PCR identification of Petunia male sterile cytoplasm

Petunia is a very important ornamental plant with a broad range of flower colour and size, and most of the cultivars grown are propagated through seeds. Cytoplasmic male sterility (CMS) is a maternally inherited character determined by mitochondrial genes that results in impaired pollen development. The unique and well characterized male sterile cytoplasm in Petunia is a valuable resource for hybrids production because it prevents self-fertilization of mother plants and ensures the purity of F1s. Introgression of the male sterile cytoplasm in elite lines of Petunia is achieved following a backcross scheme and can be assisted using molecular markers associated to the trait of interest. The objective of this study was to develop a molecular marker to identify the male sterile cytoplasm of Petunia . A PCR-based marker amplifying a region of the mitochondrial CMS-associated urfS only in the male sterile plants was designed. Results showed differential PCR amplification of a ≈ 600 bp product in plants carrying male sterile cytoplasm in four Petunia species and their F1s and BC1 generations. A multiplex PCR reaction was subsequently set up, adding specific primers amplifying a ≈ 800 bp product from the conserved region trnT-trn-L of the chloroplast genome as a positive control in order to unambiguously identify the cytoplasm types as normal or sterile. A rapid, simple and precise molecular marker is now available for assisting breeding of F1 hybrids in Petunia .