Cytological Studies in Cultivated Species of Camellia : I. Diploid Species and their Hybrids

Abstract

The diploid species and cultivars of Calefellia studied showed complete and normal chromosome pairing at metaphase I in meiosis. Thirteen F₁ hybrid combinations between diploid species of Camellia showed similar patterns of meiotic chr-omosome configurations and chiasma frequencies at metaphase I. These hybrid combinations showed a single chromosome configuration of 15_I_I In these hybrid combinations the chiasma frequencies deviated only slight from those of their parents. Metaphase chromosome pairing in meiosis I in hybrids of Calvzellia was not sufflcient to assign distinct genome fermulas for the properties of different chromosome sets in various s pecies. The presence of partial pollen sterility shown in many cultivated taxa of diploid Camellia was not correlated with chromosome configurations at metaphase I in PMC's. The sterility and partial sterility shown in diploid Caleeellia taxa might be due to eithel-genetic differences or cryptic structulal difEerences or chromosomal differences. Since cultivated Camellia is longeval tree or shrub and is artificially selected for economic purposes, all genetical and cytological factors discussed have been accumulated and foimed into more complicated genomic constitutions.