Analysis of population structure and genetic diversity of Egyptian and exotic rice (Oryza sativa L.) genotypes

Understanding the population structure and genetic diversity is a very important goal to improve the economic value of crops. In rice, a loss of genetic diversity in the last few centuries is observed. To address this challenge, a set of 22 lines from three different regions - India (two), and Philippines (six), and Egypt (14) - were used to assess the genetic diversity and the features of population structure. These genotypes were analyzed using 106 SSR alleles that showed a clear polymorphism among the lines. Genetic diversity was estimated based on the number of different alleles, polymorphism information content (PIC), and gene diversity. A total of 106 SSR alleles was identified from the 23 SSR loci and used to study the population structure and carry out a cluster analysis. All SSR loci showed a wide range of the number of different alleles extended from two (one loci) to seven alleles (three loci). Five and eight loci showed high PIC and gene diversity (≥0.70), respectively. The results of population structure are in agreement with cluster analysis results. Both analyses revealed two different subpopulations (G1 and G2) with different genetic properties in number of private alleles, number of different alleles (Na), number of effective alleles (Ne), expected heterozygosity (He), and Shannon's Information Index (SII). Our findings indicate that five SSR loci (RM 111, RM 307, RM 22, RM 19, and RM 271) could be used in breeding programs to enhance the marker-assisted selection through QTL mapping and association studies. A high genetic diversity found between genotypes which can be exploited to improve and produce rice cultivars for important traits (e.g. high agronomic features and tolerance to biotic or/and abiotic stresses).