scholarly journals Exogenous melatonin enhances salt secretion from salt glands by upregulating the expression of ion transporter and vesicle transport genes in Limonium bicolor

2020 ◽  
Author(s):  
Junpeng Li ◽  
Fang Yuan ◽  
Yanlu Liu ◽  
Mingjing Zhang ◽  
Yun Liu ◽  
...  
Keyword(s):  
Salt Tolerance ◽  
Plant Growth ◽  
Transport Proteins ◽  
Vesicle Transport ◽  
Ion Transporters ◽  
Salt Glands ◽  
Exogenous Melatonin ◽  
Limonium Bicolor ◽  
Genes Encoding ◽  
Salt Secretion

Abstract Background: Salt stress inhibits plant growth and reduces yields. Melatonin is a pleiotropic molecule and can regulate plant growth and alleviate environmental stress in plants. Previous research has focused on the use of melatonin to improve the relatively low salt tolerance of glycophytes by promoting growth and enhancing antioxidant ability. It is unclear whether exogenous melatonin can increase the salt tolerance of halophytes, particularly recretohalophytes, by enhancing salt secretion from the salt glands. Results: We explored the effects of exogenous applications of melatonin on the secretion of salt from the salt glands of Limonium bicolor (a kind of recretohalophyte) seedlings and on the expression of associated genes. 5 μM exogenous melatonin significantly improved the growth of L. bicolor seedlings under 300 mM NaCl. Furthermore, exogenous melatonin significantly increased the dry weight and endogenous melatonin content of L. bicolor . In addition, this treatment reduced the content of Na + and Cl – in leaves, but increased the K + content. Both the salt secretion rate of the salt glands and the expression level of genes encoding ion transporters and vesicular transport proteins were significantly increased by exogenous melatonin treatment. These results indicate that melatonin improves the salt tolerance of the recretohalophyte L. bicolor via the upregulation of salt secretion by the salt glands. Conclusions: Our results showed that melatonin can upregulate the expression of genes encoding ion transporters and vesicle transport proteins to enhance salt secretion from the salt glands. Combining the results of the current study with previous research, we formulated a novel mechanism by which melatonin increases salt secretion in L. bicolor . Ions in mesophyll cells are transported to the salt glands through ion transporters located at the plasma membrane. After the ions enter the salt glands, they are transported to the collecting chamber adjacent to the secretory pore through vesicle transport and ions transporter and then are secreted from the secretory pore of salt glands, which maintain ionic homeostasis in the cells and alleviate NaCl-induced growth inhibition.

scholarly journals Exogenous melatonin enhances salt secretion from salt glands by upregulating the expression of ion transporter and vesicle transport genes in Limonium bicolor

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Junpeng Li ◽  
Fang Yuan ◽  
Yanlu Liu ◽  
Mingjing Zhang ◽  
Yun Liu ◽  
...  
Keyword(s):  
Salt Tolerance ◽  
Plant Growth ◽  
Environmental Stress ◽  
Transport Proteins ◽  
Vesicle Transport ◽  
Ion Transporters ◽  
Salt Glands ◽  
Exogenous Melatonin ◽  
Genes Encoding ◽  
Salt Secretion

Abstract Background Salt, a common environmental stress factor, inhibits plant growth and reduces yields. Melatonin is a pleiotropic molecule that regulates plant growth and can alleviate environmental stress in plants. All previous research on this topic has focused on the use of melatonin to improve the relatively low salt tolerance of glycophytes by promoting growth and enhancing antioxidant ability. It is unclear whether exogenous melatonin can increase the salt tolerance of halophytes, particularly recretohalophytes, by enhancing salt secretion from the salt glands. Results To examine the mechanisms of melatonin-mediated salt tolerance, we explored the effects of exogenous applications of melatonin on the secretion of salt from the salt glands of Limonium bicolor (a kind of recretohalophyte) seedlings and on the expression of associated genes. A pretreatment with 5 μM melatonin significantly improved the growth of L. bicolor seedlings under 300 mM NaCl. Furthermore, exogenous melatonin significantly increased the dry weight and endogenous melatonin content of L. bicolor. In addition, this treatment reduced the content of Na+ and Cl− in leaves, but increased the K+ content. Both the salt secretion rate of the salt glands and the expression level of genes encoding ion transporters (LbHTK1, LbSOS1, LbPMA, and LbNHX1) and vesicular transport proteins (LbVAMP721, LbVAP27, and LbVAMP12) were significantly increased by exogenous melatonin treatment. These results indicate that melatonin improves the salt tolerance of the recretohalophyte L. bicolor via the upregulation of salt secretion by the salt glands. Conclusions Our results showed that melatonin can upregulate the expression of genes encoding ion transporters and vesicle transport proteins to enhance salt secretion from the salt glands. Combining the results of the current study with previous research, we formulated a novel mechanism by which melatonin increases salt secretion in L. bicolor. Ions in mesophyll cells are transported to the salt glands through ion transporters located at the plasma membrane. After the ions enter the salt glands, they are transported to the collecting chamber adjacent to the secretory pore through vesicle transport and ions transporter and then are secreted from the secretory pore of salt glands, which maintain ionic homeostasis in the cells and alleviate NaCl-induced growth inhibition.

scholarly journals Exogenous melatonin enhances salt secretion from salt glands by upregulating the expression of ion transporter and vesicle transport genes in Limonium bicolor

2020 ◽  
Author(s):  
Junpeng Li ◽  
Fang Yuan ◽  
Yanlu Liu ◽  
Mingjing Zhang ◽  
Yun Liu ◽  
...  
Keyword(s):  
Salt Tolerance ◽  
Plant Growth ◽  
Transport Proteins ◽  
Vesicle Transport ◽  
Ion Transporters ◽  
Salt Glands ◽  
Exogenous Melatonin ◽  
Expression Of Genes ◽  
Genes Encoding ◽  
Salt Secretion

Abstract Background Salt, a common environmental stress factor, inhibits plant growth and reduces yields. Melatonin is a pleiotropic molecule that regulates plant growth and can alleviate environmental stress in plants. All previous research on this topic has focused on the use of melatonin to improve the relatively low salt tolerance of glycophytes by promoting growth and enhancing antioxidant ability. It is unclear whether exogenous melatonin can increase the salt tolerance of halophytes, particularly recretohalophytes, by enhancing salt secretion from the salt glands. Results To examine the mechanisms of melatonin-mediated salt tolerance, we explored the effects of exogenous applications of melatonin on the secretion of salt from the salt glands of Limonium bicolor (a kind of recretohalophyte) seedlings and on the expression of associated genes. A pretreatment with 5 µM melatonin significantly improved the growth of L. bicolor seedlings under 300 mM NaCl. Furthermore, exogenous melatonin significantly increased the dry weight and endogenous melatonin content of L. bicolor. In addition, this treatment reduced the content of Na+ and Cl− in leaves, but increased the K+ content. Both the salt secretion rate of the salt glands and the expression level of genes encoding ion transporters (LbHTK1, LbSOS1, LbPMA, and LbNHX1) and vesicular transport proteins (LbVAMP721, LbVAP27, and LbVAMP12) were significantly increased by exogenous melatonin treatment. These results indicate that melatonin improves the salt tolerance of the recretohalophyte L. bicolor via the upregulation of salt secretion by the salt glands. Conclusions Our results showed that melatonin can upregulate the expression of genes encoding ion transporters and vesicle transport proteins to enhance salt secretion from the salt glands. Combining the results of the current study with previous research, we formulated a novel mechanism by which melatonin increases salt secretion in L. bicolor. Melatonin binds to an unknown receptor located at the PM, which activates the downstream signaling pathway, and then a NO or ROS signaling pathway. This in turn upregulates the expression of genes encoding ion transporters and vesicle transport proteins. The ion transporters transport ions (mainly Na+) into the salt glands, which are subsequently secreted through the participation of various ion transporters and transport vesicles to maintain ionic homeostasis in the cells and alleviate NaCl-induced growth inhibition.

scholarly journals Exogenous melatonin enhances salt secretion from salt glands by upregulating the expression of ion transporter and vesicle transport genes in Limonium bicolor

2020 ◽  
Author(s):  
Junpeng Li ◽  
Fang Yuan ◽  
Yanlu Liu ◽  
Mingjing Zhang ◽  
Yun Liu ◽  
...  
Keyword(s):  
Salt Tolerance ◽  
Plant Growth ◽  
Environmental Stress ◽  
Transport Proteins ◽  
Vesicle Transport ◽  
Ion Transporters ◽  
Salt Glands ◽  
Exogenous Melatonin ◽  
Genes Encoding ◽  
Salt Secretion

Abstract Background: Salt, a common environmental stress factor, inhibits plant growth and reduces yields. Melatonin is a pleiotropic molecule that regulates plant growth and can alleviate environmental stress in plants. All previous research on this topic has focused on the use of melatonin to improve the relatively low salt tolerance of glycophytes by promoting growth and enhancing antioxidant ability. It is unclear whether exogenous melatonin can increase the salt tolerance of halophytes, particularly recretohalophytes, by enhancing salt secretion from the salt glands. Results: To examine the mechanisms of melatonin-mediated salt tolerance, we explored the effects of exogenous applications of melatonin on the secretion of salt from the salt glands of Limonium bicolor (a kind of recretohalophyte) seedlings and on the expression of associated genes. A pretreatment with 5 μM melatonin significantly improved the growth of L. bicolor seedlings under 300 mM NaCl. Furthermore, exogenous melatonin significantly increased the dry weight and endogenous melatonin content of L. bicolor. In addition, this treatment reduced the content of Na+ and Cl– in leaves, but increased the K+ content. Both the salt secretion rate of the salt glands and the expression level of genes encoding ion transporters (LbHTK1, LbSOS1, LbPMA, and LbNHX1) and vesicular transport proteins (LbVAMP721, LbVAP27, and LbVAMP12) were significantly increased by exogenous melatonin treatment. These results indicate that melatonin improves the salt tolerance of the recretohalophyte L. bicolor via the upregulation of salt secretion by the salt glands.Conclusions: Our results showed that melatonin can upregulate the expression of genes encoding ion transporters and vesicle transport proteins to enhance salt secretion from the salt glands. Combining the results of the current study with previous research, we formulated a novel mechanism by which melatonin increases salt secretion in L. bicolor. Ions in mesophyll cells are transported to the salt glands through ion transporters located at the plasma membrane. After the ions enter the salt glands, they are transported to the collecting chamber adjacent to the secretory pore through vesicle transport and ions transporter and then are secreted from the secretory pore of salt glands, which maintain ionic homeostasis in the cells and alleviate NaCl-induced growth inhibition.

scholarly journals A novel gene LbHLH from the halophyte Limonium bicolor enhances salt tolerance via reducing root hair development and enhancing osmotic resistance

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Xi Wang ◽  
Yingli Zhou ◽  
Yanyu Xu ◽  
Baoshan Wang ◽  
Fang Yuan
Keyword(s):  
Salt Tolerance ◽  
Root Hair ◽  
Salt Gland ◽  
Nacl Stress ◽  
35S Promoter ◽  
Osmotic Resistance ◽  
Salt Glands ◽  
Limonium Bicolor ◽  
Root Hair Development ◽  
Hair Development

Abstract Background Identifying genes involved in salt tolerance in the recretohalophyte Limonium bicolor could facilitate the breeding of crops with enhanced salt tolerance. Here we cloned the previously uncharacterized gene LbHLH and explored its role in salt tolerance. Results The 2,067-bp open reading frame of LbHLH encodes a 688-amino-acid protein with a typical helix-loop-helix (HLH) domain. In situ hybridization showed that LbHLH is expressed in salt glands of L. bicolor. LbHLH localizes to the nucleus, and LbHLH is highly expressed during salt gland development and in response to NaCl treatment. To further explore its function, we heterologously expressed LbHLH in Arabidopsis thaliana under the 35S promoter. The overexpression lines showed significantly increased trichome number and reduced root hair number. LbHLH might interact with GLABRA1 to influence trichome and root hair development, as revealed by yeast two-hybrid analysis. The transgenic lines showed higher germination percentages and longer roots than the wild type under NaCl treatment. Analysis of seedlings grown on medium containing sorbitol with the same osmotic pressure as 100 mM NaCl demonstrated that overexpressing LbHLH enhanced osmotic resistance. Conclusion These results indicate that LbHLH enhances salt tolerance by reducing root hair development and enhancing osmotic resistance under NaCl stress.

Methyl jasmonate improves tolerance to high salt stress in the recretohalophyte Limonium bicolor

2019 ◽  
Vol 46 (1) ◽  
pp. 82 ◽  
Author(s):  
Fang Yuan ◽  
Xue Liang ◽  
Ying Li ◽  
Shanshan Yin ◽  
Baoshan Wang
Keyword(s):  
Salt Stress ◽  
Salt Tolerance ◽  
Methyl Jasmonate ◽  
Salt Gland ◽  
Underlying Mechanism ◽  
Photosynthetic Parameters ◽  
Salt Glands ◽  
Plasma Membrane Permeability ◽  
Limonium Bicolor ◽  
Relative Electrical Conductivity

Limonium bicolor is a typical recretohalophyte with salt glands in the epidermis, which shows maximal growth at moderate salt concentrations (100mM NaCl) but reduced growth in the presence of excess salt (more than 200mM). Jasmonic acid (JA) alleviates the reduced growth of L. bicolor under salt stress; however, the underlying mechanism is unknown. In this study we investigated the effects of exogenous methyl jasmonate (MeJA) application on L. bicolor growth at high NaCl concentrations. We found that treatment with 300mM NaCl led to dramatic inhibition of seedling growth that was significantly alleviated by the application of 0.03mM MeJA, resulting in a biomass close to that of plants not subjected to salt stress. To determine the parameters that correlate with MeJA-induced salt tolerance (assessed as the biomass production in saline and control conditions), we measured 14 physiological parameters relating to ion contents, plasma membrane permeability, photosynthetic parameters, salt gland density, and salt secretion. We identified a correlation between individual indicators and salt tolerance: the most positively correlated indicator was net photosynthetic rate, and the most negatively correlated one was relative electrical conductivity. These findings provide insights into a possible mechanism underlying MeJA-mediated salt stress alleviation.

The lb23 mutant of recretohalophyte Limonium bicolor (Bag.) Kuntze with 20-, 24-, 28- and 32-cell salt glands shows elevated salt secretion

Flora ◽  
2019 ◽  
Vol 259 ◽  
pp. 151441 ◽  
Author(s):  
Bingying Leng ◽  
Xinxiu Dong ◽  
Chaoxia Lu ◽  
Kailun Li ◽  
Yanyu Xu ◽  
...  
Keyword(s):  
Salt Glands ◽  
Limonium Bicolor ◽  
Salt Secretion

scholarly journals A novel gene LbHLH from the halophyte Limonium bicolor enhances salt tolerance via alleviating osmotic stress and reducing root hair development

2021 ◽  
Author(s):  
Xi Wang ◽  
Yingli Zhou ◽  
Yanyu Xu ◽  
Baoshan Wang ◽  
Fang Yuan
Keyword(s):  
Salt Tolerance ◽  
Osmotic Stress ◽  
Root Hair ◽  
Salt Gland ◽  
Nacl Stress ◽  
35S Promoter ◽  
Salt Glands ◽  
Limonium Bicolor ◽  
Root Hair Development ◽  
Hair Development

Abstract Background Identifying genes involved in salt tolerance in the recretohalophyte Limonium bicolor could facilitate the breeding of crops with enhanced salt tolerance. Here we cloned the previously uncharacterized gene LbHLH and explored its role in salt tolerance. Results The 2,067-bp open reading frame of LbHLH encodes a 688-amino-acid protein with a typical helix-loop-helix (HLH) domain. In situ hybridization showed that LbHLH is expressed in salt glands of L. bicolor. LbHLH localizes to the nucleus, and LbHLH is highly expressed during salt gland development and in response to NaCl treatment. To further explore its function, we heterologously expressed LbHLH in Arabidopsis thaliana under the 35S promoter. The overexpression lines showed significantly increased trichome number and reduced root hair number. LbHLH might interact with GLABRA1 to influence trichome and root hair development, as revealed by yeast two-hybrid analysis. The transgenic lines showed higher germination percentages and longer roots than the wild type under NaCl treatment. Analysis of seedlings grown on medium containing mannitol with the same osmotic pressure as 100 mM NaCl or LiCl with the same ionic effect as 100 mM NaCl demonstrated that overexpressing LbHLH relieved osmotic stress. Conclusion These results indicate that LbHLH enhances salt tolerance by alleviating osmotic damage under NaCl stress.

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