School of Life Sciences, Lanzhou University, Lanzhou, 730000, People's Republic of China.
Planta. 2012 Dec;236(6):1791-802. doi: 10.1007/s00425-012-1730-y. Epub 2012 Aug 14.
Ethylene and light act through specific signal transduction mechanisms to coordinate the development of higher plants. Application of 1-aminocyclopropane-1-carboxylic acid (ACC, an ethylene precursor) suppresses the hypocotyl elongation of Arabidopsis seedlings in dark, but stimulates it in light. However, the mechanisms of opposite effects of ethylene on hypocotyl elongation in light and dark remain unclear. In the present study, we investigated the key factors involved in the opposite effects of ethylene on hypocotyl elongation in Arabidopsis seedlings. The effects of ACC on hypocotyl elongation of IAA-insensitive mutants including tir1-1, axr1-3, and axr1-12 seedlings were reduced in light but not in dark. The DR5 promoter, a synthetic auxin-response promoter, was used to quantify the level of IAA responses. There was a marked increase in DR5-GFP signals in response to ACC treatment in hypocotyls of DR5-GFP seedlings in light, but not in dark. CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) is an important downstream component of light signaling. ETHYLENE-INSENSITIVE3 (EIN3, an ethylene-stabilized transcription factor) directly regulates ETHYLENE-RESPONSE-FACTOR1 (ERF1). The cop1-4 mutant treated with ACC and cop1-4/EIN3ox plants developed long hypocotyls in darkness. Expression of ERF1 in the cop1-4 mutant was induced by ACC treatment in dark, but the expression of ERF1 in the wild type was not affected. Taken together, ethylene-promoting hypocotyl via IAA is mediated by light, and COP1 has a significant impact on the transcription of some genes downstream of EIN3. Thus, COP1 plays a crucial role in the opposite effects of ethylene on hypocotyl elongation.
乙烯和光通过特定的信号转导机制协调高等植物的发育。1-氨基环丙烷-1-羧酸（ACC，乙烯前体）的应用抑制黑暗中拟南芥幼苗下胚轴的伸长，但在光照下刺激其伸长。然而，乙烯对黑暗和光照下下胚轴伸长的相反作用的机制尚不清楚。在本研究中，我们研究了参与乙烯对拟南芥幼苗下胚轴伸长的相反作用的关键因素。ACC 对包括 tir1-1、axr1-3 和 axr1-12 在内的 IAA 不敏感突变体幼苗下胚轴伸长的影响在光照下降低，但在黑暗中没有降低。DR5 启动子是一种合成的生长素反应启动子，用于定量测定 IAA 反应的水平。在光照下，DR5-GFP 幼苗的下胚轴中，DR5-GFP 信号对 ACC 处理的响应明显增加，但在黑暗中没有增加。CONSTITUTIVELY PHOTOMORPHOGENIC 1（COP1）是光信号的一个重要下游成分。ETHYLENE-INSENSITIVE3（EIN3，一种乙烯稳定的转录因子）直接调节 ETHYLENE-RESPONSE-FACTOR1（ERF1）。用 ACC 处理的 cop1-4 突变体和 cop1-4/EIN3ox 植物在黑暗中发育出长的下胚轴。在黑暗中，ACC 处理诱导 cop1-4 突变体中 ERF1 的表达，但野生型中 ERF1 的表达不受影响。总之，乙烯通过 IAA 促进下胚轴伸长是由光介导的，COP1 对 EIN3 下游某些基因的转录有显著影响。因此，COP1 在乙烯对下胚轴伸长的相反作用中起着至关重要的作用。
