蛋白酶体抑制剂MG132对青扦花粉萌发和花粉管生长的影响

EFFECTS OF MG132, AN INHIBITOR OF PROTEASOME, ON THE POLLEN GERMINATION AND TUBE GROWTH OF PECEA WILSONII

泛素/蛋白酶体系统(UPP)是真核细胞内蛋白质选择性降解的主要途径,而蛋白酶体是UPP中蛋白质降解的场所。本文应用细胞学、统计学方法以及FTIR技术研究了蛋白酶体抑制剂MG132对青扦(Peceawilsonii)花粉萌发、花粉管生长的影响。结果表明:MG132显著抑制青扦花粉萌发和花粉管生长,并导致花粉管形态异常,主要表现为花粉管亚顶端出现液泡化,并且液泡随着培养时间的延长而扩大到整个花粉管,花粉管濒临死亡;而DMSO以及非蛋白酶体抑制剂E-64不产生类似结果;半薄切片结果表明,MG132处理后不仅花粉管细胞质发生液泡化,生殖细胞也发生液泡化;FTIR分析进一步表明,MG132处理后,花粉管顶端的细胞壁蛋白和果胶质含量大幅度下降。上述结果表明:MG132通过抑制蛋白酶体活性显著影响青扦花粉萌发及花粉管生长;UPP在青扦花粉萌发、花粉管极性生长模式的建立和维持过程中起重要作用;抑制蛋白酶体活性将导致青扦花粉管的程序性死亡。

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.