The Heterochronic Teopod1 and Teopod2 Mutations of Maize Are Expressed Non-Cell-Autonomously

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Teopod1 and Teopod2 are dominant, unlinked mutations in maize that cause dramatic morphological abnormalities, including inappropriate expression of juvenile traits in adult vegetative phytomers and the transformation of reproductive structures into vegetative ones. These phenotypes are consistent with the constitutive expression of a juvenile phase of development throughout shoot growth. To investigate the basis of the Tp1 and Tp2 phenotypes we have analyzed their cell-autonomy in mosaic Teopod:wild-type plants. Mosaic plants were generated by three different mechanisms. Tp1 has previously been shown to be non-cell-autonomous; to verify and extend these results, large wild-type sectors were generated on Tp1 plants by the spontaneous loss of a B-A translocation chromosome containing the Tp1 gene. Analysis of Tp2 cell-autonomy was complicated by a lack of useful markers on chromosome 10L proximal to Tp2. To circumvent this problem two strategies were used. A reciprocal translocation was used to link Tp2 the the wild-type allele of lw2. Sectors were induced in plants of this type by irradiation of imbibed seeds. Also, a chromosome-breaking Ds element located proximal to Tp2 was used to generate somatic sectors that uncovered w2, an albino mutation distal to Tp2. Our results demonstrate conclusively that both Tp1 and Tp2 are non-cell-autonomous. The general use of these techniques for clonal analysis in plants and the potential role of a diffusible factor in regulating the juvenile phase of development in maize are discussed.

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