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

BMC Plant Biology ◽

10.1186/s12870-021-03094-3 ◽

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.

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Importin-β From the Recretohalophyte Limonium bicolor Enhances Salt Tolerance in Arabidopsis thaliana by Reducing Root Hair Development and Abscisic Acid Sensitivity

Frontiers in Plant Science ◽

10.3389/fpls.2020.582459 ◽

2021 ◽

Vol 11 ◽

Author(s):

Yanyu Xu ◽

Xiangmei Jiao ◽

Xi Wang ◽

Haonan Zhang ◽

Baoshan Wang ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Abscisic Acid ◽

Salt Tolerance ◽

Root Hair ◽

Salt Gland ◽

Physiological Parameters ◽

Limonium Bicolor ◽

Root Hair Development ◽

Aba Sensitivity ◽

Hair Development

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.

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

Functional Plant Biology ◽

10.1071/fp18120 ◽

2019 ◽

Vol 46 (1) ◽

pp. 82 ◽

Cited By ~ 12

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.

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Heterologous expression of the Limonium bicolor MYB transcription factor LbTRY in Arabidopsis thaliana increases salt sensitivity by modifying root hair development and osmotic homeostasis

Plant Science ◽

10.1016/j.plantsci.2020.110704 ◽

2021 ◽

Vol 302 ◽

pp. 110704

Author(s):

Bingying Leng ◽

Xi Wang ◽

Fang Yuan ◽

Haonan Zhang ◽

Chaoxia Lu ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Transcription Factor ◽

Heterologous Expression ◽

Root Hair ◽

Salt Sensitivity ◽

Myb Transcription Factor ◽

Limonium Bicolor ◽

Root Hair Development ◽

Osmotic Homeostasis ◽

Hair Development

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Arabidopsis ADF7 inhibits VLN1 to regulate actin filament dynamics and ROS accumulation in root hair development responses to osmotic stress

10.22541/au.161323959.99581548/v1 ◽

2021 ◽

Author(s):

Che Wang ◽

Shuangtian Bi ◽

Caiyuan Liu ◽

Mingyang Li ◽

Xiaoyu Liu ◽

...

Keyword(s):

Osmotic Stress ◽

Root Hair ◽

Actin Dynamics ◽

Actin Binding ◽

Root Tips ◽

Actin Depolymerization ◽

Root Hair Development ◽

Ros Accumulation ◽

Actin Turnover ◽

Hair Development

Actin dynamics are essential for root hair development, however, the underlying molecular mechanisms of actin binding protein cooperation and plant abiotic stress responses are largely unknown. Here, genetic analysis displayed that actin depolymerizing protein ADF7 and actin bundling protein VLN1 are positively and negatively involved in root hair development in Arabidopsis, respectively. Moreover, ADF7 acts upstream of VLN1 in root hair development by the analysis of RT-qPCR, Gus staining, Western blot and genetics. The observation of F-actin dynamics shows that ADF7 inhibits VLN1, leading to the decline of filament actin (F-actin) bundling and thick bundle formation and the increase of F-actin turnover and depolymerization in epidermal cells of root apices. Actin pharmacological experiments confirm that ADF7 and VLN1 are via regulating F-actin dynamics to active root hair development. Furthermore, F-actin depolymerization coregulated by ADF7 and VLN1 elevates the reactive oxygen species (ROS) level in root tips. Additionally, F-actin depolymerization and ROS accumulation coregulated by ADF7 and VLN1 are involved in osmotic stress-induced root hair development. Our work reveals that ADF7 inhibits VLN1 to induce F-actin turnover and depolymerization and ROS level in root tips, which play an important role in root hair formation responses to osmotic stress .

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