ABSTRACT

A new cytoplasmic male sterility (CMS) and restoration system denoted as CMS-D8 and D8 restorer, which was developed by transferring cytoplasm and restorer gene from the American diploid wild species, Gossypium trilobum Skov. (D₈ genome) into cultivated tetraploid cottons (G. hirsutum L. and G. barbadense L.), can be utilized for economic hybrid cotton seed production. Two independent dominant restorer genes, Rf₁ from the D2 restorer line transferred from G. harknessii Brand (D₂ genome) and Rf₂ from the D8 restorer line were identified. The objectives of the present study were, (1) to test the efficiency of a set of MtDNA universal primers in cotton; and (2) to identify potential MtDNA markers that can be used to differentiate CMS-D2 and CMS-D8 cytoplasms in comparison with upland cotton normal fertile cytoplasm. Of 36 primer pairs designed for amplifying introns, intergenic regions, or genes on cotton MtDNA genome, 16 pairs produced amplifications with expected fragment sizes based on Arabidopsis thaliana MtDNA genome sequence, with the exception of nad7 and rps12. Our work using MtDNA universal primers revealed no STS polymorphism among the three cytoplasms (AD1, D2 and D8), confirming that MtDNA genes in cotton are highly conserved in sequences as in other plant species. DNA sequencing on the amplified products could identify SNPs in the CMS cytoplasms in comparison with the normal fertile AD1 cytoplasm.