β－葡聚糖酶的性质及其对花粉管生长的调节机理

Pollen-tube tip growth, which displays fluctuation in growth rate, is regulated by multi-factors. One of them is the property of the cell wall constructed by the networks of polysaccharides and proteins. The modification of polysaccharide structure may result in the relaxation of the tensile stress of the cell wall, and thus the cell elongation. The cell wall of pollen tube tip contains pectins and cellulose (?-D-1,4-glucan) and hemicellulose. Callose (?-D-1,3-glucan) is also the component of the cell wall of the pollen tube except the growing tip. Cell wall-bound ?-D-glucanases degradeβ-D -glucans which are major components of polysaccharides, besides pectins, in the wall. ?-D-glucanases could be expected to play a role in the regulation of pollen tube growth.Two ?-D-Glucanases were isolated from the cell wall of Lilium longiflorum Thunb. pollen tubes grown in vitro. The enzymes degrade, in an action mode of exo-enzymes, 1,3-?-D-glucan and 1,4-?-D-glucan of lily pollen tube walls. The activity of ?-D-glucanases was, in a certain extent, decreased by nojirimycin, an inhibitor of glucosidase. Tracing the growth pattern of the individual pollen tube grown in semi-solid medium by video microscopy, we demonstrated that pollen tube growth rate was strongly inhibited by nojirimycin at various concentrations. The growth inhibition brought about by nojirimycin was reversible. Our results indicated that these two exo- ?-D-glucanases play a role in the regulation of pollen germination and pollen tube growth by degrading 1,3-?-D-glucan and/or 1,4-?-D-glucan or 1,3:1,4-?-D-glucan constructed in the cell wall and thus affect the cell wall extensibilityPollen-tube tip growth, which displays fluctuation in growth rate, is regulated by multi-factors. One of them is the property of the cell wall constructed by the networks of polysaccharides and proteins. The modification of polysaccharide structure may result in the relaxation of the tensile stress of the cell wall, and thus the cell elongation. The cell wall of pollen tube tip contains pectins and cellulose (?-D-1,4-glucan) and hemicellulose. Callose (?-D-1,3-glucan) is also the component of the cell wall of the pollen tube except the growing tip. Cell wall-bound ?-D-glucanases degradeβ-D -glucans which are major components of polysaccharides, besides pectins, in the wall. ?-D-glucanases could be expected to play a role in the regulation of pollen tube growth.Two ?-D-Glucanases were isolated from the cell wall of Lilium longiflorum Thunb. pollen tubes grown in vitro. The enzymes degrade, in an action mode of exo-enzymes, 1,3-?-D-glucan and 1,4-?-D-glucan of lily pollen tube walls. The activity of ?-D-glucanases was, in a certain extent, decreased by nojirimycin, an inhibitor of glucosidase. Tracing the growth pattern of the individual pollen tube grown in semi-solid medium by video microscopy, we demonstrated that pollen tube growth rate was strongly inhibited by nojirimycin at various concentrations. The growth inhibition brought about by nojirimycin was reversible. Our results indicated that these two exo- ?-D-glucanases play a role in the regulation of pollen germination and pollen tube growth by degrading 1,3-?-D-glucan and/or 1,4-?-D-glucan or 1,3:1,4-?-D-glucan constructed in the cell wall and thus affect the cell wall extensibility

花粉管微波动式顶端生长受多因子系统调控。细胞壁多糖结构的变化导致壁的应力状态改变，调节细胞生长。壁结合的β－葡萄糖苷酶作用于β－葡萄糖苷，对花粉管生长可有调控作用。拟用生化、免疫化学和细胞学技术分离、纯化并研究百合花粉管中β－葡萄糖苷酶的结构、性质及其对花粉管生长的调节功能，为植物生殖发育机理的研究作出贡献。..