PPR-B-31: a new maintainer allele in the male-fertility restorer gene of radish (Raphanus sativus) Ogura cytoplasm

摘要

The PPR-B gene is responsible for male-fertility restoration of the Ogura-type male-sterile radish plants, and it is located in the complex Rfo locus in the vicinity of similar PPR-A gene and PPR-C pseudogene. The aim of this study was to identify PPR-B alleles and understand the structure of the Rfo locus in radish breeding lines. Five lines of radish with normal male-fertile cytoplasm were tested. The entire PPR-B gene was amplified, sequenced and allelic PPR-B sequences were identified. The results indicated that the maintainer lines 7, 15 and 21 contained a non-restoring form of PPR-B protein. A unique PPR-B was found in lines 24/15 and 31 that are restorer and maintainer lines, respectively. The substitutions might be responsible for the loss of a restoring function of the PPR-B-31 allele. Amplification of the PPR-A/PPR-B and PPR-B/PPR-C intergenic regions allowed to identify rearrangements within Rfo locus. Obtained results confirm the wide allelic variation within the Rfo locus, as well as high genetic complexity of the fertility restoration mechanism in radish.