Calcium- and salt-stress signaling in plants: Shedding light on SOS pathway

ABSTRACT The salt overly sensitive (SOS) pathway is critical for plant salt stress tolerance and has a key role in regulating ion transport under salt stress. To further investigate salt tolerance factors regulated by the SOS pathway, we expressed an N-terminal fusion of the improved tandem affinity purification tag to SOS2 (NTAP-SOS2) in sos2-2 mutant plants. Expression of NTAP-SOS2 rescued the salt tolerance defect of sos2-2 plants, indicating that the fusion protein was functional in vivo. Tandem affinity purification of NTAP-SOS2-containing protein complexes and subsequent liquid chromatography-tandem mass spectrometry analysis indicated that subunits A, B, C, E, and G of the peripheral cytoplasmic domain of the vacuolar H+-ATPase (V-ATPase) were present in a SOS2-containing protein complex. Parallel purification of samples from control and salt-stressed NTAP-SOS2/sos2-2 plants demonstrated that each of these V-ATPase subunits was more abundant in NTAP-SOS2 complexes isolated from salt-stressed plants, suggesting that the interaction may be enhanced by salt stress. Yeast two-hybrid analysis showed that SOS2 interacted directly with V-ATPase regulatory subunits B1 and B2. The importance of the SOS2 interaction with the V-ATPase was shown at the cellular level by reduced H+ transport activity of tonoplast vesicles isolated from sos2-2 cells relative to vesicles from wild-type cells. In addition, seedlings of the det3 mutant, which has reduced V-ATPase activity, were found to be severely salt sensitive. Our results suggest that regulation of V-ATPase activity is an additional key function of SOS2 in coordinating changes in ion transport during salt stress and in promoting salt tolerance.

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Pretreating poplar cuttings with low nitrogen ameliorates salt stress responses by increasing stored carbohydrates and priming stress signaling pathways

Ecotoxicology and Environmental Safety ◽

10.1016/j.ecoenv.2021.112801 ◽

2021 ◽

Vol 225 ◽

pp. 112801

Author(s):

Yongfeng Gao ◽

Yufang Sun ◽

Yongbin Ou ◽

Xinhua Zheng ◽

Qian Feng ◽

...

Keyword(s):

Salt Stress ◽

Signaling Pathways ◽

Stress Responses ◽

Stress Signaling ◽

Poplar Cuttings ◽

Low Nitrogen

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A PIP-mediated osmotic stress signaling cascade plays a positive role in the salt tolerance of sugarcane

BMC Plant Biology ◽

10.1186/s12870-021-03369-9 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Hanchen Tang ◽

Qing Yu ◽

Zhu Li ◽

Feng Liu ◽

Weihua Su ◽

...

Keyword(s):

Plasma Membrane ◽

Salt Stress ◽

Salt Tolerance ◽

Osmotic Stress ◽

Hybridization Experiment ◽

Signaling Cascade ◽

Stress Signaling ◽

Ion Leakage ◽

Positive Role ◽

Expression Levels

Abstract Background Plasma membrane intrinsic proteins (PIPs) are plant channel proteins involved in water deficit and salinity tolerance. PIPs play a major role in plant cell water balance and responses to salt stress. Although sugarcane is prone to high salt stress, there is no report on PIPs in sugarcane. Results In the present study, eight PIP family genes, termed ScPIP1–1, ScPIP1–2, ScPIP1–3, ScPIP1–4, ScPIP2–1, ScPIP2–2, ScPIP2–4 and ScPIP2–5, were obtained based on the sugarcane transcriptome database. Then, ScPIP2–1 in sugarcane was cloned and characterized. Confocal microscopy observation indicated that ScPIP2–1 was located in the plasma membrane and cytoplasm. A yeast two-hybridization experiment revealed that ScPIP2–1 does not have transcriptional activity. Real time quantitative PCR (RT-qPCR) analysis showed that ScPIP2–1 was mainly expressed in the leaf, root and bud, and its expression levels in both below- and aboveground tissues of ROC22 were up-regulated by abscisic acid (ABA), polyethylene glycol (PEG) 6000 and sodium chloride (NaCl) stresses. The chlorophyll content and ion leakage measurement suggested that ScPIP2–1 played a significant role in salt stress resistance in Nicotiana benthamiana through the transient expression test. Overexpression of ScPIP2–1 in Arabidopsis thaliana proved that this gene enhanced the salt tolerance of transgenic plants at the phenotypic (healthier state, more stable relative water content and longer root length), physiologic (more stable ion leakage, lower malondialdehyde content, higher proline content and superoxide dismutase activity) and molecular levels (higher expression levels of AtKIN2, AtP5CS1, AtP5CS2, AtDREB2, AtRD29A, AtNHX1, AtSOS1 and AtHKT1 genes and a lower expression level of the AtTRX5 gene). Conclusions This study revealed that the ScPIP2–1-mediated osmotic stress signaling cascade played a positive role in plant response to salt stress.

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