**7.2 Approaches**

12 Soybean – Genetics and Novel Techniques for Yield Enhancement

(Brown-Guedira *et al*., 2000; Narvel *et al*., 2000; Fu *et al.,* 2007; Hwang *et al*., 2008). Baranek *et al*. (2002) evaluated genetic diversity of 19 G*lycine max* accessions from the Czech National Collection using RAPD markers. Recently, Tavaud-Pirra *et al.* (2009) evaluated SSR diversity of 350 cultivated soybean genotypes including 185 accessions from INRA soybean collection originating from various European countries and 32 cultivars and recent breeding lines representing the genetic improvement of soybean in Western Europe from 1950 to 2000. They found the genetic diversity of European accessions to be comparable with those of the Asian accessions from the INRA collection, whereas the genetic diversity observed in European breeding lines was significantly lower. Breeding material and registered soybean cultivars in southeast European countries are strongly linked to Western breeding programs, primarily in the USA and Canada. There is little reliable information regarding the source of germplasm introduction, its pedigree and breeding schemes applied. Consequently, use of these genotypes in making crosses to develop further breeding cycles can result in an insufficient level of genetic variability. Assessing the genetic diversity of this germplasm at genomic DNA level would complement the knowledge on the European soybean gene pool (germplasm) and facilitate the utilization of the resources from southeastern Europe by soybean breeders. Ristova *et al*. (2010) therefore assess genetic diversity and relationships of 23 soybean genotypes representing several independent breeding sources from southeastern Europe and five plant introductions from Western Europe and Canada using 20 SSR markers. Cluster analysis clearly separated all genotypes from each other assigning them into three major clusters, which largely corresponded to their origin. Results of clustering were mainly in accordance with the known pedigrees.

The use of functional molecular markers, such as those developed from EST allows direct access to the population diversity in genes of agronomic interest that they represent coding sequences, facilitating the association between genotype and phenotype. Nelson and Shoemaker (2006) identified approximately 45,000 potential gene sequences (pHaps) from EST sequences of Williams/Williams 82, an inbred genotype of soybean (*Glycine max* L. Merr.) using a redundancy criterion to identify reproducible sequence differences between related genes within gene families. Analysis of these sequences revealed single base substitutions and single base indels are the most frequently observed form of sequence variation between genes within families in the dataset. Genomic sequencing of selected loci indicates that intron-like intervening sequences are numerous and are approximately 220 bp in length. Functional annotation of gene sequences indicates functional classifications are not randomly distributed among gene families containing few or many genes. The identification of potential gene sequences (pHaps) from soybean allows the scientist to get a picture of the genomic history of the organism as well as to observe the evolutionary fates of

Exploitation of gene banks for efficient utilization depends on the knowledge of genetic diversity, in general, and allelic diversity at candidate gene(s) of interest, in particular. Hence, allele mining seems to be a promising in characterization of genetic diversity or allelic/genic diversity among the accessions of the collection in terms of its utility for

**6.6 EST (Expressed Sequence Tags )** 

gene copies in this highly duplicated genome.

**7. Allele mining in soybean germplasm** 

**7.1 Concept** 

Two major approaches are available for the identification of sequence polymorphisms for a given gene in the naturally occurring populations: (1) modified Targeting Induced Local Lesions in Genomes (TILLING) procedure and (2) sequencing based allele mining.
