Wenzel C L, Williamson R E, Wasteneys G O
Plant Cell Biology Group, Research School of Biological Sciences, Australian National University, G.P.O. Box 475, Canberra, Australian Capital Territory 2601, Australia.
Plant Physiol. 2000 Oct;124(2):813-22. doi: 10.1104/pp.124.2.813.
We conducted kinematic and cytological studies on "between vein" epidermal cells of the gibberellin (GA)-deficient M489 dwarf mutant of barley (Hordeum vulgare L. Himalaya). GAs affect radial and axial components of cell expansion and cortical microtubule orientation. Adaxial cells in particular expand radially after leaving the elongation zone (EZ), probably as part of leaf unrolling. Exogenous gibberellic acid corrects the mutant's short, wide blades, short EZ, and slow elongation rate. Cell production rates increase more on the adaxial than on the abaxial surface. Cells spend equal periods of time elongating in dwarf and tall plants, but relative elemental growth rates start to decline sooner in the dwarf. GA increased the rate at which longitudinal wall area increased because the increased axial growth more than compensated for reduced radial growth. In dwarf leaves, increased radial expansion was detected in basal parts of the EZ before cortical microtubules lost transverse orientation in the distal elongation zone. We conclude that loss of microtubule orientation is not required for low GA levels to reduce growth anisotropy.
我们对大麦（Hordeum vulgare L. Himalaya）赤霉素（GA）缺乏型M489矮化突变体的“脉间”表皮细胞进行了运动学和细胞学研究。赤霉素影响细胞扩张的径向和轴向成分以及皮层微管的取向。特别是近轴细胞在离开伸长区（EZ）后径向扩张，这可能是叶片展开的一部分。外源赤霉酸可纠正突变体叶片短而宽、伸长区短以及伸长速率慢的问题。近轴表面的细胞生成速率比远轴表面增加得更多。矮化植株和高植株的细胞伸长时间相同，但矮化植株的相对元素生长速率更早开始下降。赤霉素提高了纵向壁面积增加的速率，因为轴向生长的增加超过了径向生长减少的补偿。在矮化叶片中，在伸长区基部检测到径向扩张增加，之后皮层微管在远端伸长区失去横向取向。我们得出结论，低水平的赤霉素降低生长各向异性并不需要微管取向的丧失。
