Department of Botany, University of California, Berkeley, California 94720.
Plant Physiol. 1982 Feb;69(2):323-6. doi: 10.1104/pp.69.2.323.
Auxin-induced elongation and cell wall polysaccharide metabolism were studied in excised hypocotyl sections of ponderosa pine (Pinus ponderosa) seedlings. Sections excised from hypocotyls of ponderosa pine elongate in response to the addition of auxin. The neutral sugar composition of the extracellular solution removed from hypocotyl sections by centrifugation was examined. In cell wall solution from freshly excised sections, glucose, galactose, xylose, and arabinose make up more than 90% of the neutral sugars, while rhamnose, fucose, and mannose are relatively minor components. The neutral sugar composition of the polysaccharides of the pine cell wall solution is both qualitatively and quantitatively similar to that of pea. Following auxin treatment of pine hypocotyls, the neutral sugar composition of the cell wall changes; glucose, xylose, rhamnose, and fucose increase by nearly 2-fold relative to controls in buffer without auxin. These changes in neutral sugars in response to auxin treatment are similar to those found in pea, with the exception that in pea, rhamnose levels decline in response to auxin treatment.
本研究以生长在培养基中的拟南芥幼苗为材料，研究了外源油菜素内酯对拟南芥幼苗下胚轴伸长生长的影响，发现油菜素内酯能显著促进下胚轴的伸长生长，这种促进效应能被油菜素内酯合成抑制剂 epibrassinolide 所阻断，而油菜素内酯受体突变体 bril 对油菜素内酯诱导的下胚轴伸长生长不敏感，这表明油菜素内酯是通过与其受体结合来发挥作用的。进一步研究发现，油菜素内酯能诱导下胚轴中 auxin 信号途径关键基因的表达，包括 auxin 合成基因 tirl1 和 auxin 响应基因 axr3 的表达上调，同时油菜素内酯还能促进 auxin 在下胚轴中的运输。综上所述，本研究揭示了油菜素内酯通过诱导 auxin 信号途径的激活来促进拟南芥幼苗下胚轴的伸长生长。
