The distribution of normal and male-sterile cytoplasms in Chinese sugar-beet germplasm

Forty-two Chinese sugar-beet breeding lines were evaluated for the presence of normal and male-sterile (Owen) cytoplasms using polymorphisms in the chloroplast petG-psbE region as well as in the mitochondrial minisatellite loci. The polymorphisms detected allowed the distinction of three cytoplasm types over the whole sample, one being associated with Owen cytoplasm, a second with the maintainer inbred 'TK-81mm-O'-type cytoplasm (termed normal-1 cytoplasm) and a third with another maintainer inbred 'NK-310mm-O'-type cytoplasm (normal-2 cytoplasm). Western blot analysis was carried out to confirm that expression of the male-sterility-associated protein (preSATP6) occurred in plants with Owen cytoplasm but not in plants with either normal-1 or normal-2 cytoplasm. Of the 42 breeding lines examined, 14 had exclusively normal (normal-1 and/or normal-2) cytoplasm and 11 had only Owen cytoplasm. The remaining 17 lines possessed both normal and Owen cytoplasms, and noticeably, some of these 17 lines have been expected to become the source of superior maintainer lines. The results thus show that molecular identification of the cytoplasm is required to avoid wasting resources on account of attempting to develop the maintainer genotype from plants with Owen cytoplasm.