Plant Salt Tolerance: Methods and Protocols

Soil salinity is destroying several hectares of arable land every minute. Because remedial land management cannot completely solve the problem, salt tolerant crops or plant species able to remove excessive salt from the soil could contribute significantly to managing the salinity problem. The key to engineering crops for salt tolerance lies in a thorough understanding of the physiological mechanisms underlying the adaptive responses of plants to salinity. Plant Salt Tolerance: Methods and Protocols describes recent advances and techniques employed by researchers to understand the molecular and ionic basis of salinity tolerance and to investigate the mechanisms of salt stress perception and signalling in plants. With chapters written by leading international scientists, this book covers nearly 30 different methods, such as microelectrode and molecular methods, imaging techniques, as well as various biochemical assays. Written in the highly successful Methods in Molecular BiologyTM series format, chapters contain introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and notes on troubleshooting and avoiding known pitfalls. Authoritative and easily accessible, Plant Salt Tolerance: Methods and Protocols serves as an essential read for every student or researcher tackling various aspects of the salinity problem

Quantifying Kinetics of Net Ion Fluxes from Plant Tissues by Non-invasive Microelectrode Measuring MIFE Technique

International audienceNon-invasive microelectrode ion flux measuring (the MIFE system) allows concurrent quantification of net fluxes of several ions with high spatial (several ?m) and temporal (ca 5 s) resolution. Over the last 10 years, the MIFE system has been widely used to study various aspects of salt stress signaling and adaptation in plants. This chapter summarizes some major findings in the area such as using MIFE for deciphering the specific and non-specific components of salinity stress, resolving the role of the plasma membrane H(+)-pump in salinity responses, proving K(+) homeostasis as a key feature of salinity tolerance, and discovering the mechanisms behind the ameliorative effects of Ca(2+) and other mitigating factors (such as polyamines or compatible solutes). The full protocols for microelectrode fabrication, calibration, and use are then given, and two basic routines for measuring net K(+) and Na(+) fluxes from salinity stressed roots are described in the context of plant screening for salt stress tolerance

The twins K+ and Na+ in plants

In the earth's crust and in seawater, K+ and Na+ are by far the most available monovalent inorganic cations. Physico-chemically, K+ and Na+ are very similar, but K+ is widely used by plants whereas Na+ can easily reach toxic levels. Indeed, salinity is one of the major and growing threats to agricultural production. In this article, we outline the fundamental bases for the differences between Na+ and K+. We present the foundation of transporter selectivity and summarize findings on transporters of the HKT type, which are reported to transport Na+ and/or Na+ and K+, and may play a central role in Na+ utilization and detoxification in plants. Based on the structural differences in the hydration shells of K+ and Na+, and by comparison with sodium channels, we present an ad hoc mechanistic model that can account for ion permeation through HKTs

Potassium activities in cell compartments of salt-grown barley

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Correlation between net mean K efflux measured from 6-d-old wheat seedlings and final plant yield at harvest (A) and the magnitude of membrane depolarization 60 min after 80 mM NaCl application (B)

Each point represents a different cultivar.<p><b>Copyright information:</b></p><p>Taken from "A root's ability to retain K correlates with salt tolerance in wheat"</p><p></p><p>Journal of Experimental Botany 2008;59(10):2697-2706.</p><p>Published online 20 May 2008</p><p>PMCID:PMC2486465.</p><p></p

(A) The effects of 80 mM NaCl application on membrane potential in the mature zone of 6-d-old Baart 46 seedlings

(B) Steady-state membrane depolarization 60 min after salt application measured in all four cultivars. Mean ±SE (=6).<p><b>Copyright information:</b></p><p>Taken from "A root's ability to retain K correlates with salt tolerance in wheat"</p><p></p><p>Journal of Experimental Botany 2008;59(10):2697-2706.</p><p>Published online 20 May 2008</p><p>PMCID:PMC2486465.</p><p></p

Eight-week-old wheat cultivars used in this study after 6 weeks of salt treatment

The growth of salt-treated plants (shown on the left hand side of each picture) is severely restricted compared with control plants (shown on the right).<p><b>Copyright information:</b></p><p>Taken from "A root's ability to retain K correlates with salt tolerance in wheat"</p><p></p><p>Journal of Experimental Botany 2008;59(10):2697-2706.</p><p>Published online 20 May 2008</p><p>PMCID:PMC2486465.</p><p></p

(A) Net K and H flux kinetics measured in 6-d-old seedlings of Baart 46 cultivar following 80 mM NaCl treatment

Fluxes were measured in the mature zone, about 10 mm from the root tip. Means ±SE (=6). (B) Mean net K flux from each of the four cultivars over the first 60 min after NaCl application (80 mM). Means ±SE (=6). (C) Peak H efflux values measured 2 min after NaCl stress onset in four wheat cultivars. Means ±SE (=6). In all MIFE measurements, the sign convention is efflux negative.<p><b>Copyright information:</b></p><p>Taken from "A root's ability to retain K correlates with salt tolerance in wheat"</p><p></p><p>Journal of Experimental Botany 2008;59(10):2697-2706.</p><p>Published online 20 May 2008</p><p>PMCID:PMC2486465.</p><p></p