Characterization of Amino Acid Distribution in the Floral Organs of Nicotiana tabacum

Abstract

The amino acid distribution in the floral organs of Nicotiana tabacum was studied at 2 days after anthesis an in the developmental stages of the stigma and anther. Free amino acid contents of the organs were higher than in leaves on a dry weight basis. All the organs contained a large amount of asparagine and glutamine. Asparagine was prominent in the anther and pistil, while glutamine was higher in the others. The proportion ofserine was exclusively high in the stigma and style. The calyx, floral axis and anther contained an appreciable amount of proline. Bound amino acid compositions were similar among the floral organs, although electrophoretic behaviors of the soluble protein fractions in polyacrylamide gels were different.
Protein accumulation during development was observed in both the stigma and anther. On the other hand, the co tent of free amino acids of the stigma increased during development, while that in the anther decreased at the later stages. The rapid increase of asparagine in the anther was observed 1 day before anthesis, and 6 days before in the stigma. Proline was one of the major amino acids in the anther at anthesis and its maximum concentration was observed at 3 days before anthesis. The proportion of glutamine rapidly decreased in both the stigma and anther during development.