Ten mutant alleles at the C locus: complementation potential

It is believed that two different alleles which otherwise lack the potential to produce color by themselves, might complement each other and will be able to produce color in the aleurone tissue of maize. According to this proposal for complementation, each of these two different alleles would be expected to produce a partial transcript because of the placement of the transposable element insert in their exons, which thereby would contribute to the production of a complete gene product.

In the present study 10 different mutable alleles at the C locus were used. Nine have either En or I of the En system and the tenth has the ruq of the Uq system. The alleles are c-m611702, c-m641963, c-m655208, c-m655292, c-m655320, c-m641936, c-m655437, c-m655370, c-m641905 (all En mutants) and c-m816666 (Uq system). All have a spotted phenotype in a null (colorless) background. (Other c-mutable alleles which have the same phenotype but do develop color during germination, in the light, have not been included in the diallelic crosses because the present study was aimed at observing whether there is any color development and thus complementation).

Kernels of the above ten c-mutable alleles were crossed to each other to create 45 different diallelic combinations (Figure 1). Approximately 20 kernels from each of these combinations have been germinated under light to observe color development in the aleurone. Very little color developed. Only 15 kernels developed a light color while the rest were without color. Further studies are in progress to confirm the above observations.

Figure 1. Color development in developing seedlings among 10 mutable alleles in a diallel series. A, B, C, etc. represent the different alleles.

Ch. Jayaram and Peter A. Peterson


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