Immunological Evidence of Thaumatin-Like Proteins during Tobacco Floral Differentiation

Tobacco proteins that share homology with thaumatin, a sweet protein of Thaumatococcus daniellii Benth., are produced in various physiological situations such as pathogenesis-related stress or water deficit stress. Using purified polyclonal anti-thaumatin antibodies, we have detected other thaumatin-like proteins in tobacco (Nicotiana tabacum var Samsun) that have been related with floral differentiation. Thaumatin-like proteins with apparent molecular masses of 42.6, 31.6, and 26.3 kilodaltons were found in immature and mature flower organs in vivo, and others of 46.7, 41.7, and 27.5 kilodaltons were exclusively detected in thin cell layer explants forming flowers. In situ immunolocalization revealed their synthesis in newly differentiated floral meristems, in tracheids, and in parenchyma cells.