1. Chromogenes and plasmagenes.


Since pollen sterility and chlorophyll deficient maize is conditioned by both nuclear and cytoplasmic factors it is necessary to distinguish between these two types of determiners. The terms "chromogenes" and "plasmagenes" are proposed.


Both the plasmagenes and chromogenes for pollen sterility have been combined in the same plants and are apparently independent in their action. However, there are numerous chromogenes that can restore pollen production partially when in combination with the plasmagene. In a few cases pollen production can be restored completely.


Inbreds that are commonly used in the commercial production of both field corn and sweet corn are segregating for these chromogenes that restore fertility. Therefore, these long inbred lines are not homozygous for these determiners that normally have no expression and have not been selected for or against. This is further evidence for enforced heterozygosity.


D. F. Jones