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

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.

2021 ◽  
Author(s):  
Xi Wang ◽  
Yingli Zhou ◽  
Yanyu Xu ◽  
Baoshan Wang ◽  
Fang Yuan

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.


2021 ◽  
Vol 11 ◽  
Author(s):  
Yanyu Xu ◽  
Xiangmei Jiao ◽  
Xi Wang ◽  
Haonan Zhang ◽  
Baoshan Wang ◽  
...  

AimsTo elucidate the genetics underlying salt tolerance in recretohalophytes and assess its relevance to non-halophytes, we cloned the Limonium bicolor homolog of Arabidopsis thaliana (Arabidopsis) SUPER SENSITIVE TO ABA AND DROUGHT2 (AtSAD2) and named it LbSAD2, an importin-β gene associated with trichome initiation and reduced abscisic acid (ABA) sensitivity, and then we assessed the heterologously expressed LbSAD2 in Arabidopsis.MethodsWe examined LbSAD2 expression and assessed the effect of heterologous LbSAD2 expression in Arabidopsis on root hair/trichome induction; the expression levels of possible related genes in trichome/root hair development; some physiological parameters involved in salt tolerance including germination rate, root length, and contents of Na+, proline, and malondialdehyde; and the response of ABA at the germination stage.ResultsThe LbSAD2 gene is highly expressed in the salt gland development stage and salt treatment, especially located in the salt gland by in situ hybridization, and the LbSAD2 protein contains some special domains compared with AtSAD2, which may suggest the involvement of LbSAD2 in salt tolerance. Compared with the SAD2/GL1 mutant CS65878, which lacks trichomes, CS65878-35S:LbSAD2 had higher trichome abundance but lower root hair abundance. Under 100 mM NaCl treatment, CS65878-35S:LbSAD2 showed enhanced germination and root lengths; improved physiological parameters, including high proline and low contents of Na+ and malondialdehyde; higher expression of the salt-tolerance genes Δ1-PYRROLINE-5-CARBOXYLATE SYNTHETASE 1 (P5CS1) and GST CLASS TAU 5 (GSTU5); reduced ABA sensitivity; and increased expression of the ABA signaling genes RESPONSIVE TO ABA 18 (RAB18) and SNF1-RELATED PROTEIN KINASE 2 (SRK2E), but not of the ABA biosynthesis gene 9-CIS-EPOXYCAROTENOID DIOXYGENASE 3 (NCED3).ConclusionLbSAD2 enhances salt tolerance in Arabidopsis by specifically reducing root hair development, Na+ accumulation, and ABA sensitivity.


2019 ◽  
Vol 46 (1) ◽  
pp. 82 ◽  
Author(s):  
Fang Yuan ◽  
Xue Liang ◽  
Ying Li ◽  
Shanshan Yin ◽  
Baoshan Wang

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.


2017 ◽  
Vol 29 (2) ◽  
pp. 260-276 ◽  
Author(s):  
Yan Zhu ◽  
Liang Rong ◽  
Qiang Luo ◽  
Baihui Wang ◽  
Nana Zhou ◽  
...  

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xiaojing Xu ◽  
Yingli Zhou ◽  
Ping Mi ◽  
Baoshan Wang ◽  
Fang Yuan

AbstractLimonium sinuatum, a member of Plumbaginaceae commonly known as sea lavender, is widely used as dried flower. Five L. sinuatum varieties with different flower colors (White, Blue, Pink, Yellow, and Purple) are found in saline regions and are widely cultivated in gardens. In the current study, we evaluated the salt tolerance of these varieties under 250 mmol/L NaCl (salt-tolerance threshold) treatment to identify the optimal variety suitable for planting in saline lands. After the measurement of the fresh weight (FW), dry weight (DW), contents of Na+, K+, Ca2+, Cl−, malondialdehyde (MDA), proline, soluble sugars, hydrogen peroxide (H2O2), relative water content, chlorophyll contents, net photosynthetic rate, and osmotic potential of whole plants, the salt-tolerance ability from strongest to weakest is identified as Pink, Yellow, Purple, White, and Blue. Photosynthetic rate was the most reliable and positive indicator of salt tolerance. The density of salt glands showed the greatest increase in Pink under NaCl treatment, indicating that Pink adapts to high-salt levels by enhancing salt gland formation. These results provide a theoretical basis for the large-scale planting of L. sinuatum in saline soils in the future.


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