirements, the reproductive biology and the propagation of individual plants. Our Botanical Garden has excellent green house facilities to grow Solanaceae year-round, outside as well as in greenhouses under different light and temperature regimes. These facilities have proven to be very important for raising plants to seed. A sizable number of our accessions had to be grown for several years and often with supplemental lighting in winter before they would produce seeds. In addition, we have been experimenting with sofl mixtures for optimal plant development, especially for those accessions which had to be grown for several years. At present our substrate consists of a commercial potting soil based on a mixture of coarse peat (60%), Swedish peatmoss (20%), clay (10%) and perlite (10%). All plants are grown in individual containers to accomodate their requirements with regard to watering, fertilizer etc., to prevent disease spread via root contact, and and also to be able to move plants as necessary from warm to cold greenhouse or outside in the summer.

Growing Solanaceae at our latitude has the advantage that there is no danger of escape of known weedy species since they will not survive our winters. At present we have started a program to address plagues in the Solanaceae by biological means which appears to be quite successftil so far. Harvested seeds are cleaned and careftilly dried at room temparuture, put in labelled paper bags which in turn are stored together with sflica gel in freezer boxes at ca 1 0C in a cold room. The germination capacity is checked as deemed necessary, based on experien ce, ranging between one to five years after harvest.

Quite a few of our accessions were derived from seeds collected in the wild many years ago (e.g. by R.N. Lester from Birmingham University, U.K.) and would be very hard to acquire again and include some rare and threatened species. These are now successfiilly grown in our greenhouses to provide seeds for our gene bank.

Finally, the successfbll maintainance and flirther expansion of our Solanaceae germplasm collection is for a large extent enabled by a capable and motivated team of collaborators at our Botanical Garden.

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Accessibility and Documentation: Building a Solanaceae Information Network

Access to genetic resources and their use in any research program depends heavily on the identification, description and other information of the available plant material in the germ plasm bank. In our case all newly acquired accessions receive an unique accession number which together with its accompanying information is entered in our database. As the acquired material is raised to bloom and seed set, further information related to taxonomic identification, photography and collection of herbarium material is added into the database and finally also collated to information extracted from the literature.

Besides the database containing our accessions we have also built an extensive computer based reference system consisting of a bibliography of literature on Solanaceae sensu lato and references to the copies of many of the the taxonomic Solanaceae literature in our possession. A major objective is to create a Solanaceae database, based on and compatible with the ESIN database, which the collates our accessions with the dispersed taxonomic information and all other kinds of research information in the litdrature, and to create a Solanaceae Information Network (Fig. 1) which will be accessible via the Internet, e.g. via our own web page and in the future also via the Agricultural Genome Information System (AGIS), an integrated system for agricultural genome analysis at the National Agricultural Library (>AL), USDA, USA. At present the information on our accessions can be viewed at our WWW page .

In addition, further internationalization of our genebank will be pursuit by expanding our international collaboration with researchers/institutes involved in Solanaceae research at all levels, e.g. taxonomic, molecular, biotechnical, physiological studies etc. as well as crop science. An important step in this direction will be the organisation of the 5th International Solanaceae Conference which will take place in the year 2000, Nijmegen, The Netherlands.

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References

Legends

Table I : Compilation of the Solanaceae: Subfamilies, Tribes and Genera. Total number of species according to D'Arcy (1991) and number of species in the germplasm bank of the Botanical Garden of Nijmegen.

Figure 1: Flow sheet of the creation of a Solanaceae Information Network at the Botanical Garden of Nijmegen.



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