Changes in protein electrophoretic patterns during pollen development inTradescantia bracteata plasmodial tapetum and effect of 2,4-D applications

Abstract

The quantitative (Biorad test) and qualitative (SDS-PAGE) variations in total proteins at 4 successive stages of pollen development in Tradescantia bracteata tapetum were determined. Then, the effect of 2,4-D herbicide treatments (4000 ppm and 8000 ppm) applied directly to the inflorescences was analyzed. Several modifications were observed in the tapetum until the mature pollen grain stage. The presence of new polypeptid bands affirms the occurrence of protein synthesis at late stages of pollen development. Two polypeptid bands (16 and 34 kDa) were present during all stages and the high molecular weight proteins disappeared from the tapetum at the beginning of pollen maturation. 2,4-D treatment 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 disappearance 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 and one treatment. The effect of 2,4-D treatments on the tapetum is discussed in relation to the important role of this tissue in pollen quality.