Instability of a novel multicolored flower trait in inbred and outcrossed soybean lines

Abstract

A novel, multicolored flower trait with pink and purple sectors or pink and purple flowers on the same plant was found in the soybean line LN89-5320-8-53 that was derived from stocks containing the wp allele for pink flower color. Some all purple flowered or all pink flowered lines derived from the original mutable plant were inherited in a stable manner. However, many plants that are all pink or all purple flowered do not remain stable and they switch back to other phenotypes during inbreeding. High rates of somatic instability and reversions of the wp locus were observed during self-fertilization in which the percent of plants with multicolored flowers ranged from 0.3 to 28%. In contrast to the behavior of this trait during selfing, the instability of the wp-m allele is not transmissible during outcrossing and stabilizes to the recessive pink phenotype in the F2 plants. In addition, we demonstrate that other mutable alleles for seed color (r-m) and flower color (w4-m) do not interact genetically with stable pink derivatives of the wp-m allele when combined by crossing. In addition, the mutability of the w4-m allele is also reduced in crosses to the pink line. Similarly, stable white derivatives of the w4-m locus are not activated by the wp-m mutable allele. The opposite behaviors displayed by the wp-m mutable allele during selfing and outcrossing is unusual compared to other unstable soybean alleles and to mutable alleles resulting from transposable element insertions and excisions in many plant genes. Finally, we demonstrate that novel soybean seed coat colors are produced by a pleiotropic effect of the wp/wp flower color genotype in combination with the homozygous i/i genotype for seed color and that the wp, i, and t loci segregate independently.