Occurrence of pollen tetrads in Aster foliaceus Lindl. (Asteraceae).

In a pollen phenotype screening performed on different Aster species (Asteraceae), a temperature-dependent mutation causing pollen tetrads was discovered in A. foliaceus. After meiosis the four microspores remain attached permanently as a tetrad and this behaviour was dependent on the temperature increase over 28°C. The persistence of callose in intersporal walls between the microspores was observed by aniline blue. Pollen tetrad was partially viable as estimated by FDA staining. Pollen tetrad was not detected in F1 interspecific hybrids thus suggesting that the mutation is recessive.