Strigolactones' Effect on Root Growth and Root-Hair Elongation May Be Mediated by Auxin-Efflux Carriers
Strigolactones' Effect on Root Growth and Root-Hair Elongation May Be Mediated by Auxin-Efflux Carriers
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DOI：
10.1007/s00344-009-9122-7
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发表时间：
2010-06-01
影响因子：
4.8
通讯作者：
Kapulnik, Yoram
中科院分区：
文献类型：
--
作者：
Koltai, Hinanit;Dor, Evgenia;Kapulnik, Yoram
独脚金内酯是一类新的植物激素，在植物的地上结构调控中起着关键作用。然而，它们调控植物生长发育的机制尚不清楚。我们描述了合成的独角曲内酯（GR24）对番茄（Solanum lycopersicon）根系的影响，并提出了它与植物激素生长素的关系的证据。我们证明了独角甾内酯干扰外源施加的生长素对根伸长的抑制作用。gr24诱导的根伸长是通过根细胞长度的增加和细胞直径的减少来传递的，尽管孤孤内酯减少了细胞分裂（检测为CYCB1；1转录物的减少）。此外，高浓度的独角麦内酯导致根系生长不对称，抑制根毛伸长。外源施用NAA或IAA均不能恢复独角麦内酯存在下的对称根生长和根毛伸长。然而，应用生长素外排抑制剂NPA，在独角麦内酯存在下确实恢复了根毛伸长。同样，外源应用2,4- d（一种不由外排载体分泌的合成生长素），在独角麦内酯存在的情况下恢复根毛伸长和对称生长。然而，2,4- d不能阻止独角酯内酯的根伸长。因此，独角甾内酯对根生长和根毛伸长的影响似乎是通过对生长素外排载体的影响来介导的。然而，控制独脚金内酯对根生长影响的机制可能不止一种。
Strigolactones are a new group of plant hormones that play a pivotal role in the regulation of aboveground plant architecture. However, the mechanisms governing their regulation of plant growth and development are unknown. We characterized the effect of a synthetic strigolactone (GR24) on tomato (Solanum lycopersicon) roots and present evidence for its relationship with the plant hormone auxin. We demonstrate that strigolactones interfere with the inhibitory effect of exogenously applied auxin on root elongation. This GR24-induced root elongation is conveyed via an increase in root cell length accompanied by a reduction in cell diameter, and it occurs despite strigolactone's reduction of cell division (detected as reduction of CYCB1;1 transcript). In addition, high concentrations of strigolactone lead to asymmetric root growth and inhibition of root-hair elongation. Exogenous application of NAA or IAA was unable to restore symmetric root growth and root-hair elongation in the presence of strigolactone. However, application of NPA, an auxin-efflux inhibitor, did restore root-hair elongation in the presence of strigolactone. Similarly, exogenous application of 2,4-D, a synthetic auxin that is not secreted by efflux carriers, restored root-hair elongation and symmetric growth in the presence of strigolactone. Nevertheless, 2,4-D was unable to prevent root elongation by strigolactones. Therefore, strigolactones' effect on root growth and root-hair elongation appears to be mediated via an effect on auxin-efflux carriers. Nevertheless, more than one mechanism may govern strigolactones' effect on root growth.