Inheritance of tuber shape in cultivated diploid potatoes

The inheritance of tuber shape was studied by developing and/or selecting clones from a cultivated diploid potato breeding program. Progeny analyses indicated that one major gene controls the round and long shapes. Round is dominant over long. The gene symbol Ro, earlier proposed by Masson, is accepted. All three possible genotypes, RoRo, Roro and roro were identified. Ro was found to be linked with I, a previously described gene which controls the expression of anthocyanin in the tuber skin. In nearly all genotypes studied the linkage was in the coupling phase; however, one parent was identified where the linkage was in the repulsion phase. The recombination frequency between Ro and I was found to be approximately 11.8%. The implication of linkage between tuber skin color and shape is discussed.