Apomictic Mode Of Reproduction Research Articles

Reproductive versatility inRubus

1. Apomictic modes of reproduction were detected inRubus by combining somatic and meiotic studies with embryological studies. 2. Apospory, i.e. development from a purely vegetative embryo-sac, is the general method of non-sexual reproduction in the species examined. 3. Exceptional behaviour may occur within the sexual embryo-sac, such as (a) fusion of haploid nuclei, (b) presence of two differentiated eggs and one synergid or (c) presence of three undifferentiated nuclei at the micropylar end. 4. These abnormalities will account for the segregation of characters among asexual progeny which has been observed by Mr Crane (pp. 113, 114). 5. Comparison of the developmental processes with genetical behaviour in six polyploid species ofRubus shows that a transition from a completely sexual to completely apomictic mode of reproduction is correlated with a transition from allopolyploidy to autopolyploidy. 6. The condition determining apomixis inRubus thus seems to be sexual infertility following autopolyploidy. The work of Lidforss, in which two different pseudogamic tetraploids when crossed always yield sexually reproducing allopolyploids, agrees with this view.