About 98,000 pea accessions are preserved worldwide. The total germplasm col- lection is much smaller owing to substantial overlap (on an average 20%, but some particularly smaller collections are duplicates up to 90%). There are 25 larger collec- tions preserving pea diversity, holding together around 72,000 accessions. The remain- ing 27,000 accessions are distributed over 146 collections worldwide. As shown in
Table 3.1, only 1876 (2%) of these are wild pea relatives, approximately one-quarter (24,000) each are commercial varieties, 8500 landraces, while 600 and 6000 repre- sent breeding and recombinant inbred lines or mutant stocks, respectively (Figure 3.1). In the case of true wild Pisum species, there are only 706 P. fulvum, 624 P. subsp.
elatius, 1562 P. sativum subsp. sativum (syn. P. humile/syriacum) and 540 P. abys-
sinicum accessions (Figure 3.1) preserved ex situ in collections. Moreover, when passport data on geographical origin are summarized, there is a large bias (17%) towards Western and Central European accessions, as these regions represent mod- ern pea breeding activities. Substantially less well represented are Mediterranean (2.5%), Balkan (2%) regions, Caucasus (0.8%) and Central Asia (2%) centres of pea crop domestication and diversity (Table 3.1; Figure 3.2), where higher variation can be anticipated. Currently, no international centre conducts pea breeding, since International Center for Agricultural Research in the Dry Areas (ICARDA) in Syria relinquished the international mandate for genetic conservation of peas, and world- wide no single collection predominates in size and diversity (Table 3.1). Important genetic diversity collections of Pisum with over 1000 accessions are found in national gene banks of at least 15 countries (Table 3.1), with many other smaller collections worldwide (Smýkal, Coyne, et al., 2008; Smýkal et al., 2012). A high level of dupli- cation (an estimated 20% on average) exists between the collections, thus reduc- ing the actual level of diversity. In spite of this overlap, each represents a unique assembly. These are dominated by cultivated forms (Table 3.1; Figure 3.1), and although wild forms in these collections are highly diverse, they are comparably few and inadequately sampled (Ellis, 2011; Smýkal et al., 2011). The much smaller col- lections of wild relatives of pea are less widely distributed and there is more clarity when tracing these accessions to their origin, although precise collection sites are often unknown. Furthermore allelic diversity in wild material is unknown. There are still important gaps in the ex situ collections, particularly of wild and locally adapted materials, which need to be addressed before these genetic resources are lost forever
Code Country Institute Number of Accessions
Web Site Online Catalogue
Genotyped Phenotyped Core
VIR Russia N.I. Vavilov Research Institute of Plant Industry, St. Petersburg
6790 http://www.vir.nw.ru No No No
USDA USA Plant Germplasm
Introduction and Testing Research Station, Pullman
6827 http://www.ars-grin.gov Yes Partly Yes Formed
BAR Italy CNR-Istituto Di Genetica Vegetale, Bari
4558 http://www.igv.cnr.it Yes No No
SAD Bulgaria Institute of Plant
Introduction and Genetic Resources, Sadovo
2100 http://www.genebank.
hit.bg
No No Partly
NGB Sweden NordGen, Nordic Genetic Resource Centre, Alnarp
2849 http://www.nordgen.org/
sesto
Yes Partly Partly CGN The
Netherlands
Centre for Genetic Resources, Wageningen
1002 http://www.cgn.wur.nl/pgr/ Yes No No
ATFC Australia Australian Temperate Field Crop Collection, Horsham
7432 http://www2.dpi.qld.gov.
au
No Yes Yes Formed ICARDA Syria International Center for
Agricultural Research in the Dry Areas
6105 http://www.icarda.cgiar. org
No No No
GAT Germany Leibniz Institute of Plant Genetics and Crop Plant Research
5343 http://www.ipk-
gatersleben.de
Yes No Yes
ICAR China Institute of Crop Sciences, CAAS China
Code Country Institute Number of Accessions
Web Site Online Catalogue
Genotyped Phenotyped Core
JIC UK John Innes Centre, Norwich 3567 http://www.jic.ac.uk Yes Yes Yes Formed WTD Poland Plant Breeding and
Acclimatization Institute Blonie, Radzikow
2896 http://www.igr.poznan.pl Yes No No
INRA France INRA CRG Légumineuse à grosses graines, Dijon
8839 http://195.220.91.17/
legumbase
Yes Partly Yes Formed INIA Spain Instituto Nacional
de Investigación y Tecnología Agraria
1648 http://www.inia.es Yes Partly Partly
ITACyL Spain Instituto Tecnológico Agrario de Castilla y León
1772 http://www.itacyl.es No Partly Partly Formed
UKR Ukraine Yurjev Institute of Plant Breeding, Kharkov
1671 http://www.bionet.nsc.ru No No No
CZE Czech AGRITEC, Research, Breeding and Services Ltd., Sumperk
1326 http://genbank.vurv.cz Yes Yes Yes Formed
CZE Czech Centre for Research of Vegetables and Special Crops, Olomouc
1414 http://genbank.vurv.cz/ genetic/resources
Yes No Yes
HUN Hungary Research Centre for Agrobiodiversity, Tápiószele
1205 http://www.rcat.hu No No No
CAN Canada Plant Gene Resources of Canada, Saskatchewan, Canada
616 http://www.agr.gc.ca/
pgrc-rpc
No Yes Yes Formed
SRB Serbia IFVCNS, Novi Sad 991 http://www.nsseme.com/ en/
No No No
Code Country Institute Number of
Accessions Web Site Online Catalogue Genotyped Phenotyped Core
ISR Israel Israel Plant Gene Bank, ARO Volcani Center
343 http://igb.agri.gov.il Yes Partly Partly
TUR Turkey Aegean Agricultural Research Institute, Menemen/IZMIR
236 http://www.etae.gov.tr/eng/ No Partly Partly
ARM Armenia Institute of Botany NAS RA, Yerevan
19 http://www.sci.am/ No No No
ETH Ethiopia Institute of Biodiversity Conservation, Addis Ababa
1768 http://www.ibc.gov.et/ No No No
NBPGR India National Bureau of Plant Genetic Resources, New Delhi
3609 http://www.nbpgr.ernet.in No No Yes
BRA Brazil National Center for
Vegetable Crops Research (CNPH)/EMBRAPA
1958 http://www.cnph.embrapa.
br
No No No
Others (149) FAO report on germplasm collections
28,831 http://www.fao.org No No No Svalbard Global Seed Vault 9670 http://www.croptrust.org Yes No No
TOTAL 98,947
Code Country Institute Number of
49,248 16,910 51,450 12,396 4980 All wild (3726) 11,938 Commercial varieties (34%) Breeding lines (13%) Landraces (38%) Mutant stock (2%) RILs (3.7%) P. subsp. elatius (0,42%) P.humile/syriacum (1.2%) P. transcaucassicum, asiaticum (0.2%) P. abyssinicum (0.36%) P. fulvum (0.46%) Uknown
Figure 3.1 Stratification of pea germplasm collections listed in Table 3.1 by species, subspecies and breeding status, with indicated numbers and percentage of total. RILs, Recombinant Inbred Lines.
17,121 1588 2407 1529 298 824 1924 4670 1899 5730 152 2268 3692 923 165
Western and Central Europe Balkan
Mediterranean region Turkey–Syria Israel– Jordan–Palestine
Caucassus region (Armenia–Georgia– Azerbaijan)
Central Asia (Iraq–Iran–Turkmenistan– Pakistan–Afghanistan)
Russia–Ukraine–Kazachstan India– Nepal–Tibet China–Mongolia–Japan Africa (excluding Mediterranean) Ethiopia–Yemen
Americas
Australia–NZealand–Oceania Southeast Asia
Figure 3.2 Stratification of pea germplasm collections listed in Table 3.1 (except ETH, BRA, UKR due to lack of data) by geographical regions, with indicated numbers of accessions.
due to native habitats destruction (Maxted et al., 2010). Several attempts have been made at ex situ conservation of Vavilovia, the closest Pisum relative, especially in the former USSR, with all of them being unsuccessful likely due to inadequate cultiva- tion (Makasheva, 1973; Zhukovskyi, 1971). Some success was achieved in the United Kingdom (Cooper & Cadger, 1990), but these did not result in the production of new seeds or in multiplication of the plants. More promising results were produced in the Vavilov Institute during 1974–1981. Some plants survived for years, bloomed and even formed fruits with seeds (reviewed in Akopian et al., 2010). Vavilovia has peri- odically been grown in the Yerevan Botanic Garden since 1940, as well as is being recently cultivated in vitro (Akopian et al., 2010; Mikicˇ et al., 2013); nevertheless, this particular species in currently vulnerable to habitat destruction and climate change, and no seeds have been preserved ex situ to ensure its longer term conservation. There is an urgent need to systematically sample the genetic diversity in wild rela- tives that was only partially captured in the domestication of pea (Ellis, 2011; Smykal et al., 2011), since natural habitats are being lost due to increased human population, increased grazing pressure, conversion of marginal areas to agriculture and ecological threats due to future climate change (Keiša, Maxted, & Ford-Lloyd, 2007; Maxted & Kell, 2012). The target areas for comprehensive collection of wild relatives of peas include the habitat from the Mediterranean through the Middle East and Central Asia, as these are likely to contain genetic diversity for abiotic stress tolerances (Coyne et al., 2011). The storing of pea seeds in gene banks (ex situ) is relatively inexpensive and effective, consequently it is the most common way to preserve crop diversity. In addition to gene banks, botanical gardens offer an ex situ alternative to seed conser- vation. Gardens have usually held a broad taxonomic range and consequently often a limited number of accessions of each species, limiting their effectiveness in the genetic conservation. However, major world botanical gardens manage large seed banks (e.g. the Millennium Gene Bank managed by the Royal Botanic Gardens at Kew, UK), have well managed herbarium collections, are involved in re-introduction programmes and have DNA storage facilities (known as DNA banks). The recently funded Svalbard Global Seed Vault (Table 3.1) currently preserves 9670 pea accessions, selected from several main collections as germplasm backup. Although herbarium and DNA banks are relatively of little practical use to conserve diversity, both provide very valuable sources to study genetic diversity of crop wild relatives (CWR). Digitization and pub- lic access of herbarium vouchers allows for the study of morphological traits remotely. In the case of wild Pisum as well as its closest allies Vavilovia formosa, such digi- tized specimen resources exist in the Royal Botanic Gardens at Kew and Edinburgh, UK. Both also have good representation of the Eastern Mediterranean and Near East (Turkey, Syria, Palestine, Israel) floristic regions. In addition, some valuable col- lections of Pisum herbarium vouchers are held at Vavilov Institute and Komarov Botanical Institute, St. Petersburg, Russia, covering largely the Caucasus and Central Asia regions (Smýkal, pers. communication). In addition to botanical gardens, several universities, particularly in the Mediterranean region, have useful herbariums. These institutions often have the most direct knowledge and access to existing genetic diver- sity preserved ex situ. Unfortunately there is often an information gap between gene banks, botanical gardens and universities.
3.3.2 Conservation of the Wild Gene Pool
In light of the growing concern over the predicted devastating impact of climate change on global biodiversity and food security, coupled with a growing world popu- lation, taking action to conserve CWR has become an urgent priority. CWR are spe- cies with a close genetic similarity to crops and many of them have the potential or actual ability to contribute beneficial traits to crops, such as resistance to biotic and abiotic stresses, besides yielding related characters (Maxted, Shelagh, Ford-Lloyd, Dulloo, & Toledo, 2012). There has been no systematic effort to conserve temperate crop species in situ either through genetic reserves or on farms. Passive conservation of legume species, including pea, exists in several currently protected areas for land- scape ecosystems in the Mediterranean and Near East regions, which are not intended specifically to conserve wild crop relatives. Consequently native legume popula- tions are susceptible to genetic erosion or even extinction (Maxted, Shelagh, Ford- Lloyd, Dulloo, & Toledo, 2012). Maxted, van Slageren, and Rihan (1995) was the first to proposed establishment of genetic reserves to conserve Vicieae species in situ in Syria and Turkey. Three reserves were established within the Global Environment Facility project in Turkey (Kaya, Kün, & Güner, 1998). Recently international ini- tiatives include the Global Environment Facility projects (‘In situ Conservation of CWR Through Enhanced Information Management and Field Application’ and ‘Design, Testing and Evaluation of Best Practices for in situ Conservation of Economically Important Wild Species’), the European Community–funded project ‘European CWR Diversity Assessment and Conservation Forum (PGR Forum)’, the FAO commissioned ‘Establishment of a Global Network for the in situ Conservation of CWR: Status and Needs’, the International Union for Conservation of Nature (IUCN) Species Survival Commission CWR Specialist Group and the European ‘In Situ and On-Farm Conservation Network’. The need to address CWR conserva- tion is also highlighted in international and regional policy instruments, such as the Convention on Biological Diversity (CBD), the FAO Global Plan of Action for the Conservation and Sustainable Utilization of Plant Genetic Resources for Food and Agriculture (PGRFA) (FAO, 1996), the CBD Global Strategy for Plant Conservation, the International Treaty on PGRFA, the European Plant Conservation Strategy (Planta Europa, 2001), the Global Strategy for CWR Conservation and Use (Heywood, Kell, & Maxted, 2008) and most recently the European Strategy for Plant Conservation (Planta Europa, 2008). The latter strategy specifically recommends the establishment of 25 CWR genetic reserves in Europe and the undertaking of gap analysis of cur- rent ex situ CWR holdings, followed by filling of diversity gaps. There are a num- ber of potential approaches to systematic CWR conservation, but each requires the precise targeting of CWR diversity that can then be sampled for gene bank storage or designation and management as a genetic reserve (Maxted & Kell, 2009). There is an extensive literature on gap analysis, which is used to identify areas in which selected elements of biodiversity are underrepresented. Maxted, Dulloo, Ford-Lloyd, Iriondo, and Jarvis (2008) have adapted the existing methodologies and proposed a specific methodology for CWR genetic gap analysis that involves four steps: (a) identify priority taxa, (b) identify ecogeographic breadth and complementary
hot spots using distribution and environmental data, (c) match current in situ and
ex situ conservation actions with the ecogeographical data and complementary hot spots to identify the gaps and (d) formulate a revised in situ and ex situ conserva- tion strategy. This methodology has been applied by Maxted and Kell (2009) for 14 globally important food crop groups including pea. A combined gap analysis was undertaken for six legume genera using over 2000 unique georeferenced records; the regression analysis undertaken illustrated that none of the countries rich in Pisum species can be considered oversampled, with Turkey, the former Soviet Union (par- ticularly the countries of the Caucasus), Syria, Spain and Greece warranting further
ex situ collection, as there is a potential for finding additional diversity. In legumes, there is considerable evidence for environmental selection pressure on phenologi- cal traits. Habitats that impose high terminal drought stress select for early flower- ing and short life cycles as a drought escape mechanism, whereas cool, high rainfall habitats select for delayed phenology, allowing more biomass production and sup- porting a higher reproductive effort. This has been demonstrated in a variety of wild and domesticated Mediterranean annuals, including legumes (reviewed in Upadhyaya et al., 2011), and confirms that habitat characterization is an essential and useful eco- physiological tool to explore the mechanisms underlying specific adaptations (Berger et al., 2012). A recent Global Environment Facility funded project, ‘Conservation and Sustainable Use of Dryland Agrobiodiversity in West Asia’ established two genetic reserves in northeast Lebanon at Arsal and Balbak to conserve genetic diversity of wild forage legumes, fruit trees, vegetables and cereals. Both sites contain significant
Cicer, Lathyrus, Lens, Medicago, Pisum and Vicia priority crop species diversity, including both P. sativum subspecies and P. fulvum.
3.3.3 Pea Mutant Collections
Pea has a large number of mutant lines, either spontaneous or induced. It has been used as a model plant species for experimental morphology and physiology in muta- genic studies. Numerous morphologically well-described mutants exist, many of them being used in genetic mapping. The earliest collection lists 21 pairs of cultivated pea lines for contrasting characters covering plant form, foliage, flowers, pods and seeds, which were the subject of genetic investigation, held within a collection of 550 culti- vars (Vilmorin, 1913). Later, Blixt (1972) made a list and linkage group positions of 169 genes (loci) which occurred spontaneously or were induced. Induced mutagen- esis has become widespread for the creation of novel genetic variation for selection and genetic studies (Blixt, 1972; Lamm, 1951; Lamprecht, 1964) with mutants in traits for physiology, chlorophyll, seed, root, shoot, foliage, inflorescence, flowers and pods. These genetic analyses contributed to Pisum genus classification. The mutant collections have been largely preserved in John Innes Centre (JIC) (585 accessions) and Nord Genebank (Blixt & Williams, 1982). Partial duplicates exist at Polish (297) and Bulgarian (150 accessions) gene banks (Table 3.1). In addition Murfet and Reid (1993) have developed and maintain developmental mutants in Tasmania. There is a pea population of 4817 lines newly established by the technique of targeting induced local lesions in genomes (TILLING) at Institut National de la Recherche Agronomique
(INRA) (Table 3.1). In addition, fast neutron-generated deletion mutant resources (around 3000 lines) are available for pea, which have been useful in identifying several developmental genes (Hellens et al., 2010; Hofer et al., 2009; Wang et al., 2008).