High level of RNA synthesis in mitochondria of spontaneous and induced corn mutants

We found that the rate of mitochondrial DNA transcription in the mitochondria isolated from dwarf mutant A344 sin/sin seedlings proved much higher than in A344 + / + (MNL 61:61, 1987). The high level of mtRNA synthesis was revealed for the mitochondria of newly induced small kernel mutant Gb334 meg/meg (MNL 60:70, 1986) and spontaneous mutants W64A wx/wx and Sg25 o2/o2 (Table). To characterize the rate of mtRNA synthesis in mutants the ratio of absolute rate of RNA synthesis in mitochondria of spontaneous mutants to that of relative controls carrying dominant alleles of the genes was used.
Mutant Relative rate of RNA synthesis in mitochondria
  5 min 10 min 15 min 20 min
A344 sin/sin 0.60 6.54 7.26 3.87
Gb334 meg/meg 2.00 2.58 3.94 2.50
W64A wx/wx 1.36 1.48 1.03 1.32
Sg25 o2/o2 1.31 1.47 1.06 1.86

The positive correlation between the value of phenotypic effect governed by the recessive allele and relative and absolute rates of mtRNA synthesis is typical for the given set of mutants.

Yu.M. Konstantinov*, A.S. Mashnenkov, G.N. Lutsenko* and V.A. Podsosonny*

*Siberian Inst. Plant Phys. Biochem., Irkutsk

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