Abstract:

In order to explore the reason why there is no fruit in autumn despite of thousands of flowers of ‘Kushui’ rose（Rosa sertate × R. rugosa Yu. et. Ku.） blossoming in garden， we conducted a genetic research on its cross fertility in this study. The results showed that the selfing of ‘Kushui’ rose did not bear fruit in nature or by artificial pollination. Meanwhile， there were no fruit obtained once pollen of ‘Kushui’ rose being pollinated on the stigmas of the other varieties in Rosa. In contrast to this， ‘Kushui’ rose could produce amount of seeds when pollinated with pollen from the same other materials. All evidences supported that the pollen of ‘Kushui’ rose rose was sterile. Further， several reproductive features， such as stamen petallization， P/O value， pollen heteromorphorsis， and pollen germination rate were studied， with the results showing the pollen of ‘Kushui’ rose deformed so seriously that the germination rate was nearly zero. Furthermore， microscopic observation of pollen mother cells at different phases of meiosis revealed there were so much abnormal behaviors of chromosome allocation as well as unequal cytokinesis that plenty of triads were yielded that coexisting with deformed tetrad in pollen sac. In conclusion， the study shows that the abnormal division of pollen mother cells of ‘Kushui’ rose is responsible for the pollen sterility and no fruit setting when used as paternal parent in hybridization. And that pollen abortion causing male sterile， rather than self-incompatibility commonly distributing in Rosaceae， is responsible for the intraspecific cross infertility of ‘Kushui’ rose， further implying it is feasible to improve its germplasm by acting as a maternal in cross-breeding.

Key words: ‘Kushui’ rose, pollen abortion, male sterility, meiosis, cross fertility