Analysis of Physiological Properties of Plant Dwarfism

1.以赤霉素(GA)反应的玉米矮化突变体(D5)为材料，研究了受影响的中胚轴细胞的矮化生长习性与皮质微管(MT)取向的关系。免疫荧光显微镜观察MTS的变化。表皮细胞切面(EP-t)的MT呈斜面和/或纵向排列。在d5，横向型MTS的出现频率明显低于正常。在表皮细胞的放射面(EP-r)，几乎所有的细胞都有横向定向的MT。在d5苗木中，只有少数细胞具有倾斜定向的MT。在皮层细胞(c-r)的径向表面，正常中胚轴的所有细胞都有横向定向的MTs，而在d5，GA处理24 h后，相当多的细胞的MTs呈斜/纵向取向，刺激了d5中胚轴的生长，并使EP-t、EP-r和C-r中的MTs的取向发生了横向变化。生长前期d5苗内源IAA水平低于正常苗，后期下降，与正常苗差异不显著。赤霉素对d5苗期的处理水平没有影响。生长期d5苗木半纤维素B组分含量高于正常苗，GA处理后半纤维素B组分含量降低。D5的Hb的相对分子质量分布明显高于正常。GA处理使分子量分布向低分子量区转移。

1. The relationship between the dwarf habit of growth and cortical microtubule (MT) orientation in mesocotyl cells as affected was examined using a gibberellin (GA) responding dwarf mutant of maize (d5). Mts were observed by immunofluorescence microscopy. MT arrangement in the tangential surface of epidermal cells (EP-t) was oblique and /or longitudinal. The frequency of occurrence of transversely oriented MTs is much less in d5 than normal. In the radial surface of epidermal cells (EP-r), almost all the cells had transversely oriented MTs. In d5 seedlings only a few percent of cells had obliquely oriented MTs. In the radial surface of cortex cells (c-r), all the cells of normal mesocotyls had transversely oriented MTs, while in d5, MTs in considerably a large number of cells showed oblique/longitudinal orientation By GA treatment for 24 h, the growth of d5 mesocotyls was stimulated, and the orientation of MTs in EP-t, EP-r and C-r became transverse.2. The endogenous IAA level in d5 seedlings was lower than that in normal seedlings at the early period of growth, but at later stages the level declined and no significant difference was detected between d5 and normal. GA had no effect on the level in d5 seedlings.3. The content of the hemicellulose B (HB) fraction of d5 seedlings was higher than that of normal seedings during the growth period, and GA treatment resulted in a decrease of HB. The HB of d5 showed a higher molecular-weight distribution than that of normal. GA treatment caused a shift in the distribution to the lower molecular weight range.