Negative gravitropic response of roots directs auxin flow to control root gravitropism
Negative gravitropic response of roots directs auxin flow to control root gravitropism
复制标题
根的负向地性反应引导生长素流动以控制根向地性
DOI：
10.1111/pce.13559
复制
发表时间：
2019-08-01
影响因子：
7.3
通讯作者：
Chen, Rujin
中科院分区：
文献类型：
--
作者：
Ge, Liangfa;Chen, Rujin
根尖能够感知并根据重力调整其生长方向，这种现象被称为根向地性。在此之前，我们已经证明了根系负向地性响应（NGR）是根系正向地性响应的必要条件。本研究表明，根小柱和侧根帽细胞中特异性表达的质膜蛋白NGR通过调节根小柱细胞中生长素外排载体的定位和侧根生长素在重力作用下的流动方向，控制根向地性正向反应。药理学和遗传学研究表明，ngr突变体的根向地性负响应依赖于根伸长区的极性生长素运输。细胞生物学研究进一步表明，根小柱细胞中生长素外排载体PIN3的极性定位和根尖对重力刺激的不对称侧向生长素流动在atngr1中被逆转1；3三重突变体。此外，根小柱细胞中表达的三种PIN基因同时突变会损害atngr1；3三重突变体。我们的研究揭示了NGR在根系向地性反应中的关键作用，并为根系正向向地性的早期事件和分子基础提供了新的认识。
Root tip is capable of sensing and adjusting its growth direction in response to gravity, a phenomenon known as root gravitropism. Previously, we have shown that negative gravitropic response of roots (NGR) is essential for the positive gravitropic response of roots. Here, we show that NGR, a plasma membrane protein specifically expressed in root columella and lateral root cap cells, controls the positive root gravitropic response by regulating auxin efflux carrier localization in columella cells and the direction of lateral auxin flow in response to gravity. Pharmacological and genetic studies show that the negative root gravitropic response of the ngr mutants depends on polar auxin transport in the root elongation zone. Cell biology studies further demonstrate that polar localization of the auxin efflux carrier PIN3 in root columella cells and asymmetric lateral auxin flow in the root tip in response to gravistimulation is reversed in the atngr1;2;3 triple mutant. Furthermore, simultaneous mutations of three PIN genes expressed in root columella cells impaired the negative root gravitropic response of the atngr1;2;3 triple mutant. Our work revealed a critical role of NGR in root gravitropic response and provided an insight of the early events and molecular basis of the positive root gravitropism.