Genetic Diversity of Cytoplasmic Male Sterile Lines of Rice (Oryza sativa L.) Using Microsatellite Markers

Abstract

The maintenance of genetic diversity in the parental lines of the Cytoplasmic Male Sterile (CMS) system is important in the development of heterotic blocks that assures the production of high yielding hybrid rice. The genetic diversity within the rice samples was investigated through Hexadecyltrimethylammonium bromide (CTAB) DNA extraction, Polymerase Chain Reaction (PCR) amplification of microsatellite markers, Polyacrylamide gel electrophoresis (PAGE), and visualization by ethidium bromide staining. A total of 305 alleles were detected and the Polymorphism Information Content (PIC) ranged from 0.61 to 0.97 with an average of 0.89. All the microsatellite markers utilized in the study were polymorphic, however only 7 were highly informative. A graphical genotype of the CMS lines was constructed based on the marker profiles, which detected 34 unique alleles across 25 CMS lines with 21 microsatellite markers. Analysis of the genetic relationships among the CMS lines produced two genetically diverse clusters separated by their close relationship either with traditional varieties of diverse geographical origins or International Rice Research Institute (IRRI) bred parental lines. The results suggested that the 62 CMS lines of rice were genetically diverse and the usefulness of microsatellites as molecular markers for evaluating the genetic diversity of rice samples was reaffirmed. The marker profiles presented in the form of graphical genotype aided in the selection of appropriate markers and in the identification of selected CMS lines through the detected unique alleles.