[Changes of flavonol and anthocyanin content during microsporogenesis]

The changes in the content of flavonols, anthocyanins, and carotenoids which can be observed in the anther during microsporogenesis were followed in Narcissus pseudonarcissus and in the Darwin tulip "Apeldoorn".The investigations revealed a distinct relationship between the process of pigmentation and the cytologic development in the anther. A marked increase in the production of flavonols occurs during and immediately after the separation of the microspores of the tetrad and seems to be connected in some specific manner with the presence of the immature pollen. In Narcissus, the total flavonol content of the anthers and their pollen and tapetum fraction reaches its highest value during the enclosure of the bud by the bulb and remains more or less unchanged until the flowers open. In contrast, an intense synthesis of flavonols does not begin in the tulip before the flower-bud has left bulb; then the flavonol content increases continuously until anthesis is reached.The colouring of the pollen by anthocyanins does not occur until the final stages of maturation.Without exceptions the production of carotenoids takes place after the separation of the microspores of the tetrad.