Molecular characterization and genetic relationships among cotton genotypes: 1- RAPD, ISSR and SSR analysis [electronic resource].

Includes references.

Cotton is the world's leading fiber crop and the second important oil seed crop. Recent advances in genomics research have provided new tools, such as molecular markers, that will assist breeders in the improvement of this important crop. Use of molecular markers in genome analysis, mapping of agriculturally important trails and marker-assisted selection have been greatly advanced by the development of PCR-based markers. The present study is a port of a cotton genomics project that addresses the use of different PCR-based molecular markers (RAPD, ISSR and SSR) for germplasm characterization, fingerprinting and assessing the genetic diversity among some of the accessions available at the cotton Research Institute. ARC, Egypt, Twenty-one cotton accessions were assayed using 28 RAPD and 12 ISSR primers, in addition to 24 SSR specific primer pairs. The total number of amplicons detected by HAPD, ISSR and SSR was 323, 125 and 62, respectively. While, the number of polymorphic amplicons was 191, 62 and 39, respectively. Thus., the level of polymorphism among the 21 accesssions as revealed by HAPD, ISSR and SSR was 59.1%, 49.6 and 62.9 respectively. The genetic relationships among the 21 accessions were estimated in terms of similarity using the Dice coefficient, The topology of the dendrograms derived from the different marker types was unique, however, with evident similarities, All dendrograms clearly c1ustered the accessions belonging to G. hirsutum in one group and those of G. barbadense, expect Pima Early American, in another group. One out of the 28 RAPD primers produced 21 different banding patterns, thus, identifying each of the 21 accessions by a unique bonding profile, Two ISSR primers (S1 and S2) revealed 18 handing patterns each and together made it possible the identification of all the genotypes. Moreover. accession-specific DNA markers characterized different genotypes and therefore were used to generate unique fingerprint for each genotype. The HAPD, ISSR and SSR detected 4,8 and 5 unique positive and/or negative markers characterizing 3, 4 and 4 accessions, respectively. Furthermore, five SSR alleles (Mg₂₈₀, Mg₂₉₀, C11₂₅₀, C11₂₆₀ and M13₁₅₀) could the discriminate between accessions belonging to the species G. borbadense and thosc of G. hirsutum. Thus, they were considered as species-specific markers.

Summary in Arabic.

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