Center for Urban Horticulture, GF-15, University of Washington, Seattle, Washington 98195.
Plant Physiol. 1990 Apr;92(4):1021-8. doi: 10.1104/pp.92.4.1021.
This study examined the potential role of restricted phloem export, or import of substances from the roots in the leaf growth response to root hypoxia. In addition, the effects of root hypoxia on abscisic acid (ABA) and zeatin riboside (ZR) levels were measured and their effects on in vitro growth determined. Imposition of root hypoxia in the dark when transpirational water flux was minimal delayed the reduction in leaf growth until the following light period. Restriction of phloem transport by stem girdling did not eliminate the hypoxia-induced reduction in leaf growth. In vitro growth of leaf discs was inhibited in the presence of xylem sap collected from hypoxic roots, and also by millimolar ABA. Disc growth was promoted by sap from aerated roots and by 0.1 micromolar ZR. The flux of both ABA and ZR was reduced in xylem sap from hypoxic roots. Leaf ABA transiently increased twofold after 24 hours of hypoxia exposure but there were no changes in leaf cytokinin levels.
本研究探讨了限制韧皮部物质输出或从根部吸收物质在叶片对根缺氧生长反应中的潜在作用。此外，还测量了根缺氧对脱落酸（ABA）和玉米素核苷（ZR）水平的影响，并测定了它们对离体生长的影响。在黑暗中蒸腾水流最小时施加根缺氧，延迟了叶片生长的减少，直到下一个光照期。通过茎环割来限制韧皮部运输并不能消除缺氧引起的叶片生长减少。从缺氧根收集的木质部汁液存在时，叶片圆盘的离体生长受到抑制，而且在毫摩尔 ABA 存在时也受到抑制。来自通气根的汁液和 0.1 微摩尔 ZR 促进了圆盘生长。木质部汁液中 ABA 和 ZR 的通量都在缺氧根中减少。叶片 ABA 在缺氧暴露 24 小时后短暂增加了两倍，但叶片细胞分裂素水平没有变化。
