Noninvasive micromeasurement of plant salt stress

Fatty Acid Desaturases Affect Salt Tolerance in Arabidopsis
The high level of unsaturated fatty acids on plant cell membranes is an important feature, and FAD is associated with cold accumulation, heat treatment, and recently, FAD has been found to be associated with salt stress.

In January 2012, Zhang Hongxia's research group at the Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, applied non-damage microtesting technology (NMT) to the study "Arabidopsis fatty acid desaturase FAD2 is required for salt tolerance during seed germination and early seed tolerance". The research result "Arabidopsis fatty acid desaturase FAD2 is required for salt tolerance during seed germination and early seedling growth" was published in PLoS ONE, a comprehensive journal in the life sciences.

In this paper, we investigated the effect of fatty acid desaturase on salt tolerance in Arabidopsis thaliana using non-invasive microassay techniques and found that the absence of fatty acid desaturase resulted in a significant reduction in Na+ efflux from Arabidopsis roots after high salt treatment, indicating that fatty acid desaturase has an important regulatory role in transmembrane Na+/H+ transport.

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Note: The results of Na+ efflux from the root meristem of Arabidopsis thaliana. col has the largest Na+ efflux and fad2 has the smallest Na+ efflux.

Zhang JT, et al. Arabidopsis fatty acid desaturase FAD2 is required for salt tolerance during seed germination and early seedling growth. PLoS ONE, 2012, 7: e30355. (2011 IF 4.411)

Ecto-mycorrhizal fungi regulate K+/Na+ balance in poplar
Salt stress in soil is a serious environmental factor that limits agroforestry. In new biotechnological studies, ectomycorrhizal (EM) fungi were found to enhance the biomass of forest trees under salt stress, and EM promotes the growth of host plants in salt environments by increasing mineral nutrition and decreasing Na+ uptake. paxillus involutus strains MAJ and NAU are highly salt-tolerant fungi that reduce Na+ uptake and increase K+ accumulation in poplar trees. However, the relationship of how EM fungi assist plants by increasing the K+/Na+ ratio under salt stress is unclear.

In May 2012, the article "Paxillus involutus strains MAJ and NAU mediate K+/Na+ homeostasis in ectomycorrhizal Populus × canescens under NaCl stress" was published in Plant Physiology. In the paper, the ion profiles of H+, Na+, K+ and Ca2+ were measured using non-damage micro-metering technique (NMT) to investigate the mechanism by which ectomycorrhizal mycorrhizal fungi (EM) regulate the K+/Na+ homeostasis in salt-sensitive poplars and thus improve salt resistance. Na+ efflux.

This article addresses the question of the effect of ion flow profile changes on salt resistance in salt stress, and in particular, provides evidence of how EM fungi can improve host salt resistance by regulating ion flow.

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Note: K+ flow rates of poplar roots, ectomycorrhizal fungi MAJ and NAU under NaCl treatment.

Li J, et al. Paxillus involutus strains MAJ and NAU mediate K+/Na+ homeostasis in ectomycorrhizal Populus× canescens under NaCl stress. plant Physiology, 2012, 159(4): 1771-1786. (Five-Year Impact Factor: 7.016)

Double-pore K+ channel (PeTPK1) overexpression in poplar enhances salt resistance in tobacco cells
Populus is a model for studying the physiological and molecular mechanisms of salt tolerance in forest trees. Past studies have shown that the double-pore K+ (TPK) family of vesicular K+ channels plays an important role in maintaining cellular K+ homeostasis.

In 2012, Shaoliang Chen's group at Beijing Forestry University published in Plant Cell, Tissue and Organ Culture "Overexpression of a poplar two-pore K+ channel enhances salinity The article "Overexpression of a poplar two-pore K+ channel enhances salinity tolerance in tobacco cells" was published in Plant Cell, Tissue and Organ Culture, and the K+ flow rate of tobacco cells was measured using NMT. They cloned a TPK channel gene, named PeTPK, in poplar. overexpression of PeTPK1 in tobacco BY-2 cells increased salt tolerance but did not promote tolerance to hyperosmotic stress induced by mannitol (200-600 mM). after 3 weeks of NaCl (100 and 150 mM) stress treatment, transgenic cells with PeTPK1 showed higher activity and dry weight than wild-type cells. higher activity and dry weight than wild-type cells.

Salt stress caused higher Na+ accumulation and K+ loss in wild-type tobacco cells than in transgenic cells. Under short-term salt stress (100 mM NaCl, 24 h), PeTPK1 transgenic cells exhibited higher cell activity and reduced membrane permeability. The ion flow data indicated that salt stress caused altered K+ efflux. The results suggest that PeTPK1 may act as an outward K+ channel, allowing K+ influx from the vesicles into the cytoplasm, maintaining K+ homeostasis and regulating salt tolerance in poplar.

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Note: Effect of NaCl transient treatment on K+ flow rate in wild type and transgenic tobacco cells. The top panel shows the K+ flow rate of guaired cells and the bottom panel shows the K+ flow rate of protoplasts.

Wang FF, et al. Overexpression of a poplar two-pore K+ channel enhances salinity tolerance in tobacco cells. Plant Cell, Tissue and Organ Culture (PCTOC) , 2013, 112(1): 19-31. (2011 IF 3.09)

Exogenous H2O2, NO and Ca2+ regulate ion flow in two mangrove species under NaCl stress
Mangroves are salt-living plants that live in the tropics and subtropics and have both salt-secreting and non-salt-secreting species. The mechanisms of salt tolerance in mangroves involve a combination of morphological and physiological aspects. In natural saline environments, salt excretion through roots is an important mechanism for salt tolerance in plants, and maintaining a normal K+/Na+ balance in the body is very important for plants to adapt to salt stress.

In October 2012, Chen Shaoliang's group at Beijing Forestry University published in Tree Physiology, "Exogenous hydrogen peroxide, nitric oxide and calcium mediate root ion fluxes in two non-secretor mangrove species subject to salt stress. The Na+, H+, K+ and Ca2+ fluxes in the roots of non-secretor mangrove species subjected to NaCl stress were measured using NMT. Differences in the control of ion balance between mullein and autumnal eggplant were compared. It was found that high salt (400 mM NaCl) treatment for 4 weeks led to a decrease in K+/Na+ ratio in root and leaf tissues. Exogenous H2O2, NO and Ca2+ altered the Na+, K+, H+ and Ca2+ flow profiles of roots under salt stress (100 mM NaCl treatment for 24 h and 200 mM NaCl treatment for 7 days). Short-term and long-term salt stresses resulted in Na+ efflux from mullein and autumn eggplant roots, with a corresponding increase in H+ efflux and accelerated K+ efflux. Exogenous H2O2 (10 mM) treatment significantly increased Na+ efflux and limited K+ efflux from mullein roots, while CaCl2 (10 mM) reduced K+ efflux and promoted Na+ efflux from mullein. Under short-term treatment, NO treatment increased Na+ efflux, but only inhibited K+ loss in autumn eggplant.

In conclusion, NaCl induced significant Ca2+ efflux from mullein roots, and H2O2 was able to promote this efflux. Thus, salt-induced Ca2+ is beneficial in maintaining the K+/Na+ balance in mullein under high salt stress, and exogenous H2O2, NO, and Ca2+ regulate ion flow in roots of both mangrove species under NaCl stress.

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Note: Plots of the magnitude of K+ efflux from different parts of mullein and autumn eggplant roots under short- and long-term NaCl treatment and TEA treatment.

Lu YJ, et al. Exogenous hydrogen peroxide, nitric oxide and calcium mediate root ion fluxes in two non-secretor mangrove species subjected to NaCl stress . tree physiology, 2013, 33(1): 81-95. (2011 IF 2.876)

eATP regulates salt-induced signal transduction mechanisms in Populus tremula
Extracellular ATP (eATP) regulates plant growth and antioxidant defense, however, the mechanism by which eATP regulates salt tolerance is unclear.

In December 2012, Shaoliang Chen's laboratory at Beijing Forestry University published in Plos One, "Extracellular ATP signaling is mediated by H2O2 and cytosolic Ca2+ in the salt response of Populus euphratica cells", in which the mechanism of eATP on the salt response of cultured salt-tolerant woody poplar cells was analyzed using confocal, NMT (non-damaging microtest technique) and real-time quantitative PCR. Treatment of poplar cells with 200 mM NaCl induced changes in eATP levels, and the P2 receptor suramin and PPADS inhibited the effects of eATP. eATP regulates a wide range of cellular processes and is an important factor in plant adaptation to salt stress, including effects on vesicular Na+ compartmentalization, Na+/H+ exchange at the plasma membrane, K+ homeostasis, ROS regulation, salt-responsive gene expression, K+/Na+ balance, and plasma membrane repair. Furthermore, H2O2 and intracellular Ca2+ regulate eATP signaling in response to high salt in poplar cells.

The article suggests that salt-induced eATP senses salt stimulation through purinoceptors on the plasma membrane and induces downstream signals, such as H2O2 and intracellular Ca2+, which in turn alter K+/Na+ homeostasis and plasma membrane repair to maintain the activity of poplar cells themselves. The study used eATP to regulate the cellular salt resistance process and revealed the signaling mechanism of eATP, which provides a reference for improving salt resistance in other salt-sensitive trees.

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Figure Note: Effect of NaCl and ATP and inhibitors on Ca2+ flow rate.

Sun J, et al. Extracellular ATP signaling is mediated by H2O2 and cytosolic Ca2+ in the salt response of Populus euphratica cells. PLoS One, 2012, 7(12): e53136. (2011 IF 4.411)

6. New CBL kinase HbCIPK2 improves salt and drought tolerance in Arabidopsis
Salt and drought are serious threats to crop development and yield, and improving salt and drought tolerance in crops is an important way to counter this threat. Salt and drought tolerance in plants is a complex multi-gene regulated trait, and many genes are involved in this stress response. Among them, CBL protein kinases play an important role in regulating plant responses to abiotic stresses. cIPKs in the CBL family are a class of plant-specific signaling sensors, however, their precise function in stress responses is not clear.

In March 2012, Wei Jianhua's laboratory at Beijing Academy of Agricultural and Forestry Sciences published in Plant, Cell & Environment, "HbCIPK2, a novel CBL-interacting protein kinase from halophyte Hordeum brevisubulatum, confers salt and osmotic stress tolerance", reporting that HbCIPK2 is a positive regulator of salt and osmotic stress tolerance, mainly localized in the plasma membrane and nucleus. The ion flow in Arabidopsis roots was measured directly using non-damage micro-metering technique (NMT), and HbCIPK2 was found to prevent K+ loss from Arabidopsis roots and reduce Na+ accumulation in stems, maintain K+/Na+ balance and protect root cells.

This study shows that HbCIPK2 regulates the signal transduction pathway of salt stress and establishes a new mechanism for HbCIPK2 to improve salt tolerance.

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Note: Overexpression of HbCIPK2 affects the flow rate of H+ and K+ in Arabidopsis under salt stress

Li RF, et al. HbCIPK2, a novel CBL-interacting protein kinase from halophyte Hordeum brevisubulatum, confers salt and osmotic stress tolerance. plant, Cell & Environm

Noninvasive micromeasurement of plant salt stress

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