CHANGES IN PROTEIN ELECTROPHORETIC PATTERNS DURING POLLEN DEVELOPMENTIN TRADESCANTIA-BRACTEATA PLASMODIAL TAPETUM AND EFFECT OF 2,4-D APPLICATIONS

The quantitative (Biorad test) and qualitative (SDS-PAGE) variations i n total proteins at 4 successive stages of pollen development in Trade scantia bracteata tapetum were determined. Then, the effect of 2,4-D h erbicide treatments (4000 ppm and 8000 ppm) applied directly to the in florescences was analyzed. Several modifications were observed in the tapetum until the mature pollen grain stage. The presence of new polyp eptid bands affirms the occurrence of protein synthesis at late stages of pollen development. Two polypeptid bands (16 and 34 kDa) were pres ent during all stages and the high molecular weight proteins disappear ed from the tapetum at the beginning of pollen maturation. 2,4-D treat ment modified the protein patterns of Tradescantia tapetum. The 16 and 34 kDa bands were maintained after the treatments, and the appearance of a set of new bands was observed concomitantly with the disappearan ce of several polypeptidic bands: a 62 kDa protein was induced during all stages by the 8000 ppm treatment, in addition to the 74 kDa (8000 ppm) and 23 kDa (4000 ppm) bands present at the first three stages of pollen development. Some of the new bands were specific of one stage a nd one treatment. The effect of 2,4-D treatments on the tapetum is dis cussed in relation to the important role of this tissue in pollen qual ity.