Karyotype Alteration and Phylogeny, I

Analysis of karyotypes in Aloinae with special reference to the SAT-chromosome

Abstract

In forty-eight plants and three hybrids in Aloinae i.e., thirteen species and two varieties of Aloe, twelve species and three varieties of Gasteria, two intergeneric hybrids, fifteen species, three varieties and one interspecific hybrid of Haworthia (cf. Table 1-3), the karyotypes were analysed from the point of view of karyotype alteration. All these species except three were diploids (2n=14) and have four long and three short chromosomes in basic number. G. maculata was tetraploid (2n=28), and H. Reinwardtii and H. tesselata were hexaploids (2n=42).
Generally speaking, Aloe has the longest chromosomes and Haworthia the shortest ones. Gasteria and Haworthia have two pairs of long chromosomes with satellites (2L₁+2L₄), while Aloe has various combinations of SAT-chromosomes (cf. Table 1). These karyotypes were explicitly explained an the basis of karyotype alteration such as elimination and translocation of satellite and subsequent hybridization. Delaunay's hypothesis of “phylogenetische Chromosomenverkürzung” was discussed with special reference to the karyotypes of Museari, Ornithogalum and Aloinae.
Heitz's hypothesis of SAT-chromosomes was supported by the present analysis of karyotypes in Aloinae. The correspondence of the number of SAT-chromosomes and nucleoli in the telophase was clearly demonstrated in forty-three plant forms of Aloinae (cf. Table 1-3). The secondary constriction and the centromere were referred to in relation to the nucleolus formation.
The writer wishes to express his cordial thanks to Dr. Y. Sinotô for his helpful suggestions and criticisms in the course of this work.