CYTOLOGICAL AND GENETICAL IDENTIFICATION OF THE PRIMARY TRISOMICS OF THE TOMATO

Abstract

HE pioneer investigations of the prime types of Datura by BLAKESLEE T and BELLING (1924) have stimulated similar studies in an ever increasing number of plant species. Primary trisomics perform the useful service of identifying the chromosomes with their respective linkage groups as a result of the modifying by extra chromosomes of genetic ratios. Similar identifications followed shortly in Datura: the gene " White " was identified with the trisomic type " Poinsettia " ( BLAKESLEE and FARNHAM 1923) ; " Swollen " with " Ilex " In Zea extensive data were presented ( MCCLIN-TOCK 1929; MCCLINTOCK and HILL 1931) to prove the location of r on the smallest chromosome of the haploid set, and it was mentioned that associations between trisomics and five other linkage groups had been found. It was indicated later by EMERSON, BEADLE and FRASER (1935) that MCCLINTOCK and BURNHAM had identified nine linkage groups with their respective chromosomes in maize by using the trisomic method.