Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/10/2008
Publication Date: 9/1/2009
Citation: Wang, F., Yue, B., Hu, J., Stewart, J.M., Zhang, J. 2009. A Target Region Amplified Polymorphism (TRAP) Marker for Fertility Restorer Gene Rf1 and Chromosomal Localization of Rf1 and Rf2 in Cotton 2009. Crop Science 49:1602-1608.
Interpretive Summary: Fertility restorer genes are not only crucial for hybrid seed production using the cytoplasmic male sterility system but also useful in basic research to study cytoplasm-nuclear interaction in various plant species. In cotton, two male sterile cytoplasms and respective restorer genes have been reported. However, molecular markers tightly linked to the restorer genes are scarce. Aimed to develop DNA markers linked to restorer genes, this project used two backcross (BC1F1) populations and employed the recently developed target region amplified polymorphism (TRAP) marker technique. It has been reported that the fertility restorer genes cloned from other plant species such as petunia, radish and rice are members of the pentatricopeptide repeat (PPR) gene family. One TRAP marker tightly linked to Rf1 gene was amplified with a fixed primer containing PPR sequence. With three mapped common SSR markers in the two populations, both restorer genes, Rf1 and Rf2 are mapped on chromosome D5 on the consensus genetic linkage map constructed with computer software JoinMap. Our result will facilitate fine mapping to elucidate the organization of the two restorer genes and, eventually, cloning them by map-based strategy.
Technical Abstract: Cytoplasmic male sterility (CMS), a maternally inherited trait and characterized as an inability to produce functional pollen , is an important biological system for economically producing hybrid seed to enhance crop yield and studying cytoplasmic and nuclear gene interactions. In cultivated tetraploid cotton, male fertility in two systems CMS-D2 and CMS-D8 is restored by two restorer genes Rf1 and Rf2, respectively. The objectives of the present study were to identify additional molecular markers for the two restorer genes and to determine their chromosomal location in the cotton genome. Two backcross (BC1F1) populations were developed with D2 and D8 restorers containing their respective cytoplasms as female in crosses with the same Upland cotton maintainer as male and recurrent parent. One pentatricopeptide repeat (PPR)-based target region amplified polymorphism (TRAP) marker was developed to be tightly linked to Rf1 gene with a genetic distance of 0.8 cM, while three more SSR markers (NAU2232-550/650, NAU2232-750/850, and NAU 2801-250) were identified to be closely linked to Rf2. Using three common SSR markers, a consensus linkage group was constructed to include both the Rf1 and the Rf2 locus. Based on several chromosome-anchored SSR markers, Rf1 and Rf2 were localized on chromosome D5 and anchored in a 14.6 cM region by two PPR gene-based markers, providing an incentive for further investigations of this Rf1/Rf2- containing region.