ABSTRACT

Systematic collection, evaluation, enhancement, conservation and documentation of Brassica Oilseed Genetic Resources have been carried since 1986 in China. Now a Brassica Oilseed Base Collection has been set up in Oil Crops Research Institute of CAAS in Wuhan, which contain near 7000 accessions of germplasm, including landrace, cultivars , breeding materials and wild relatives. All accessions have been multiplied and conserved in National Genebank and Oil Crops Research Institute of CAAS in duplicate.

Important agro-morphological characters (growth period, time of flowering and seed maturation, leaf colour , leaf shape, flower colour, plant height, height of 1^st branch, number of branches, number of siliques, number of seeds/silique, seed coat colour, 1000 seed weight, , length of inflorescence ); quality traits ( oil content, protein content, fatty acid composition and glucosinolates content and profile), disease resistance to Sclerotinia Rot, Downey mildew and Virus have been identified and measured. Many elite or special accessions with good agronomic characters, high quality or disease resistance were screened out. A computerized database containing passport data and evaluation data was established.

RAPD and AFLP have been employed to study the genetic diversity in the Base Collection, incorporated with the passport data and evaluation data, a core collection is now under construction.

INTRODUCTION

The Brassica oilseed germplasm is the basis for the improvement and sustainable utilization of Brassica oil seeds. The research of Brassica oilseed genetic resources has been given a high priority in China, three successive China National Five Year Agricultural Key Projects ( 1986-1990, 1991-1995, 1996-2000 ) aim at collection, evaluation, enhancement, conservation and documentation of Brassica genetic resources granted by the Government have been carried out. A Brassica Oilseed Base Collection has been set up in Oil Crops Research Institute of CAAS in Wuhan, which comprising near 7000 accessions of germplasm, including landrace, cultivars , breeding materials and wild relatives. Important agro-morphological characters, quality traits and disease resistance were identified and evaluated. A new National Natural Science Foundation of China Key Project has started to assess the genetic diversity in the Base collection by integrate using of molecular markers and multivariate analysis of passport and evaluation data.

1. The species and origin of the accessions in the Brassica Base Collection

Up to now 6259 accessions of Brassica oilseeds germplasms have been collected in China or introduced from abroad, which formed the Chinese Brassica Base Collection. New collecting mission will be initiated to collect the endangered germplasm in the region of the Three Groge, the accession number will reach 7000 by the year of 2000.

Table 1. The species and origin of the accessions in the Brassica Base Collection

2. Characterization of Brassica germplasm for agro-morphological triats

Important agro-morphological traits, including growth period, time of flowering and seed maturation,, leaf colour , leaf shape, flower colour, plant height, height of 1^st branch, number of branches, number of siliques, number of seeds/silique, seed coat colour, 1000 seed weight, length of inflorescence, were recorded and measured in the original geographical area of the accessions.

3. Assessment of Brassica oilseeds germplasm for quality traits

Tables 2, 3 and 4 show the partial results of chemical quality assessment:

Table 2. The oil and protein content (%) of Brassica oilseeds

Table 3. The variation of fatty Acid composition (%) in Brassica oilseeds

Table 4. The variation of individual glucosinolates (μmol /g )in of Brassica oilseeds

4. Identification of Brassica oilseeds germplasm for disease resistance

Tables 5, 6 and 7 show the results of disease resistance identification:

Table 5. The disease resistance to Sclerotinia sclerotiorum

HR- High resistant, MR-Medium resistant, LR-Low resistant, LS-Low susceptible, MS-Medium susceptible, HS-High susceptible,

Table 6. The disease resistance to Peronspora parasitica

HR- High resistant, MR-Medium resistant, LR-Low resistant, LS-Low susceptible, MS-Medium susceptible, HS-High susceptible,

Table 7. The disease resistance to Virus

HR- High resistant, MR-Medium resistant, LR-Low resistant, LS-Low susceptible, MS-Medium susceptible, HS-High susceptible,

5. Documentation and establishment of database of Brassica genetic resources

The Catalogues of Chinese Brassica Oilseed Genetic Resources comprising passport and all evaluation data of the 6259 accessions were edited, and a corresponding Database of Chinese Brassica Oilseed Genetic Resources was created in a Foxbase +2.0 style.

6. Long-term and medium-term conservation of Brassica genetic resources

All accessions have been multiplied and conserved in National Genebank ( -18 ℃ ) as long-term storage and in Oil Crops Research Institute of CAAS as medium-term storage, the medium-term germplasm are accessible to rapeseed breeders and other researchers.

7. Assessment of genetic diversity of Brassica oilseed genetic resources

The genetic resources were firstly grouped by the geographical origin of each accesion, secondly, the geographical groups were stratified according to the cluster analysis of evaluation data, then RAPD and AFLP have been employed to study the genetic variation and relatedness within and among different groups or clusters, Finally, the distribution of genetic diversity in the Base Collection are expected to be revealed .Based on the distribution of genetic diversity in the Base Collection , a Brassica Core Collection of 10% of the size of the Base Collection is under construction, which are expected to capture 90% of the genetic diversity in the Base Collection.

ACKNOWLEDGEMENTS

The authors are grateful to the Chinese Committee of Sciences and Technology and The National Natural Sciences Foundation of China for support of the studies.