Sex Chromosome Translocations in Spinacia Oleracea.

HROMOSOME 1 of Spinacia oleracea, the longest of the complement, con'tains the "alleles" X , X", and Y , that effect sex determination (ELLIS and JANICK 1960; SUTO and SUGIYAMA 1961; IIZUKA and JANICK 1962). The genotype X X is pistillate, X"X and X"X" are potentially monoecious (although X"Xm is more highly male), and X Y and X"Y are staminate. The standard chromosome 1 is heterobrachial with one arm about twice as long as the other. A homobrachial variant of this chromosome was found in accession P.I. 169671 which is due to an added segment on the short arm (BOSE and JANICK 1961). This segment appears to be a translocation from chromosome 2 and is closely linked to the sex genes (IIZUKA and JANICK 1962). The present report describes a radiation-induced translocation on the long arm of chromosome 1.