Genetic Mapping of the Unstable Restorer-of-fertility Gene in Sweet Pepper (Capsicum annuum L.)

Abstract

Cytoplasmic-genic male sterility (CGMS) has been used for F1 hybrid seed production in several crop plants. The CGMS system is determined by interaction between cytoplasm male sterility (CMS) associated mitochondrial gene and the Restorer-of-fertility (Rf) gene in nucleus. In the previous studies, several Rf-linked markers and candidate genes were identified. However, the unstable Rf genes that are affected by environmental conditions has rarely been studied. In this study, we investigated on the male fertility phenotype of the unstable Rf gene and developed markers linked to the unstable Rf gene. The male fertility phenotype was inherited as a 3:1 ratio in a population derived from a cross between MSGR-A with stable sterility (rf/rf) and SPR03 with unstable fertility (Rfu/Rfu) indicating that the unstable Rf gene is controlled by a single dominant gene in the permissive temperature. Genetic mapping revealed that 214.14MB-CAPS is co-segregation with the unstable Rf locus. Candidate genes were predicted using the sequences within the delimited region between 13T7-SCAR and G16-SCAR. A total of 37 and 80 predicted genes were detected in the target region from Zunla-1 and CM334 (UCD 10X), respectively. Predicted genes related to unstable Rf couldnt be found in Zunla-1. However, In CM334 (UCD 10X), pentaricopeptide (PPR) gene, protein gamete expressed 2 (GEX 2) and peroxidase were detected in the target region. 214.14MB-CAPS which is co-segregated with unstable Rf showed high accuracy of genotype (91.6%) in unstable fertile lines. Application of marker co-segregated with unstable Rf can be broadly use unstable male fertile lines. However, stable male sterile could not be distinguished. Phylogenetic tree based on the genotype of several markers showed that stable or unstable lines were prone to be cluster together.