Genetic Control of Temperature‐Sensitivity of Cytoplasmic Male Sterility ( cms ) in Chives ( Allium schoenoprasum L.)

In earlier experiments with chives ( Allium schoenoprasum L.) temperature‐sensitive and temperature‐insensitive cms plants could be selected. To obtain information about the site and nature of the genetic factor(s) responsible for the temperature sensitivity of the cms, temperature‐insensitive and temperauire‐sensitive cms plants were crossed with maintainers as well as with one another. In the progenies each genotype was cloned into two clone members, and these were examined concerning their male sterility under normal (20 °C/14 °C, day/night) as well as under constantly high temperatures (24 °C/ 24 °C). The results indicate that the temperature‐sensitivity of the cms is controlled by a dominant nuclear gene “ T ”. This acts like a restorer gene at high temperatures and is ineffective at normal temperatures. Accordingly, important conclusions can be drawn with regard to the selection of temperature‐insensitive cms ‐lines as well as to the propagation of the cmi‐lines. The results are discussed in connection with the mitochondrial polypeptides probably responsible for the formation of the cms .