The origin,identification, and cytogenetic behavior of tomato monosomics

The missing chromosomal elements were cytologically identified in a primary monosomic (haplo-11) and 18 tertiary monosomics (lacking interchanged chromosomes) induced by radiation in the tomato. For the tertiary monosomics all interchanges occurred in the centromeres, and, as with single arms deficiencies in the same materials, deficiencies are tolerated for only 15 of the 24 arms of the complement. Non-homologous pairing was frequently observed in the univalent pachytene chromosomes. The monosomic condition was not transmitted to any of the 11,981 progeny of ten tested monosomics. Reproductive fertility and gross morphology were also studied.This research was supported in part by a grant (GM 06209) from the National Institutes of Health, U.S. Public Health Service.