分子生物学研究技能 | 关于植物激素研究那些事？（Ethylene）（建议收藏）
结合大家感兴趣的科研问题，接着给大家介绍植物激素。本期明星是乙烯（Ethylene），也是最早研究的五种植物激素之一。不同于其他植物激素，乙烯（C2H4）是一种具有多种作用的气态植物激素。结合相关资料一块学习下（敲黑板！！！）
乙烯（Ethylene）
Phytohormones – old timers and newcomers （5+4）
The molecular structure is ethylene, C2H4. The plants show wild-type Arabidopsis exhibiting the characteristic triple response to ethylene (short with an exaggerated apical hook) and two tall etr1 mutant plants that are ethylene insensitive.
这就是大名鼎鼎的乙烯“三重反应”
Ethylene (C2H4) is a gaseous hormone with diverse actions
When germinating in the dark, impeded seedlings produce ethylene which confers a characteristic “triple response”
Ethylene synthesis
The two key enzymes, ACS and ACO, are rare and unstable
Ethylene production is primarily regulated by ACS accumulation
ACS is encoded by 9 genes and functions as a dimer
Different ACS dimers have different catalytic properties
Genetic studies identified ethylene-overproducer (eto) mutants
ETO1 is a component of a ubiquitin-ligase complex
Model of ACS regulation by ubiquitin-dependent ACS turnover
Ethylene synthesis and homeostasis – summary
Many signaling components were identified genetically
ETHYLENE RESPONSE1 (ETR1) encodes an ethylene receptor
A receptor that always shuts off signaling is dominant
Arabidopsis ethylene receptor family
Loss-of-function mutations in ethylene receptors show constitutive ethylene responses
But different receptors have different signaling strengths
Ethylene receptor mutants have also been identified in other plants
主要是在模式植物番茄上的研究！！！
The ethylene-binding domain
Mutations in the transmembrane domain abolish ethylene binding
The genetic pathway of ethylene signaling
Genetic epistasis studies determined the order of action of the genes
The receptors directly interact with CTR1 and affect its activity
CTR1 acts through EIN2, a positive regulator of ET signaling
Downstream of EIN2, a transcriptional cascade controls gene expression
Summary of ethylene synthesis and signaling
Ethylene’s effects are mediated by auxin in the root
Ethylene promotes petal senescence
Fruit ripening is induced by ethylene
Ethylene interacts with many other hormones
ETHYLENE- SUMMARY
Ongoing research
参考文献：
1. Bleecker, A. B., Estelle, M. A., Somerville, C., & Kende, H. (1988). Insensitivity to ethylene conferred by a dominant mutation in Arabidopsis thaliana. Science, 241(4869), 1086-1089.
2. Yamagami, T., Tsuchisaka, A., Yamada, K., Haddon, W.F., Harden, L.A., and Theologis, A. (2003). Biochemical diversity among the 1-amino-cyclopropane-1-carboxylate synthase isozymes encoded by the arabidopsis gene family. J. Biol. Chem. 278: 49102-49112.
3. Chang, C., Kwok, S., Bleecker, A., and Meyerowitz, E. (1993). Arabidopsis ethylene-response gene ETR1: similarity of product to two-component regulators. Science 262: 539-544.
4. Kieber, J.J., Rothenberg, M., Roman, G., Feldmann, K.A., and Ecker, J.R. (1993). CTR1, a negative regulator of the ethylene response pathway in arabidopsis, encodes a member of the Raf family of protein kinases. Cell 72: 427-441.
5. Kendrick, M.D., and Chang, C. (2008). Ethylene signaling: new levels of complexity and regulation. Curr. Opin. Plant Biol. 11: 479-485.
6. Salehin, M. and Estelle, M. (2015). Ethylene prunes translation. Cell. 163: 543-544.
7. Ju, C. and Chang, C. (2015) Mechanistic insights in ethylene perception and signal transduction. Plant Physiol. 169: 85–95.
8. Stepanova, A.N., Yun, J., Likhacheva, A.V., and Alonso, J.M. (2007). Multilevel interactions between ethylene and auxin in Arabidopsis roots. Plant Cell 19: 2169-2185.
9. Azad, A.K., Ishikawa, T., Ishikawa, T., Sawa, Y., and Shibata, H. (2008). Intracellular energy depletion triggers programmed cell death during petal senescence in tulip. J. Exp. Bot. 59: 2085-2095.
10. Barry, C.S., Llop-Tous, M.I., and Grierson, D. (2000). The regulation of 1-aminocyclopropane-1-carboxylic acid synthase gene expression during the transition from system-1 to system-2 ethylene synthesis in tomato. Plant Physiol. 123: 979-986.
11. Based on: Ju, C. and Chang, C. (2015) Mechanistic insights in ethylene perception and signal transduction. Plant Physiol. 169: 85–95.
12. Robles, L.M., Wampole, J.S., Christians, M.J., and Larsen, P.B. (2007). Arabidopsis enhanced ethylene response 4 encodes an EIN3-interacting TFIID transcription factor required for proper ethylene response, including ERF1 induction. J. Exp. Bot. 58: 2627-2639.
13. Introduction to Phytohormones, The Plant Cell, Volume 22, Issue 3, March 2010, Page 1, https://doi.org/10.1105/tpc.110.tt0310.
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