杨树新梢积累营养贮藏蛋白质的细胞学研究

采用光学显微镜和电子显微镜技术，对杨树新梢中的营养贮藏蛋白质进行了细胞学鉴定。在用戊二醛固定的标本中，营养贮藏蛋白质呈颗粒状，积累在中央大液泡里。在新梢伸长生长时期，新梢茎的基部已积累了营养贮藏蛋白质，在伸长生长刚停止，中上部的叶片近成熟时，整个新梢的茎都有营养贮藏蛋白质的积累，其中，以新梢基部的茎最为丰富。营养贮藏蛋白质优先在次生韧皮部的韧皮薄壁细胞和韧皮射线薄壁细胞中积累，在新梢伸长生长停止后，新梢基部茎的木质部中也积累了相当数量的营养贮藏蛋白质，主要分布在初生木质部和内侧次生木质部的各种生活的薄壁细胞中。新梢较早地积累营养贮藏蛋白质是热带树木和温带树木的一个共同特点，对于树木的氮代谢和树木当年的生长发育可能具有重要的调控作用。

Cytological identification of vegetative storage protein in the new shoots of poplar

Vegetative storage proteins in the new shoots of poplar were identified by means of light and electron microscopy. Granular form of vegetative storage proteins was observed in the large central vacuoles of the secondary phloem parenchyma cells and secondary phloem ray parenchyma cells in the samples fixed in 4% glutaraldehyde. The accumulation of vegetative storage proteins in new shoots occurred firstly in the base parts of extending stems, and spread from the bottom to the top parts of extended stems with the most abundant vegetative storage proteins in the bottom parts. The secondary phloem parenchyma cells and secondary phloem ray parenchyma cells were the preferential sites for protein storage to the xylem parenchyma cells whereas a large amount of vegetative storage proteins was present in xylem, especially in the primary xylem and the inner secondary xylem of the extended stems. Both temperate and tropical woody plants were characterized by the early accumulation of vegetative storage proteins in new shoots, which may have a primary role in the regulation of nitrogen metabolism and the growth and development of woody plants in an annual growth cycle.