RFLP analysis of mitochondrial DNA from cytoplasmic male sterile lines of pearl millet
1994
Rajeshwari, R. | Sivaramakrishnan, S. | Smith, R.L. | Subrahmanyam, N.C. (Hyderabad Univ., Gachibowli (India). School of Life Sciences)
Mitochondrial DNA (mtDNA) from 13 cytoplasmic male-sterile (cms) lines from diverse sources were characterized by Southern blot hybridization to pearl millet and maize mtDNA probes. Hybridization patterns of mtDNA digested with PstI, BamH1, Sma1 or Xho1 and probed with 13.6-, 10.9-, 9.7- or 4.7-kb pearl millet mtDNA clones revealed similarities among the cms lines 5141 A and ICMA 1 (classified as the S-A1 type of cytoplasm based on fertility restoration patterns), PMC 30A and ICMA 2. The remaining cms lines formed a distinct group, within which 3 subgroups were evident. Among the maize mitochondiral gene clones used, the cox1 probe revealed two distinct groups of cytoplasms similar to the pearl millet mtDNA clones. The atp9 probe differentiated the cms line 81 A4, derived from P. glaucum subsp. monodii, while the cox2 gene probe did not detect any polymorphism among the cms lines studied. MtDNA digested with BamH1, Pst1 or Xho1 and hybridized to the atp6 probe revealed distinct differences among the cms lines. The maize atp6 gene clone identified four distinct cytoplasmic groups and four subgroups within a main group. The mtDNA fragments hybridized to the atp6 gene probe with differing intensities, suggesting the presence of more than one copy of the gene in different stoichiometries. Rearrangements involving the cox1 and/or rrn18-rrn5 genes (mapped within the pearl millet clones) probably resulted in the S-A1 type of sterility. Rearrangements involving the atp6 gene (probably resulting in chimeric form) may be responsible for male sterility in other cms lines of pearl millet.
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