[Effects of MG132 , an inhibitor of proteasome , on the pollen germination and tube growth of Pecea wilsonii].

The ubiquitin/proteasome system is regarded as a major pathway of proteolysis in eukaryotic cells, in which the proteasome acts as primary protease for its function of degrading substrate proteins to short peptides. In the present paper, cytological, statistical studies and Fourier transform infrared (FTIR) analysis on the effects of MG132, an inhibitor of proteasome, on the pollen germination and tube growth of Pecea wilsonii were carried out in an artificial experimental system. It is showed that MG132 significantly reduced the germination rate and tube growth. Furthermore, MG132 treatment lead to vacuolization occurred both in tube cytoplasm and generative cell. While DMSO and non-proteasome inhibitor E-64 do not have similar effects. FTIR analysis revealed that MG132 treatment markedly reduced the contents of wall-bound proteins and pectin at the apex of tube. Those findings provided evidence that by inhibiting the activity of proteasme, MG132 strongly affects pollen germination and tube growth of P. wilsonii, and that UPP plays an important role in organization and maintaining polarized growth of pollen tube. Inhibition of UPP will induce apoptosis of pollen tube.