Reed R C, Brady S R, Muday G K
Department of Biology, Wake Forest University, Box 7325, Winston-Salem, North Carolina 27109-7325, USA.
Plant Physiol. 1998 Dec;118(4):1369-78. doi: 10.1104/pp.118.4.1369.
In roots two distinct polar movements of auxin have been reported that may control different developmental and growth events. To test the hypothesis that auxin derived from the shoot and transported toward the root controls lateral root development, the two polarities of auxin transport were uncoupled in Arabidopsis. Local application of the auxin-transport inhibitor naphthylphthalamic acid (NPA) at the root-shoot junction decreased the number and density of lateral roots and reduced the free indoleacetic acid (IAA) levels in the root and [3H]IAA transport into the root. Application of NPA to the basal half of or at several positions along the root only reduced lateral root density in regions that were in contact with NPA or in regions apical to the site of application. Lateral root development was restored by application of IAA apical to NPA application. Lateral root development in Arabidopsis roots was also inhibited by excision of the shoot or dark growth and this inhibition was reversible by IAA. Together, these results are consistent with auxin transport from the shoot into the root controlling lateral root development.
在根中，已报道生长素存在两种不同的极性运输，这可能控制不同的发育和生长过程。为了验证源自地上部分并向根部运输的生长素控制侧根发育这一假说，在拟南芥中使生长素运输的两个极性解偶联。在根茎结合处局部施用生长素运输抑制剂萘基邻苯二甲酸（NPA），可减少侧根的数量和密度，并降低根中的游离吲哚乙酸（IAA）水平以及[3H]IAA向根中的运输。将NPA施用于根的基部一半或沿根的几个位置，仅降低了与NPA接触区域或施用部位顶端区域的侧根密度。通过在NPA施用部位顶端施用IAA可恢复侧根发育。切除地上部分或黑暗生长也会抑制拟南芥根中的侧根发育，而这种抑制可通过IAA逆转。这些结果共同表明，生长素从地上部分运输到根部控制着侧根发育。
