Auxin Overproduction in Shoots Cannot Rescue Auxin Deficiencies in Arabidopsis Roots
Auxin Overproduction in Shoots Cannot Rescue Auxin Deficiencies in Arabidopsis Roots
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DOI：
10.1093/pcp/pcu039
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发表时间：
2014-06-01
影响因子：
4.9
通讯作者：
Zhao, Yunde
中科院分区：
文献类型：
--
作者：
Chen, Qingguo;Dai, Xinhua;Zhao, Yunde
生长素在根的发育中起着重要的作用。长期以来，人们一直认为根发育所需的生长素主要通过极性定位的生长素转运蛋白从地上部转运到根中。然而，已知生长素也在根中合成。在这里，我们证明了一组YUCCA（YUC）基因，编码生长素生物合成的限速酶，在拟南芥根发育中起着至关重要的作用。5个YUC基因（YUC 3、YUC 5、YUC 7、YUC 8和YUC 9）在根发育过程中表现出不同的表达模式。同时失活的五个YUC基因（yucQ突变体）导致非常短的和agravitropic主根的发展。通过在生长培养基中添加5 nM的天然生长素IAA或通过在yucQ的根中表达YUC基因来拯救yucQ表型。有趣的是，yucQ中芽中YUC基因的过表达导致芽中特征性的生长素过量生产表型;然而，yucQ的根缺陷没有被挽救。我们的数据表明，本地化的生长素的生物合成在根中所需的正常的根发育和生长素运输从芽是不足以支持根伸长和根向地性反应。
Auxin plays an essential role in root development. It has been a long-held dogma that auxin required for root development is mainly transported from shoots into roots by polarly localized auxin transporters. However, it is known that auxin is also synthesized in roots. Here we demonstrate that a group of YUCCA (YUC) genes, which encode the rate-limiting enzymes for auxin biosynthesis, plays an essential role in Arabidopsis root development. Five YUC genes (YUC3, YUC5, YUC7, YUC8 and YUC9) display distinct expression patterns during root development. Simultaneous inactivation of the five YUC genes (yucQ mutants) leads to the development of very short and agravitropic primary roots. The yucQ phenotypes are rescued by either adding 5 nM of the natural auxin, IAA, in the growth media or by expressing a YUC gene in the roots of yucQ. Interestingly, overexpression of a YUC gene in shoots in yucQ causes the characteristic auxin overproduction phenotypes in shoots; however, the root defects of yucQ are not rescued. Our data demonstrate that localized auxin biosynthesis in roots is required for normal root development and that auxin transported from shoots is not sufficient for supporting root elongation and root gravitropic responses.