In recent years in China, as in other countries, pollen-derived plants of maize have been obtained, from which inbred lines were also developed. After the development of the N6 medium (Chu et al., Sci. Sinica 18:659-668, 1975) for anther culture of rice, and the development of the Yu-pei medium (Ku et al., Proc. Symp. P.T.C., 35-42, 1978) for anther culture of maize, a limited amount of success was obtained for maize anther culture.
For our experiments, we used a medium constituted with the inorganic salts and organic components of Yu-pei medium, complemented with 500 mg casein hydrolysate/liter, 1 g activated charcoal/liter, 250 mg proline/liter, 120 g sucrose/liter, 8 g agar/liter, and 3 mg kinetin/liter. The pH was adjusted to 5.8 with NaOH 0.1 N before autoclaving. With the aim of obtaining embryoids without callus formation, we have not used 2,4-D in the medium.
The detached tassel and surrounding leaves were wrapped in foil and incubated at 5 C for 7 days prior to plating of anthers. After the cold treatment, the anthers were taken from the lower flower of each spikelet located on the middle of the spike. The stage of microspore development was determined using Trypan blue. The anthers were plated at about the middle uninucleate stage on petri dishes and were incubated at 28 C in darkness.
We have examined a narrow range of genotypes for their response to anther culture (Table 1). We used two floury-a and two red flint genotypes, and also anthers derived from Zea diploperennis plants. An embryoid success rate of 3% and 5% were observed in the red flint genotypes.
Our production of embryoids was poor in comparison with the results of other authors. A possible explanation rests in the fact that the anthers used in our experiments were derived from greenhouse plants. Probably, by plating anthers derived from field-grown plants the results would be improved.
Miguel Angel Rapela
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