MULTIPLE METHODS FOR THE IDENTIFICATION OF POLYMORPHIC SIMPLE SEQUENCE REPEATS (SSRS) IN SORGHUM [SORGHUM-BICOLOR (L) MOENCH]

Simple sequence repeats (SSRs), also known as microsatellites, are hig hly variable DNA sequences that can be used as markers for the genetic analysis of plants, Three approaches were followed for the developmen t of PCR primers for the amplification of DNA fragments containing SSR s from sorghum [sorghum bicolor (L.) Moench]: a search for sorghum SSR s in public DNA databases; the use of SSR-specific primers developed i n the Poaceae species maize (Zea mays L.) and seashore pas palum grass (Paspalum vaginatum Swartz); and the screening of sorghum genomic lib raries by hybridization with SSR oligonucleotides. A total of 49 sorgh um SSR-specific PCR primer pairs (two designed from GenBank SSR-contai ning sequences and 47 from the sequences of genomic clones) were scree ned on a panel of 17 sorghum and one maize accession. Ten primer pairs from paspalum and 90 from maize were also screened for polymorphism i n sorghum. Length polymorphisms among amplification products were dete cted with 15 of these primer pairs, yielding diversity values ranging from 0.2 to 0.8 with an average diversity of 0.56. These primer pairs are now available for use as markers in crop improvement and conservat ion efforts.