Phenotypic and genotypic characterization of an amylose-free starch mutant of the potato

Abstract

The amylose-free (amf) potato mutant 86.040 has been characterized phenotypically and genotypically. Not only storage starch in tubers and metabolic starch in leaves but also starch in cells with specific functions, such as columella cells in the root cap and guard cells of stomata, was amylose-free. Doubled amf-clones of 86.040 flowered well, but the percentage of stainable pollen was low (8.2%). Therefore, they were used as female parent in crosses with diploid amylose-containing plants. Over 400 pollinations gave 13 berries, all dropping off prematurely; they contained 78 ovules with embryos at different developmental stages. Twenty F1 plants were obtained by embryo rescue, all having amylose starch. Three of them were characterized more extensively. They flowered well and pollen stainabilitity as well as seed set were high. Analysis of the F1 plants and of F1 × F1 progeny plants showed that the amf-character is monogenic and recessive. The locus involved was designated amf +and the mutated allele amf.