Characterization of hyperploid B-A translocations

Beckett's set of B-A translocations has been used in Neuffer's laboratory for locating recessive seedling mutants and kernel mutants to the proper chromosome arm. In general, the right B-A translocation plants can be identified by having 25% or greater pollen sterility. Proper gene markers also helped to identify the desired plants, but homozygous B-A translocations are the best. The genetic markers used included genes for anthocyanin formation, carotenoid synthesis and inviable defective kernel mutants. By having homozygous R-scm and a recessive anthocyanin gene marker in the stock, kernels that had colorless endosperm with a colored scutellum were the hyperploid B-A translocations. Genes for carotenoid formation gave white/opaque endosperm which were distinct from the yellow endosperm, and in some cases had a lethal seedling phenotype, such as vp9 (lethal embryo) or o2 (luteus seedlings), that helped to identify the hyperploids. The same discriminations were applied to all the defective kernel markers as well. In addition, most hyperploid B-A translocations have distinguishable characters, and those characters repeat again and again under different enviromental conditions. It is feasible to use those morphological characters as an indicator to identify the right hyperploids in the field. Table 1 lists the morphological characters of the B-A translocations. Genetic markers plus morphological identification insured that the right hyperploids were used in each group. Table 2 lists comparisons of certain characters of the hyperploid translocations.

Table 1.

Table 2.

M-T. Chang

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.

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