CTR1 is a key negative regulator in ethylene signal transduction. A salt-induced CTR1 like gene （TaCTR1） was cloned from wheat, its expression under abiotic stresses, subcellular localization and the effect of overe...CTR1 is a key negative regulator in ethylene signal transduction. A salt-induced CTR1 like gene （TaCTR1） was cloned from wheat, its expression under abiotic stresses, subcellular localization and the effect of overexpression of TaCTR1 on salt tolerance in tobacco was studied. A putative CTR1 gene was cloned and characterized from wheat via rapid amplification of cDNA ends （RACE） and RT-PCR. TaCTR1 expression under stresses was analyzed using semi-quantitative RT-PCR and the effect of overexpression of TaCTR1 on salt tolerance was conducted in tobacco. The full-length cDNA of TaCTR1 is 2 635 bp which codes for a polypeptide of 759 amino acids. There is a conserved serine/threonine protein kinase domain at the carboxyl terminus containing an ATP-binding site. Southern blot analysis revealed that TaCTR1 consisted of a gene family in wheat. The amino acid homologies of CTR1 among different organisms share higher similarities. Expression analysis revealed that TaCTR1 was induced by NaC1 and drought stress but inhibited by ABA treatment. Transient expression of TaCTR1-GFP in the onion epidermal cells indicated that TaCTR1 was probably targeted to the plasma membrane. Overexpression of TaCTR1 decreased salt tolerance in transgenic tobacco （Nicotiana tabacum L.） plants compared with the control. To our knowledge, TaCTR1 is the first CTR1 gene cloned in wheat and may be involved in various abiotic stresses. Overexpression of TaCTR1 decreased the salt tolerance in tobacco suggested that TaCTR1 may act as a negative regulator of salt stress in plants.展开更多
ETHYLENE INSENSITIVE2(EIN2)is a key component of ethylene signaling whose activity is inhibited upon phosphorylation of Ser^(645) and Ser^(924) by the Raf-like CONSTITUTIVE TRIPLE-RESPONSE 1(CTR1)in the absence of eth...ETHYLENE INSENSITIVE2(EIN2)is a key component of ethylene signaling whose activity is inhibited upon phosphorylation of Ser^(645) and Ser^(924) by the Raf-like CONSTITUTIVE TRIPLE-RESPONSE 1(CTR1)in the absence of ethylene.Ethylene prevents CTR1 activity and thus EIN2^(Ser645/Ser924) phosphorylation,and subcellular trafficking of a proteolytically cleaved EIN2 C terminus(EIN2-C)from the endoplasmic reticulum to the nucleus and processing bodies triggers ethylene signaling.Here,we report an unexpected complexity of EIN2-activated ethylene signaling.EIN2 activation in part requires ethylene in the absence of CTR1-mediated negative regulation.The ein2 mutant was complemented by the transgenes encoding EIN2,EIN2 variants with mutations that either prevent or mimic Ser^(645)/Ser^(924) phosphorylation,or EIN2-C;and all the transgenic lines carrying these EIN2-derived transgenes responded to ethylene.Furthermore,we found that the fluorescence protein-tagged EIN2 and its variants were affected little by ethylene and exhibited similar subcellular distribution patterns:in the cytosolic particles and nuclear speckles.Of note,the subcellular localization patterns of EIN2 proteins fused with a fluorescence protein either at the N or C terminus were similar,whereas EIN2-C-YFP was primarily observed in the cytosol but not in the nucleus.Western blots and mass spectrum analyses suggested a high complexity of EIN2,which is likely proteolytically processed into multiple fragments.Our results suggested a nuclear localization of the full-length EIN2,weak association of the EIN2^(Ser645/Ser924) phosphorylation status and ethylene signaling,and the complexity of ethylene signaling caused by EIN2 and its proteolytic products in different subcellular compartments.We propose an alternative model to explain EIN2-activated ethylene signaling.展开更多
基金supported by the National Natural Science Foundation of China (30370881, 30771348)
文摘CTR1 is a key negative regulator in ethylene signal transduction. A salt-induced CTR1 like gene （TaCTR1） was cloned from wheat, its expression under abiotic stresses, subcellular localization and the effect of overexpression of TaCTR1 on salt tolerance in tobacco was studied. A putative CTR1 gene was cloned and characterized from wheat via rapid amplification of cDNA ends （RACE） and RT-PCR. TaCTR1 expression under stresses was analyzed using semi-quantitative RT-PCR and the effect of overexpression of TaCTR1 on salt tolerance was conducted in tobacco. The full-length cDNA of TaCTR1 is 2 635 bp which codes for a polypeptide of 759 amino acids. There is a conserved serine/threonine protein kinase domain at the carboxyl terminus containing an ATP-binding site. Southern blot analysis revealed that TaCTR1 consisted of a gene family in wheat. The amino acid homologies of CTR1 among different organisms share higher similarities. Expression analysis revealed that TaCTR1 was induced by NaC1 and drought stress but inhibited by ABA treatment. Transient expression of TaCTR1-GFP in the onion epidermal cells indicated that TaCTR1 was probably targeted to the plasma membrane. Overexpression of TaCTR1 decreased salt tolerance in transgenic tobacco （Nicotiana tabacum L.） plants compared with the control. To our knowledge, TaCTR1 is the first CTR1 gene cloned in wheat and may be involved in various abiotic stresses. Overexpression of TaCTR1 decreased the salt tolerance in tobacco suggested that TaCTR1 may act as a negative regulator of salt stress in plants.
基金supported by the National Natural Science Foundation of China(31570277 and 31770302)Chinese Academy of Sciences(XDB27030208).
文摘ETHYLENE INSENSITIVE2(EIN2)is a key component of ethylene signaling whose activity is inhibited upon phosphorylation of Ser^(645) and Ser^(924) by the Raf-like CONSTITUTIVE TRIPLE-RESPONSE 1(CTR1)in the absence of ethylene.Ethylene prevents CTR1 activity and thus EIN2^(Ser645/Ser924) phosphorylation,and subcellular trafficking of a proteolytically cleaved EIN2 C terminus(EIN2-C)from the endoplasmic reticulum to the nucleus and processing bodies triggers ethylene signaling.Here,we report an unexpected complexity of EIN2-activated ethylene signaling.EIN2 activation in part requires ethylene in the absence of CTR1-mediated negative regulation.The ein2 mutant was complemented by the transgenes encoding EIN2,EIN2 variants with mutations that either prevent or mimic Ser^(645)/Ser^(924) phosphorylation,or EIN2-C;and all the transgenic lines carrying these EIN2-derived transgenes responded to ethylene.Furthermore,we found that the fluorescence protein-tagged EIN2 and its variants were affected little by ethylene and exhibited similar subcellular distribution patterns:in the cytosolic particles and nuclear speckles.Of note,the subcellular localization patterns of EIN2 proteins fused with a fluorescence protein either at the N or C terminus were similar,whereas EIN2-C-YFP was primarily observed in the cytosol but not in the nucleus.Western blots and mass spectrum analyses suggested a high complexity of EIN2,which is likely proteolytically processed into multiple fragments.Our results suggested a nuclear localization of the full-length EIN2,weak association of the EIN2^(Ser645/Ser924) phosphorylation status and ethylene signaling,and the complexity of ethylene signaling caused by EIN2 and its proteolytic products in different subcellular compartments.We propose an alternative model to explain EIN2-activated ethylene signaling.
