Chloroplast numbers per guard cell have been determined for plant species for which the specific nuclear DNA amounts have been published by other authors. Regressions of chloroplast number on nuclear DNA amount have been calculated using species, genus, or family means, all adjusted to diploidy. All regressions are positive and significantly different from zero, showing that chloroplast number increases with increasing DNA amount. This result suggests the existence of a nucleotypic effect,i.e., an effect based on DNA amount alone, in addition to other effects.
Chloroplast reproduction Guard cells Nuclear DNA amount Nucleotype Regression