Complementation of isolated mitochondria from several wheat varieties.

Sarkissian (4) and Sarkissian and Srivastava (6) have pointed out a close correlation between complementation and heterosis effects with intact mitochondria isolated from wheat coleoptiles. In their experiments, mitochondria which were isolated from coleoptiles of heterozygous F1 plants show significantly higher values for 02 uptake, esterification of inorganic phosphate, and especially for respiratory control and ADP/0 ratios in comparison to those isolated from the parents. These authors (4, 6) describe further experiments in which the mitochondria isolated from the parent varieties were mixed in a suspension medium. The mixtures of parental mitochondria reached higher activities nearly to the same extent as mitochondria from hybrid plants. These were interpreted as "complementation effects." From the aspect of plant breeding, complementation of mitochondria would offer an opportunity to make an early assessment of the efficiency of heterotic combinations between two genotypes. To investigate this possibility, our studies have included the following experiments: (a) determination of heterosis in F1 hybrids of different wheat varieties; (b) complementation of mitochondria isolated from these wheat varieties for enzymic determination of phosphate esterification and polarographic determination of the respiratory control, the ADP/ 0 ratio and O consumption.