大豆初生幼苗多胺氧化酶活性的细胞化学定位

Activity and Cytochemical Localization of Polyamine Oxidase in Soybean Seedlings during Early Growth

摘要:

对大豆（GZycine max（L.）Merrill）“垦农4号”萌发种子和初生幼苗中的多胺氧化酶（polyamine oxidase，PAO，EC 1.4.3.6）的活性和分布进行了研究。结果表明，PAO活性仅在种子萌发起始后（吸胀后24 h）才检测到，然后随着种子萌发进程，PAO活性快速升高。但是，在萌发种子（吸胀后72 h）和初生幼苗（吸胀后120 h）中，PAO活性在各器官中的分布有明显差异。在萌发种子中，PAO活性在胚根最高（5.17±0.91 U g^-1 FW），胚轴次之，胚芽再次之，子叶活性最低（0.12±0.03 Ug^-1 FW）；在初生幼苗中，PAO活性在下胚轴中最高（5.47±0.66Ug^-1 FW），幼根次之，顶芽再次之，子叶最低（0.10±0.03 U g^-1 FW）。这种差异对种子萌发和幼苗形态建成有积极意义。运用细胞化学定位在透射电镜下观察初生幼苗PAO在各部位的分布，发现PAO主要定位在顶芽细胞的液泡膜上、子叶细胞的细胞壁及其外侧表面、下胚轴细胞的细胞壁及其表而，且PAO与细胞壁表面结合较紧；根细胞的细胞壁、细胞间隙、细胞膜、液膜上均有分布，但以液泡膜分布居多。本研究结果进一步证实了PAO在细胞壁和细胞间隙有着较广泛的分布。首次报道PAO在细胞膜和液泡膜上有分布。

Abstract:

Activity and cytochemical localization of polyamine oxidase （PAO, EC 1.4.3.4 ） were studied in the young seedlings ofKennong 4 of Glycine max （L.） Merrill. PAO activity was undetected in the seeds until 24 h after imbibition, and increased during seed germination. However, the activity in various organs was significantly different in distribution between the germinating seeds （after 72 h of imbibition） and the young seedlings （after 120 h of imbibition）. In the germinating seeds, PAO had the highest activity in radicles （5.17±0.91 U g^-1 FW）, followed by embryonal axis, embryonic bud, and lowest in cotyledons （0.12±0.03 U g^-1 FW）. In the young seedlings, PAO showed the maximum activity in hypocotyls （5.47±0.66 U g^-1 FW）, followed by juvenile root, apical bud, and lowest in cotyledons （0.10±0.03 U g^-1 FW）. The differences of PAO activity in distribution presumably had positive effects on seed germination as well as seedling morphogenesis. PAO localization was determined in various parts of the young seedlings by using a cytochemical technique and transmission electron microscope. PAO was present mainly on vacuole membrane in apical bud cells, cell wall of both cotyledons and hypocotyls as well as on its surface. In hypocotyls, PAO closely attached to the surface of cell wall, while in root cells, it appeared in cell wall, intercellular space, on cell membrane, and especially on vacuole membrane. The results confirmed that PAO widely spread in cell wall and intercellular space. Moreover, to the author＇s best knowledge, PAO was found on cell membrane and vacuole membrane for the first time.