Fertility restoration in three CMS systems of eggplant by the Rf genes of each other's systems and their SCAR marker

Abstract

Three pollen non-formation type cytoplasmic male sterility (CMS) systems of eggplant (Solanum melongena L.) were developed in our previous study, through repeated backcrossing, by using wild Solanum species Solanum aethiopicum L. Aculeatum Group, Solanum anguivi Lam. and Solanum grandifolium C. V. Morton as the cytoplasm donor and eggplant ‘Uttara’ as the recurrent pollen parent. Each CMS system has male fertile (MF) line which carries the fertility restorer (Rf) genes for the pollen non-formation type sterility. In the present study, fertility restoration ability in three CMS systems of eggplant by the Rf genes of each other's systems was evaluated. The male sterile (MS) line of each CMS system was pollinated with the pollen of MF lines of other CMS systems as well as its own CMS system. Among the nine cross combinations, six groups were obtained from crossing MS lines with MF lines of other CMS systems and three groups were obtained from crossing MS lines with MF lines of their own CMS system. The segregation of MF and MS plants was fitted well with a 3:1 ratio in almost all cross combinations. The segregation patterns revealed that two independent dominant Rf genes restore fertility in each CMS system. Pollen stainability and in vitro pollen germination rate of the progenies obtained from different cross combinations were varied from 61.0 to 89.8% and 0.7 to 8.0%, respectively. Each Rf gene of three CMS systems restores fertility of other CMS systems as well as its own CMS system. Moreover, fertility recovery action in these three kinds of CMS is similar. DNA markers linked to Rf genes were screened by bulked segregant analysis (BSA) using random amplified polymorphic DNA (RAPD). A total of 420 primers were used, and more than 65% of the primers yielded a considerable number of RAPD fragments in both MF and MS bulks. Only one Operon primer OPAB10 gave a reproducible polymorphic band of 1.9kbp (OPAB101900) between bulks and was identified as linked to the Rf genes. Additionally, the RAPD marker OPAB101900 was converted to sequenced characterized amplified region (SCAR) marker designated as SCAB101900 by nucleotide sequencing. Findings of the present study may give us a potential way to explore CMS and the corresponding Rf genes from wild Solanum resources for the breeding program of eggplant.