NUCLEASE ACTIVITIES IN TRADESCANTIA-PALUDOSA AND BRASSICA-NAPUS POLLEN AND TAPETUM

In several angiosperm species, nuclease activities of tapetal origin w ere localized in the outer part of the pollen grain wall. These hydrol ytic enzymes are an obstacle to direct gene transfer into pollen and t o androgenetic transformation. The presence and the activity of nuclea ses in the male gametophyte and in the tapetum of Tradescantia paludos a (periplasmodial tapetum) and of Brassica napus (secretory tapetum) w ere assessed. Nucleases were active in Tradescantia paludosa male game tophyte and in the corresponding tapetum from the tetrad stage to the young pollen grain stage. Addition of 1 mM spermidine blocks nuclease activity in the pollen, but not in the tapetum. Nuclease activities we re also found in the pollen of Brassica napus and in the surrounding l ocular fluid but only in aged microspores and young pollen grains. Was hings removed most of the nucleases from the microspores, but only par tly from the pollen grains.