Core collections in vegetable crops
Author: Dr. Palanisamy Muthukumar

Core collections is a subset of large germplasm collections that generally contains about 10% of the total accessions and represents the genetic variability of entire germplasm collections to capture most of available genetic diversity of the species (Frankel, 1984). The purpose of a core collection is to improve the use of genetic resources prebreeding programme. In many vegetable crops the number of accessions in the genebank vary from several thousands to hundreds.

Mini core collections (10% of the core or 1% of entire collections) developed to enhance the use of germplasms for trait discovery (Upadhyaya, 2001). There are several genes were effectively exploited in exotic germplasm by introgressing gene(s) for diseases resistance or quality traits. However, the use of exotic germplasm in the improvement of quantitative traits is very limited. In last 50 years vegetable genetic resources are being lost, on a global scale at the rate of 1–2% per year. Vegetable breeding has to address and satisfy the needs of both the consumer and the farmer. The general objectives for farmers are good yield, disease and pest resistance, uniformity and abiotic stress resistance. One of the best example for utilization of tomato wild relatives for improvement of disease resistance and pest of cultivated tomato through pre breeding strategies. Virtually all significant disease resistance genes to tomato diseases were originated from different wild relatives.

Source of vegetable core collections and germplasms centres

1. G2P-SOL: Linking genetic resources, genomes and phenotypes of Solanaceous crops

The main aim of G2P-SOL to access germplasm diversity of four major Solanaceous crops potato, tomato, pepper and eggplant. The currently, available germplasm in genebanks and their uses of these exotic germplasm for crop improvement is limited. This is mainly due to the lack of information and data available to the user community to compare the plant collections and accessions held in different genebanks all over the world and to choose those best suited for their location, environmental conditions and needs. These four crops constitute 66% of the value of European horticultural production, and over 65,000 accessions are available within the consortium.

2. EU-SOL BreeDB database

This site hosts data-sets collected within the framework of the European project EU-SOL. This site is roughly divided into two sections (tomato core collection data and experimental populations information). The tomato core collection is composed of ~7000 domesticated tomato lines, and their wild relatives.

3. CGN Vegetable Brassicas

CGN developed the European Brassica Database (Bras-EDB) in the framework of the Brassica Working Group of the European Cooperative Programme for Crop Genetic Resources Networks (ECP/GR). CGN collection of cruciferous crops includes 1750 accessions. The collection contains mainly cultivars (1080), furthermore landraces (294) and research material (181). B. oleracea is represented with the highest number of accessions followed by B. rapa, Raphanus sativus, B. napus and B. carinata. This core collections were available resistance to Fusarium oxysporum, Plasmodiophora brassicae and Thrips tabaci

4. CGN: cucumber collection

The cultivated cucumber about 937 accessions were available for breeding purpose. A few accessions of the subspecies C. sativus var. hardwickii and C. sativus var. sikkimensis are present. It is one of the largest collections in Europe and comprises of 375 cultivars, 126 landraces, 17 research lines, 5 accessions of C. sativus var. hardwickii. Around 300 CGN cucumber accessions have been tested for cucumber green mottle mosaic virus (CGMMV) by breeding companies.

5. UK Vegetable Genebank (UKVGB)

In 1980, concern over the loss of genetic diversity in vegetable crops and the potential impact this would have on global nutrition and health led to the creation of the currently managed by the University of Warwick. The UKVGB currently conserves approximately 14,000 accessions of crops such as alliums, brassicas, carrot, and lettuce, as well as smaller collections of minor vegetables and salad crops. Research resources such as the European Clubroot Diversity set (ECD) and the Brassica S-allele collection, are also hosted at the UKVGB.

6. World vegetable centre: Tomato

The section Lycopersicon in the genus Solanum is well represented in ex situ collections around the globe about 82,400 accessions. The single largest collection (approximately 10% of total global resources) is held by The World Vegetable Center in Taiwan. The tomato collection of AVRDC is composed of 6,142 S. lycopersicum accessions mostly traditional cultivars and landraces, 125 S. lycopersicum var. cerasiforme accessions, 812 accessions of wild tomato relatives. The S. pimpinellifolium collection is the largest one and comprises 330 accessions. The S. pimpinellifolium, core collection composed of 75 accessions represent 22.7% of entire S. pimpinellifolium collection.

7. TG RC: Tomato

The C.M. Rick Tomato Genetics Resource Center at UC Davis, a genebank of mutants, wild relatives and other genetic stocks, is an irreplaceable source of the genetic traits used to improve yield, stress adaptation, disease resistance, and flavour and fruit quality of tomato varieties. Several wild species core collections were available to utilize for breeding programmes

References

1. Upadhyaya, H D and Gowda, C L L and Pundir, R P S and Ntare, B R (2007) Use of core and mini core collections in preservation and utilization of genetic resources in crop improvement. In: Plant genetic resources and food security in West and Central Africa. Regional Conference, 26-30 April 2004, Ibadan, Nigeria.

2. van Hintum TJL, Brown AHD, Spillane C, Hodgkin T (2000) Core collections of plant genetic resources. IPGRI Technical Bullletin No. 3. International Plant genetic Resources Institute, Rome.



About Author / Additional Info:
I am currently working as a Scientist (ICAR-ARS) from Indian Agricultural Research Institute.