A Sequence Specific PCR Marker for Distinguishing Rice Lines on the Basis of Wild Abortive Cytoplasm from Their Cognate Maintainer Lines

Abstract

Ensuring the genetic purity of parental lines and hybrids is a prerequisite to realize their full potential. The cytoplasmic male sterile (CMS) lines that are utilized for developing the popular "three-line" hybrids, often get contaminated with their isonuclear maintainer lines during CMS line multiplication. Use of such CMS lines in hybrid seed production results in the production of genetically impure hybrid seed. We report the identification of a DNA sequence that is homologous to rice mitochondrial DNA but unique to the Wild Abortive (WA) cytoplasmic male sterile lines of rice (Oryza sativa L.). In a polymerase chain reaction (PCR) using total genomic DNA as a template, oligonucleotide primers based on this unique DNA sequence could amplify a fragment from CMS lines of rice and their hybrids but not from their cognate maintainer lines. In tests on mixed samples of plants containing both CMS and Maintainer lines, this PCR assay was used to correctly predict the genotypes of these plants indicating that it can be used to detect the mixture of maintainer lines in the seed stocks of the CMS line.