白皮松花粉发育过程中蛋白酶体活性及其分布的动态变化

Dynamic Changes in Activity and Distribution of Proteasome During Pollen Development of Pinus bungeana

蛋白酶体途径对花粉发育调控具有重要作用,但花粉发育过程中蛋白酶体的分布及其活性的动态变化一直未见报道。蛋白酶体荧光底物结合荧光分光光度计分析表明,蛋白酶体的活性从单核小孢子到具有2个原叶细胞的三细胞花粉逐渐增强,而在成熟花粉中略有下降。免疫荧光标记结合共聚焦显微镜分析表明,蛋白酶体不均匀地分布于细胞质和细胞核中,并在花粉细胞不均等分裂过程中聚集分布于先后产生的2个原叶细胞内。总之,蛋白酶体的活性及其分布在花粉发育过程中存在相关的时空动态变化,表明裸子植物花粉中的蛋白酶体活性及其分布与花粉发育具有相关性,并在原叶细胞的退化过程中起重要作用。

Although the proteasome pathway has long been considered one of the most important proteolytic systems in pollen development,the dynamic changes of proteasome activity and distribution during pollen development are largely unknown.We performed fluorogenic kinetic assays using fluorogenic substrate sLLVY-AMC to measure proteasome activity in Pinus bungeana pollen grains.Our experiment results revealed that proteasome activity increased from the uninucleate to 3-cell stage,but slightly decreased in mature pollen grains.Immunofluorescence labelling detected pro-teasome signals in the nuclei of pollen grains at all stages as well as in cytosol.Unequal distribution of proteasomes was observed in the two degradating prothallial cells.Our data indicate a link between pollen development and dynamic changes in activity and distribution of proteasome,and proteasome might take a part in the degradation of prothallial cells.