摘要
南瓜(Cucurbita moschata Duch.)花粉离体萌发过程中,由于壁蛋白及胞质中部分蛋白质的释放,蛋白质含量有所下降。萌发过程中具有 RNA 及蛋白质合成活力,RNA 合成活力随培养时间延长而下降,其大部分的合成活力可被α-鹅膏蕈碱所抑制。蛋白质的合成量随萌发时间延长而增加,合成活力几乎完全被亚胺环己酮抑制,为α-鹅膏蕈碱部分抑制,说明贮藏mRNA 与新合成 mRNA 共同指导蛋白质的新合成。离体条件下,亚胺环己酮和α-鹅膏蕈碱抑制花粉管的生长。在整体条件下,亚胺环己酮抑制花粉萌发与花粉管生长,说明蛋白质和RNA 的新合成对花粉管的持续生长是必需的。
The total protein content of squash(Cucurbita moschata Duch.)pollen decreased gradn- ally during in vitro germination.It was cansed by the release of wall proteins and part of the cytoplasmic proteins.The release of the pollen wall proteins was not dependent on get- mination,it was a passive diffusion process.However,the cytoplasmic proteins did not rele- ase until the pollen germinated,a fraction of them was synthesized de novo during germina- tion. The RNA and protein synthetic activities initiated soon after in vitro pollen germina- tion.The RNA synthesis decreased during germination.As about half the activity was in- hibited by α-amanitin,mRNA might be the major RNA synthesized dc novo.The total pro- tein synthesis increased during germination,almost all of this synthesis was inhibited by cyc- loheximide,and partially by α-amanitin,but it was not affected significantly by actinomycin D.These results indicated that both stored and dc novo synthesized mRNA might play a role in the protein synthesis.The content of stored mRNA of squash pollen was about 11.3 pg/grain as measured by UV absorption after its purification from total RNA(2440 pg/grain) by oligo(dT)-cellulose affinity chromatagraphy. Both cycloheximide and α-amanitin inhibited pollen tube growth in vitro.Actinomycin D and tunicamycin inhibited pollen germination in the first hour,however,no reduction of the tube length was observed later.Cycloheximide inhibited the pollen germination and tube elongation in vivo,that fitted well with the in vitro results.According to these results,it was suggested that the de novo syntheses of mRNA and protein were neccessary for the ma- intenance of pollen tube growth.
