Meiosis in Interspecific Hybrids and Genomic Interrelationships in Guizotia Cass. (Compositae)

Abstract

Crosses were made between Guizotia abyssinica, G. scabra ssp. schimperi, G. scabra ssp. scabra, G. villosa, and G. zavatiarii. All taxa have 2n = 30. Crosses involving G. zavaltarii failed to set seed when this species was used as the male parent, but produced shrivelled seeds when it served as the female parent. In the rest of the crosses, 36% of the total number of cross-pollinated florets produced apparently well-developed seeds. 57–95% of the pollen mother cells of F1 hybrids contained 15 II at melaphase I. The mciotic abnormalities observed were univalents at mctaphase I and laggards and bridges and fragments at anaphase/telophase I and II. Two plants from crosses between G. abyssinica and G. villosa exhibited cytomixis and spontaneous fusion of pollen mother cells. The mean pollen fertility of the F, hybrids was 31–81%, and that of the parent plants was 92–96%. The results indicated that G. abyssinica and G. scabra ssp. schimperi are more closely related to each other than to the other taxa, that G. scabra ssp. scabra is more closely related to G. villosa than to G. scabra ssp. schimperi, and that G. zavaltarii has relatively low affinity to the rest of the taxa.