journal of biological science and bioconservation 01/2012; 4:47-53.


The study on ion homeostasis and cytotoxic ion sequestration in tomato (Solanum lycospersicum L.) was investigated. Salinity stress did not show a significant effect (P>0.05) on dry matter accumulation of shoots and roots of tomato. The accumulation of sodium ion (Na +) in root of tomato increased in salt treated groups (50 mM, 75 mM and 100 mM) while in shoot of tomato, the Na + accumulation was highest (6 times higher than the control) in 75 mM treatment. Potassium (K +) uptake was salt concentration dependent in both shoot and root and 50 mM treatment of each organ yielded highest K + content. The Na + /K + levels in shoot and root increased with increasing concentrations but the magnitude of this level is lower in shoot than in root due to the high level of K + content in the shoot tissues. It can be concluded from these findings that Na + was compartmentalised both in shoot and root of tomato by membrane transporters and that low level of Na + /K + level was a good indicator of salt tolerance property in the tomato genotype studied. INTRODUCTION Salinity stress is a major constraint to food production because it limits crop yield and restrict the use of land previously uncultivated. Salinity affects plants through hyper

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Available from: Abubakar Mohammad gumi, Oct 05, 2015
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    ABSTRACT: Plant responses to salinity stress are reviewed with emphasis on molecular mechanisms of signal transduction and on the physiological consequences of altered gene expression that affect biochemical reactions downstream of stress sensing. We make extensive use of comparisons with model organisms, halophytic plants, and yeast, which provide a paradigm for many responses to salinity exhibited by stress-sensitive plants. Among biochemical responses, we emphasize osmolyte biosynthesis and function, water flux control, and membrane transport of ions for maintenance and re-establishment of homeostasis. The advances in understanding the effectiveness of stress responses, and distinctions between pathology and adaptive advantage, are increasingly based on transgenic plant and mutant analyses, in particular the analysis of Arabidopsis mutants defective in elements of stress signal transduction pathways. We summarize evidence for plant stress signaling systems, some of which have components analogous to those that regulate osmotic stress responses of yeast. There is evidence also of signaling cascades that are not known to exist in the unicellular eukaryote, some that presumably function in intercellular coordination or regulation of effector genes in a cell-/tissue-specific context required for tolerance of plants. A complex set of stress-responsive transcription factors is emerging. The imminent availability of genomic DNA sequences and global and cell-specific transcript expression data, combined with determinant identification based on gain- and loss-of-function molecular genetics, will provide the infrastructure for functional physiological dissection of salt tolerance determinants in an organismal context. Furthermore, protein interaction analysis and evaluation of allelism, additivity, and epistasis allow determination of ordered relationships between stress signaling components. Finally, genetic activation and suppression screens will lead inevitably to an understanding of the interrelationships of the multiple signaling systems that control stress-adaptive responses in plants.
    Annual Review of Plant Biology 07/2000; 51:463-499. DOI:10.1146/annurev.arplant.51.1.463 · 18.71 Impact Factor
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    ABSTRACT: This chapter discusses the potassium estimation, uptake, and its role in the physiology and metabolism of flowering plants. Potassium is one of the vital elements involved in inorganic plant nutrition. A number of methods have been developed for the qualitative and quantitative estimation of potassium. It is now feasible to determine accurately K+ content even at the cellular level. Two methods are available for the quantitative estimation of K+ in situ: electron probe X-ray microanalysis and potassium-sensitive microelectrodes. Electron probe X-ray microanalysis permits the simultaneous quantitative estimation of several elements in a microstructure. In principle, an electron beam is focused on a section of tissue that excites atoms to emit X-rays whose energy is characteristic of the elements. The X-rays are collected in a tune spectrometer, converted to electrical pulses, and counted. Electron probe X-ray microanalysis can also be used for qualitative localization of ions, a technique called X-ray mapping. The chapter reveals that potassium uptake is mainly metabolic at low external [K+] (<1 mM), while it becomes increasingly nonmetabolic at higher (> 1 mM) external [K+].
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    ABSTRACT: The investigation of salt-induced changes in the proteome would highlight important genes because of a high resolution of protein separation by two-dimensional gel electrophoresis (2-DE) and protein identification by mass spectrometry and database search. Tomato (Lycopersicon esculentum Mill.) is a model plant for studying the mechanisms of plant salt tolerance. Seeds of tomato cv. Shirazy were germinated on water-agar medium. After germination, seedlings were transferred to Murashige and Skoog nutrient medium supplemented with 0, 40, 80, 120, and 160 mM NaCl. After 24 days, leaf and root samples were collected for protein extraction and shoot dry weight measurement. Alterations induced in leaf and root proteins under salt stress treatments were studied by one-dimensional SDS-PAGE. Leaf proteins were also analyzed by 2-DE. With increasing salt concentration in the medium, shoot dry weight decreased. SDS-PAGE showed induction of at least five proteins with mol wts of 30, 62, and 75 kD in roots and 38 and 46 kD in leaves. On the 2-DE gel, more than 400 protein spots were reproducibly detected. At least 18 spots showed significant changes under salt stress. Three of them corresponded to new proteins, while six proteins were up-regulated and five proteins were down-regulated by salt stress. In addition, salinity inhibited the synthesis of four leaf proteins. Ten spots were analyzed by matrix-assistant laser desorption/ionization-time of flight (MALDI-TOF), which led to the identification of some proteins, which could play a physiological role under salt stress. The expression of new proteins(enoyl-CoA hydratase, EGF receptor-like protein, salt tolerance protein, phosphoglycerate mutase-like protein, and M2D3.3 protein) under salt stress indicates that tomato leaf cells respond to salt stress by changes in different physiological processes. All identified proteins are somehow related to various salt stress responses, such as cell proliferation.
    Russian Journal of Plant Physiology 07/2007; 54(4):464-471. DOI:10.1134/S102144370704005X · 0.95 Impact Factor