An autoradiographic study of RNA synthesis during maturation and germination of pollen grains of hyoscyamus niger

The pattern of RNA synthesis during maturation and germination of pollen grains of Hyoscyamus niger was studied using 3H-uridine autoradiography. Incorporation of label during pollen maturation was periodic with peak RNA synthesis occurring in the uninucleate, nonvacuolate pollen grains and in the vegetative cell of the bicellular pollen grains. During the early stages of germination, isotope incorporation occurred predominantly in the nucleus of the vegetative cell with little or no incorporation in the generative cell. With the appearance of the pollen tube, incorporation of 3H-uridine in the vegetative cell nucleus decreased and completely disappeared at later stages of germination. No incorporation of isotope was observed in the sperms formed in the pollen tube by the division of the generative cell. From a comparison of the results of this study with those of previous works on RNA synthesis during pollen embryogenesis in cultured anthers of H. niger, it is concluded that in contrast to embryogenic developement, there is no requirement for sustained RNA synthesis by the generative cell nucleus for normal gametophytic development. (Author)