Cytogenetics of Tropical Bulbous Ornamentals

I. Heterozygosity in Crinum latifolium

Abstract

Knowledge of genetic system in tropical-subtropical bulbous ornamentals is most imperative for their genetic improvement. Crinums are being studied from this aspect, and nature and extent of heterozygosity in ornamental C. latifolium has been investigated. For comparison C. asiaticum has been taken as the standard type.
Rings and/or chains involving 4, 6 or 8 chromosomes, heteromorphicity in the largest bivalent, bridge-fragment configurations are common during meiosis of the heterozygote. Some of these features are karyotypically detectable. Interlocking and entanglements appear to be the cause of interchanges. Segregation is non-disjunctional in majority of the cells, which results in total sterility.
Heterozygosity is of three types, namely interchanges, inversions and possibly a case of deficiency in the distal segment of one of the arms of one chromosome of the longest submedian pair. Because of vegetative reproduction, the heterozygote not only circumvents high level of reproductive sterility but also conserves a high level of hybridity. The latter may be of adaptive value under garden conditions.