Effects of temperature on the mode of pollen development in anther culture of Brassica campestris

In anther culture of Brassica campestris L., the yield of pollen‐derived embryoids is greatly stimulated by a high‐temperature (35°C) tratment for the first 1 to 3 days of the culture. We have inestigated the effects of the high‐temperature treatment on the mode of pollen division in cultured anthers. Anthers containing late uninucleate pollen were cultured on modified B5 medium. High‐temperature treatment for the first 24 h inhibited the normal development of the pollen and induced abnormal symmetrical division. Which is the first step in androgenesis. This symmetrical division was rarely observed in pollen developed in vivo. In anthers cultured without high‐temperature treatment, the mode of pollen development was similar to that in vivo. This suggests that the normal differentiation of the pollen is blocked by high temperatures, and sporophtic growth is induced. Sucrose (0.29 M) was essential for the induction of this symmetrical division, though neither plant growth regulator nor any other nurient was necessary. Pollen division could not be induced effectively if sucrose was replaced by either mannitol or sorbitol plus a lower concentration of sucrose. Therefore, it seems that sucrose actively influences the embryogenic division of pollen, and does not have only an osmotic effect.