Computational and experimental characterization of physically clustered simple sequence repeats in plants

Area of Science:

• Genomics
• Molecular Biology

Background:

• Simple sequence repeats (SSRs) are repetitive DNA sequences found throughout plant genomes.
• Understanding SSR distribution is crucial for genetic mapping and marker development.

Purpose of the Study:

• To investigate the frequency and types of SSRs in plant genomes using public DNA sequence data.
• To develop and demonstrate a practical method for targeted SSR isolation linked to specific genes.

Main Methods:

• Analysis of large datasets of genomic DNA and expressed sequence tags (ESTs) from Arabidopsis to determine SSR frequency and distribution.
• Development of a strategy involving sample sequencing of BAC subclones to isolate SSRs.
• Application of the method in barley to locate a specific gene (Big1).

Main Results:

• SSRs occur frequently in plant genomes, with an average frequency of one per 6.04 kb in genomic DNA and one per 14 kb in ESTs.
• SSR frequency and type vary significantly between coding, intronic, and intergenic regions.
• The proposed method successfully identified three SSRs in barley BACs, enabling the localization of the Big1 gene.

Conclusions:

• SSRs are a valuable resource for plant genetic studies and marker-assisted selection.
• The demonstrated method provides a feasible and efficient approach for targeted SSR isolation and gene mapping in plants.
• This technique can accelerate gene discovery and breeding programs by linking SSRs to mapped genes.