北方引种二乔木兰育苗技术及经济意义

二乔木兰(Magnolia soulangeana Soul.-Bod.)分布于我国广州、杭州、昆明等地。经引种,二乔木兰在辽宁西部(北纬41°12′～42°17′)这块高寒之地也能生长,且已开花结实并培育出引种后的子代苗木。1991年引入二乔木兰栽植成功。1995年开花,2000年该批树木结实。2005年试验播种、扦插等育苗,直到2015年才初步完成播种育苗关。9月下旬采种,种子需经低温储藏100～150天,种子6℃始萌动,催芽需20～25℃,播种25～30天出苗。二乔木兰是辽宁乃至东北少有的阔叶花卉树种,其栽培育苗成功具有重要经济价值。     

Effect of medium composition and type of vessel closure on axillary shoot production of magnolia in vitro

Proliferation of axillary shoots from nodal segments of saucer magnolia (Magnolia x soulangiana Soul.-Bod.) was achieved on modified Standardi and Catalano (S medium) and Lloyd and McCown (WPM) media containing 1.33 μmol·dm⁻³ BA and 0.54 μmol·dm⁻³ NAA. The greatest number of axillary shoots was produced on S-medium with full strength macronutrients. Statistically significant were the differences in biomass of axillary shoots cultured in vessels sealed with plastic closures. Rooting of the shoots was achieved on half strength S medium supplemented with 4.9, 9.8, 14.7 and 19.6 μmol·dm⁻³ IBA. Rooted plantlets were able to resume independent growth after a short period of acclimatization.     

The F-actin distribution during microsporogenesis in Magnolia soulangeana Soul. (Magnoliaceae)

Summary F-actin distribution during male meiosis in Magnolia soulangeana was studied by means of fluorescence microscopy following staining with rhodaminephalloidin. Actin filaments were observed to persist during all of the developmental stages of meiosis. Four main types of configurations were recognized: (1) peripheral filaments underlying the plasma membrane (cortical network); (2) filaments dispersed throughout the inner cytoplasm (central cytoplasmic network); (3) filaments associated with the meiotic spindles; (4) filaments associated with the phragmoplasts. The cortical and central cytoplasmic filaments exhibited different behaviours. Whereas the cortical network remained present in an apparently unchanged form during all of the meiotic stages, the central cytoplasmic filaments, although they never completely disappeared, were reduced and concentrated around the nucleus at the end of prophase. At metaphase, fluorescent spindles consisting of filament bundles running from pole to pole or being interrupted at the equatorial zone could be seen. At the end of both the first and second division of meiosis, fluorescent bands of filaments (disks) appeared at the level of the cell division planes (equatorial regions) where cleavage furrows were constituted. These cleavage furrows did not form when floral buds were cultivated in a cytochalasin-containing medium. Our results show that during microsporogenesis in M. soulangeana the actin filaments constitute a highly complex and dynamic system that is involved in particular in cytoplasm cleavage of the meiocytes.