THE a2m(r-pa-pu) ALLELE OF THE En-CONTROLLING ELEMENT SYSTEM IN MAIZE

[摘要] The Enhancer ( En ) controlling element system in maize includes numerous alleles, one of which, a 2m(r-pa-pu), was recovered as a derivative of the a 2m(1 1511) allele. The behavior and composition of this allele is described. In the presence of the independently inherited regulatory element, En , the a 2m(r-pa-pu) allele mutates and expresses in the aleurone purple, pale and colorless sectors within a colorless background. In the absence of En , the pigmentation is uniformly pale. Colored and colorless germinal mutations of the a 2m(r-pa-pu) allele were recovered, although the derivative alleles tested did not respond to En . Uniformly colored derivatives, designated A 2', arise only from states of a 2m(r-pa-pu) that respond to an active En at relatively early stages in plant development, suggesting that somatic and germinal mutations may arise through similar events. Mutations to A 2-expressing alleles appear to occur relatively late in plant development, that is, at or near meiosis, since recognizable mutant sectors do not appear on testcross ears. Kernels exhibiting such mutants are randomly distributed over the ear. The resulting A 2' alleles express pigmentation ranging in a continual sequential series from dark pale to intense purple.

[学科分类] 医学（综合）