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If anthers of Datura innoxia containing microspores are cultured at 28° C for 24 h, two forms of haploid pollen grains are produced; one with typical unequal generative and vegetative nuclei (A), and the other with equal vegetativetype nuclei (B). The A form predominates. After 24 to 72 h in culture, three embryogenic events ensue; 1) division of the vegetative cell in A grains accompanied by rapid degeneration of the generative cell, 2) simultaneous or independent mitosis of the nuclei in B grains, and 3) simultaneous mitosis of both the generative and vegetative nuclei in A grains following two successive cycles of DNA synthesis in the generative nucleus, but only one in the vegetative nucleus (C). The endoreduplicated generative nucleus gives rise to diplochromosomes which it is postulated divide on a common spindle together with the vegetative chromosomes to yield a 3n proembryoid. In other C grains, simultaneous mitosis of an endoreduplicated generative nucleus and two vegetative daughter nuclei can occur. Nuclear fusion in these grains is envisaged as leading to a 4n proembryoid. Diploid proembryoids probably arise by nuclear fusion in A or B grains. At plantlet emergence, mainly n and 2n plantlets are obtained. Higher ploidy proembryoids fail to develop probably as a result of competitive influences.Similar embryogenic events occur in cultures initiated at the stages of the first pollen mitosis and young pollen grains, but C embryogenesis predominates. Competition from lower ploidy embryoids is minimised and 3n, 4n and even 6n plantlets are obtained.

Embryoid formation was induced in pollen of Solanum tuberosum, cv . Pentland Crown, Maris Piper and Record, by culturing anthers at or just prior to the first pollen mitosis . The composition of the medium was not critical in respect of either nutrients or hormones . In the presence of relatively high hormone levels, callus formation also occurred from somatic tissues of the anthers .

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Anther culture of Sorghum bicolor (L.) Moench I. Effect of panicle pretreatment, anther incubation temperature and 2,4-D concentration 15 Abstract. In a study of anther culture in Sorghum bicolor it was found that culture incubation temperature had a significant effect on yields of microspore-derived callus. A temperature of 33°C was superior to 25 °, 28 ° or 37 ° C. With fresh, unpretreated material, callus was produced only from anthers incubated at 33 ° C.Panicle pretreatment at 7 ° , 14 ° , 20 ° , 25 ° or 28 ° C either had no effect or significantly decreased callus yield.Comparison of culture media containing a range of concentrations of 2,4-dichlorophenoxyacetic acid (0-3.0 mg 1-1) showed that callus yield increased significantly with concentration up to 2.5 mg1-1 and then declined slightly. Although 1174 calluses were produced, subsequent differentiation was poor and only four albino plants were regenerated.