Mitochondrial sensitivity to Drechslera maydis T-toxin and the synthesis of a variant mitochondrial polypeptide in plants derived from maize tissue cultures with texas male-sterile cytoplasm.

Tissue cultures of maize carrying cms-T cytoplasm have been found to regenerate fertile, T-toxin resistant plants, with and without a selective treatment with T-toxin. Progeny of these plants were tested for mitochondrial sensitivity to T-toxin and the translation products synthesised by isolated mitochondria were analysed. The results confirm previous indications of a close correlation between susceptibility to T-toxin and the synthesis of a variant 13,000 Mr mitochondrial polypeptide. Interestingly, there appeared to be a critical level at about 33% maximum synthesis of the 13,000 Mr polypeptide above which male sterility and sensitivity to T-toxin are jointly expressed. The possibility that there is a causal link between synthesis of this additional mitochondrial polypeptide, pollen abortion and sensitivity to T-toxin is discussed.