Anther Culture in Nicotiana tabacum: The Role of the Culture Vessel Atmosphere in Pollen Embryo Induction and Growth

A comparison of four volumes of culture vessel atmosphere revealed that this variable greatly influenced the induction and growth of pollen embryos from anthers of Nicotiana tabacum. The optimum frequency of anthers producing embryos and plantlets was found with a culture atmosphere of 15 ml per anther, whereas the optimum number of plantlets was found with 5-5 ml per anther. A small volume (0-5 ml per anther) almost completely suppressed embryo induction. Removal of specific components of the culture atmosphere (ethylene, carbon dioxide, oxygen) influenced the response of the anthers but did not produce a satisfactory explanation of the inhibition of pollen embryogenesis by the small culture atmosphere volume. In particular, the influence of ethylene absorption on embryo induction and growth depended both on the culture atmosphere volume and on the stage of development of the pollen at the start of culture. Using anthers containing pollen at a stage after the first pollen grain mitosis, ethylene absorption was found to increase the survival of induced embryos. Treatment of anthers for 3 d with silver nitrate, a known antagonist of ethylene action, was not an efficient means of increasing the yield of pollen plantlets.