A Sweet Meet—New Mechanism on Nutrient and Hormone Regulation of Plant Growth

doi:10.11983/CBB21040

Abstract

Abstract: Continuously exposed to a variety of environmental stresses, plants need to integrate internal and external information in order to achieve the purpose of adaption to environment. Among this process the perception and regulation of the energy state and soluble sugar level are of great importance. However, the molecular mechanisms underlying the integration of sugar signaling, nutrient metabolism and stress response in plants remain unclear. Recently, a team led by Prof. Yan Xiong from Fujian Agriculture and Forestry University (FAFU) have discovered that TOR kinase, the central player in metabolic signaling pathways, can directly bind and phosphorylate the core component of ethylene signaling EIN2 protein, forming a regulatory axis to coordinate TOR and ethylene signaling. The two kinases TOR and CTR1 precisely regulates distinct phosphorylation sites on EIN2, respectively, which makes EIN2 become a coordination hub of glucose signal and ethylene signal, and precisely control plant growth and development.

Key words: glucose, ethylene, TOR, EIN2, phosphorylation

Xing Wen, Lian Jin, Hongwei Guo. A Sweet Meet—New Mechanism on Nutrient and Hormone Regulation of Plant Growth[J]. Chinese Bulletin of Botany, 2021, 56(2): 138-141.

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URL: https://www.chinbullbotany.com/EN/10.11983/CBB21040

https://www.chinbullbotany.com/EN/Y2021/V56/I2/138

Figures/Tables 1

Figure 1 The mechanism of coordinated regulation of plant growth by nutrition and ethylene signaling Protein kinases CTR1 and TOR can interact and phosphorylate EIN2, respectively, in nutrition-rich medium or ethylene- free environment. When treated with ethylene, inactivation of the receptors leads to the suppression of CTR1 and the phosphorylation levels at two serine residues (S645 and S924) of EIN2 are decreased. EIN2 is therefore cleaved and the C terminus translocates into the nucleus and/or forms P-body in the cytoplasm. Consequently, the master transcription factors EIN3/EIL1 are stabilized and the downstream gene expression is activated (Li et al. 2015; Hao et al. 2017). When nutrition deficiency occurs, TOR is inhibited and the phosphorylation level of a threonine (T657) of EIN2 is decreased, followed by the nuclear shuttling of the full-length EIN2 protein. If it occurs in darkness, EIN3/EIL1 proteins would be promoted, thus to activate the expression of downstream ERF genes and to inhibit hypocotyl elongation. Alternatively, if in light, E2Fa gene expression would be down- regulated, thus to inhibit root meristem cell proliferation. Unbroken lines indicate established interactions, broken lines indicate indirect or hypothetical interactions, arrows indicate stimulatory interactions, bar-headed lines indicate inhibitory interactions.

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