Excised young stigma parts ofNicotiana tabacumformed style-like structures with terminal stigma-like tips. Old stigmas did not have such developmental abilities. For this proliferation, the presence of benzyladenine (BA) (over 0.1 mg/liter) in the medium was necessary. IAA (0.01-10.0 mg/liter) in combination with BA stimulated the initiation and further development of stigma-like and style-like structures. The optimal concentrations of IAA and BA in simultaneous treatment for the proliferation were 1.0 mg and 1.0 mg/liter, respectively. These organogeneses were induced both in the dark and with a photoperiod of 12 h light and 12 h dark. Tobacco pollen grains germinated on the stigma-like tips and pollen tubes penetrated into the style-like structures. Lipid analyses of these tissues revealed three fractions, i.e., a triacylglycerol, a diacylglycerol and a polar lipid fraction, each containing bothω-hydroxy fatty acids and fatty acids. This indicated that the proliferating stigma-like and style-like structures in vitro also had stigma-specific lipid compounds as in the normally grown stigmas ofN. tabacum
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