Plant Stress - Global Science Books
Plant Stress - Global Science Books
Plant Stress - Global Science Books
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<strong>Plant</strong> <strong>Stress</strong><br />
Abbreviation: <strong>Plant</strong> <strong>Stress</strong><br />
Print: ISSN 1749-0359<br />
Frequency and Peer status: Biannual, Peer reviewed<br />
Scope and target readership: <strong>Plant</strong> <strong>Stress</strong> deals with the network of biotic and abiotic aspects inducing stress in plants.<br />
<strong>Plant</strong> <strong>Stress</strong> will consider manuscripts that explore the following topics:<br />
1) Environmental stress;<br />
2) Modelling stress and stress-reduction;<br />
3) Physiological, biochemical, molecular, ecological, genetic and economic aspects of plant stress at the cellular, tissue, organ or whole<br />
plant level. Preference will be given to multi-level studies;<br />
4) Programmed Cell Death directly related to a stress factor;<br />
5) Reactive oxygen species and destructive cellular mechanisms;<br />
6) <strong>Stress</strong> caused by diseases (temperate and tropical) induced by fungi, bacteria, insects, viruses, phytoplasmas and nematodes.<br />
Editor-in-Chief<br />
Jaime A. Teixeira da Silva, Kagawa University, Japan<br />
Technical Editor<br />
Kasumi Shima, Japan<br />
Statistics Advisor<br />
Marcin Kozak, Warsaw University of Life <strong>Science</strong>s, Poland<br />
Editorial Board and Advisory Panels (Listed alphabetically)<br />
Anne J. Anderson, Utah State University, USA<br />
Christian P. Andersen, US Environmental Protection Agency,<br />
USA<br />
Niranjan Baisakh, Louisiana State University, USA<br />
Saikat Kumar Basu, University of Lethbridge, Canada<br />
Pankaj Kumar Bhowmik, Lethbridge Research Centre,<br />
Agriculture and Agri-Food Canada, Canada<br />
Dimitris L. Bouranis, Agricultural University of Athens, Greece<br />
Juan Francisco Jiménez Bremont, Institute for Scientific and<br />
Technological Research of San Luis Potosi, Mexico<br />
Suriyan Cha-um, National Center for Genetic Engineering and<br />
Biotechnology, Thailand<br />
Styliani N. Chorianopoulou, Agricultural University of Athens,<br />
Greece<br />
Prem S. Chourey, USDA-ARS, USA<br />
Pio Colepicolo, Universidade de São Paulo, Brazil<br />
Tracey Cuin, University of Tasmania, Australia<br />
James F. Dat, Université de Franche-Comté – INRA, France<br />
Luis A. del Río, Estación Experimental del Zaidín, CSIC, Spain<br />
Alberto Dias, Universidade do Minho, Portugal<br />
Esmaeil Fallahi, University of Idaho, USA<br />
Jeroni Galmés, Universitat de les Iles Balears, Spain<br />
Faouzi Haouala, Institut Supérieur Agronomique de Chott<br />
Mariem, Tunisia<br />
Xinhua He, University of California, Davis, USA<br />
Luke Hendrickson, Australian National University, Australia<br />
Abdelbagi M. Ismail, International Rice Research Institute,<br />
Philippines<br />
PR Jeyaramraja, Hamelmalo College of Agriculture, The State of<br />
Eritrea<br />
Vladimir V. Kuznetsov, Russian Academy of <strong>Science</strong>s, Russia<br />
Carlos A. Labate, Escola Superior de Agricultura Luiz de Queiroz,<br />
Brazil<br />
Christophe Laloi, ETH Zurich, Switzerland<br />
Albino Maggio, University of Naples Federico II, Italy<br />
Ramamurthy Mahalingam, Oklahoma State University, USA<br />
Ezaz A. Mamun, University of Sydney, Australia<br />
Sanjib Nandy, Lethbridge Research Centre, Agriculture and<br />
Agri-Food Canada, Canada<br />
Mary M. Peet, North Carolina State University, USA<br />
S. Reza Pezeshki, University of Memphis, USA<br />
Geert Potters, University of Antwerp, Belgium<br />
Sergey Shabala, University of Tasmania, Australia<br />
Harminder Pal Singh, Panjab University, India<br />
Christine Stone, NSW Department of Primary Industries,<br />
Australia<br />
Karen Tanino, University of Saskatchewan, Canada<br />
Lining Tian, Southern Crop Protection and Food Research Centre,<br />
Agriculture and Agri-Food Canada, Canada<br />
Ilias S. Travlos, Benaki Phytopathological Institute, Greece<br />
Vincent Vadez, International Crops Research Institute for the<br />
Semi-Arid Tropics, India<br />
Boris B. Vartapetian, Timiryazev Institute of <strong>Plant</strong> Physiology,<br />
Russian Academy of <strong>Science</strong>s, Russia<br />
Selvakumar Veluchamy, North Carolina State University, USA
<strong>Global</strong> <strong>Science</strong> <strong>Books</strong>, Ltd.<br />
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Miki cho, Ikenobe 3011-2, P.O. Box 7<br />
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GSB is a trademark of <strong>Global</strong> <strong>Science</strong> <strong>Books</strong>, Ltd.<br />
<strong>Plant</strong> <strong>Stress</strong> ©2010 <strong>Global</strong> <strong>Science</strong> <strong>Books</strong>, Ltd.<br />
All rights reserved. No parts of this journal may be reproduced, stored in a retrieval system or transmitted in any form or by<br />
any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise without written permission from<br />
<strong>Global</strong> <strong>Science</strong> <strong>Books</strong>, Ltd.<br />
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address, or apply online.<br />
Guest Editor<br />
Dr. Naser A. Anjum<br />
Department of Botany, Aligarh Muslim University (AMU), Aligarh, India<br />
Agricultural Biotechnology Research Center (ABRC), Academia Sinica, Taiwan<br />
Centre for Environmental and Marine Studies (CESAM) & Department of Chemistry, University of Aveiro,<br />
Portugal<br />
Cover graphs/photos: Left scheme: Schematic representation of plant responses to Fe-overload (Sperotto et al., pp 57-69).<br />
Top, right: Lettuce anchored on polystyrofoam plank in an aeroponics system (Jie He, pp 14-30). Bottom right: Scanning<br />
electron microscopy image of Cu-sufficient pollen grain of green gram plant (Nalini Pandey, pp 1-13).<br />
Disclaimers: All comments, conclusions, opinions, and recommendations are those of the author(s), and do not necessarily<br />
reflect the views of the publisher, or the Editor(s). GSB does not specifically endorse any product mentioned in any<br />
manuscript, and accepts product descriptions and details to be an integral part of the scientific content.<br />
Printed in Japan on acid-free paper.<br />
Published: December, 2010.
The Guest Editor<br />
Dr. Naser A. Anjum<br />
ANJUM, Naser Aziz: Post-doctoral scientist at Centre for Environmental and Marine Studies (CESAM) and<br />
Department of Chemistry, University of Aveiro, Santiago Campus, Aveiro, Portugal.<br />
Dr. Anjum’s main area of research includes (a) the physiological, biochemical and molecular characterization of<br />
economically important plants suffering from abiotic stress factors, (b) involvement of mineral nutrients and other<br />
biotechnological approaches in the amelioration of abiotic stress effects in plants, (c) use of a combination of genetic,<br />
biochemical, genomic and proteomic approaches to analyze the responses of various components of ascorbate-glutathione<br />
pathway to environmental stress factors, (d) to understand stress signaling and stress tolerance, and (e) biomonitoring of salt<br />
marshes along the Atlantic coast of Europe.<br />
Born on February 4 th 1977 at Purnea, Bihar, India Dr. Anjum was awarded PhD (Botany) by Jamia Hamdard (Hamdard<br />
University), New Delhi, India in 2007. Dr. Anjum graduated and masters in Botany from Tilka Manjhi Bhagalpur University,<br />
Bhagalpur, Bihar, India. Earlier, Dr. Anjum served Aligarh Muslim University (AMU), Aligarh, India and Agricultural<br />
Biotechnology Research Center (ABRC), Academia Sinica, Taiwan in different capacities.<br />
A regular reviewer of International journals including Journal of <strong>Plant</strong> Physiology, <strong>Plant</strong> Growth Regulation, <strong>Plant</strong><br />
Biology, Australian Journal of Crop <strong>Science</strong>, Journal of <strong>Plant</strong> Breeding and Crop <strong>Science</strong> and <strong>Plant</strong> Omics Journal Dr.<br />
Anjum has been Associate Editor/Member of Editorial Boards of International journals including American-Eurasian Journal<br />
of Sustainable Agriculture, Asian and Australasian Journal of <strong>Plant</strong> <strong>Science</strong> and Biotechnology, <strong>Plant</strong> <strong>Stress</strong>, Dynamic<br />
Soil, Dynamic <strong>Plant</strong>, Functional <strong>Plant</strong> <strong>Science</strong> and Biotechnology, Eurasian Journal of Agricultural and Environmental<br />
Medicine.<br />
A life member of Indian Society for <strong>Plant</strong> Physiology Dr. Anjum is also member of other important societies including<br />
Society for Conservation of Nature and Indian Nitrogen Group.<br />
Dr. Anjum has edited a book entitled ‘Ascorbate-Glutathione Pathway and <strong>Stress</strong> Tolerance in <strong>Plant</strong>s’, published in<br />
2010 by Springer (<strong>Science</strong> + Business Media B.V.) Dordrecht, The Netherlands. His two other important In Press edited<br />
books are: 1. ‘Oxidative <strong>Stress</strong> in <strong>Plant</strong>s: Causes, Consequences and Tolerance’, and 2. ‘Nitrate in Leafy Vegetables:<br />
Toxicity and Safety Measures’ to be published by the IK International Publishing House Pvt. Ltd., New Delhi, India. Dr.<br />
Anjum’s other publications include book chapters and dozens of research articles on various aspects in International journals<br />
of repute including <strong>Plant</strong> Growth Regulation, Russian Journal of <strong>Plant</strong> Physiology, American Journal of <strong>Plant</strong> Physiology,<br />
Photosynthetica, Scientia Horticulturae, <strong>Plant</strong> <strong>Science</strong> and Journal of <strong>Plant</strong> Nutrition. Dr. Anjum has presented papers and<br />
delivered lectures in National and International Conferences and Symposia including International Botanical Congress<br />
(IBC) 2005, held in Vienna, Austria.<br />
Dr. Anjum has been selected as UGC-Dr. DS Kothari-Fellow of the year 2009 by University Grants Commissions-<br />
Ministry of Human Resource Department (UGC-MHRD), Govt. India and been Internationally Recognized as one of The<br />
World’s Foremost Achievers in his Field and been included in the 2009 Edition of Marquis Who’s Who in the World.
Foreword<br />
Naser A. Anjum<br />
Centre for Environmental and Marine Studies (CESAM) & Department of Chemistry, University of Aveiro, Santiago<br />
Campus, Aveiro, Portugal<br />
E-mail: naziz4u@yahoo.co.in, dnaanjum@gmail.com<br />
Over the last few decades, achieving sustainability in agriculture has emerged as a major goal to fulfill the requirements<br />
of enough food to feed a rapidly increasing world population in changing environmental conditions. Various biotic and<br />
abiotic stress factors continue to negatively affect various aspects of plant growth, development and productivity (Anjum et<br />
al. 2010). In fact, the relative decrease in potential maximum yields caused by biotic and abiotic stress factors varies<br />
between 54 and 82% (Bray et al. 2000; Cakmak 2005). Although concerted efforts so far have led to the development of a<br />
number of improved cultivars, yield has been virtually static owing to susceptibility of these cultivars to biotic and abiotic<br />
stresses, and a limited genetic variability in the cultivar germplasm. Nutrient management may be an important aspect for<br />
better plant growth and development and can help to achieve optimum yield of major crop plants growing in varied<br />
environmental conditions (Cakmak 2005). Besides, increasing evidence suggests that the maintenance of the mineralnutrients<br />
status of plants plays a critical role in increasing both crop productivity and resistance to environmental stress<br />
(Cakmak 2005; Umar 2006; Anjum et al. 2008a, 2008b; Umar et al. 2008; Anjum et al. 2010). The use of plant-mineral<br />
nutrients and/or plant hormones and growth regulators are, in fact, potential options which can be used to alleviate a number<br />
of abiotic stress-induced effects in plants and to achieve enhanced crop productivity as well in a sustainable way (Marschner<br />
1995; Cakmak 2005; Umar 2006; Anjum et al. 2008a, 2008b; Umar et al. 2008; Anjum et al. 2010; Syeed et al. 2010). In<br />
addition, information in the area of the role of plant nutrition in plant tolerance to various stress factors, tolerance<br />
mechanisms, variability to tolerance, breeding and biotechnology and manipulation of plant-mineral nutrients protocols for<br />
improvement crop plants against various stress factors are disorganized in the available literature.<br />
These three special issues of <strong>Plant</strong> <strong>Stress</strong> represent a tremendous attempt, through invited reviews, mini reviews and<br />
articles from leading scientists and researchers working worldwide on the link between plant nutrition and abiotic stresses.<br />
The main objective of these volumes is to provide state-of-the-art and up-to-date knowledge of recent developments in the<br />
understanding of plant responses to major abiotic stresses and the role of plant nutrition in the amelioration of abiotic stress<br />
factor-induced effects in crop plants in a single literature source. These special issues critically evaluate the available<br />
literature and discuss major problems through an understanding of the physiology, biochemistry and molecular biology of<br />
plant stress responses and mechanisms of mineral nutrition-induced stress tolerance in plants in detail. However, to increase<br />
our understanding of the interaction between plant nutrition and abiotic stress tolerance, much more work is needed to<br />
uncover the complexities of individual major functions in plants.<br />
I honestly hope that these special issues of <strong>Plant</strong> <strong>Stress</strong> shall be a great help to students, researchers and professionals in<br />
botany, plant environmental science studies, agriculture, plant physiology and molecular biology, in both academic and<br />
industrial sectors.<br />
I am thankful to contributors for their significant manuscripts and in particular to the reviewers who assisted a lot in the<br />
reviewing process and all the referees who provided their valuable comments thus making this special issue-cum-book<br />
possible.<br />
I would like to offer my grateful thanks to the Foundation for <strong>Science</strong> & Technology (FCT), Portugal<br />
(SFRH/BPD/64690/2009), Council of Scientific & Industrial Research (CSIR), New Delhi, India [(9/112(0401)2K8-EMR-I<br />
(312208/2K7/1)] and to the Agricultural Biotechnology Research Center (ABRC), Academia Sinica, Taiwan for financial
supports to my research.<br />
Last but not least, I must be grateful to Dr. Jaime, the Editor-in-Chief of <strong>Plant</strong> <strong>Stress</strong> and <strong>Global</strong> <strong>Science</strong> <strong>Books</strong> Pvt. Ltd,<br />
United Kingdom, who made these efforts successful in bringing out the present treatise on <strong>Plant</strong> Nutrition and Abiotic <strong>Stress</strong><br />
Tolerance.<br />
Naser A. Anjum, PhD<br />
Guest Editor<br />
Post-Doctoral Scientist at Centre for Environmental and Marine Studies (CESAM) & Department of Chemistry, University<br />
of Aveiro, Santiago Campus, Aveiro, Portugal.<br />
Formerly at:<br />
Department of Botany, Aligarh Muslim University, Aligarh 202 002, India; and<br />
Academia Sinica Biotechnology Center in Southern Taiwan, Tainan County, 74146 Taiwan<br />
REFERENCES<br />
Anjum NA, Umar S, Singh S, Nazar R, Khan NA (2008a) Sulfur assimilation and cadmium tolerance in plants. In: Khan<br />
NA, Singh S, Umar S (Eds) Sulfur Assimilation and Abiotic <strong>Stress</strong> in <strong>Plant</strong>s, Springer-Verlag, pp 271-302<br />
Anjum NA, Umar S, Ahmad A, Iqbal M, Khan NA (2008b) Sulphur protects mustard (Brassica campestris L.) from<br />
cadmium toxicity by improving leaf ascorbate and glutathione. <strong>Plant</strong> Growth Regulation 54, 271-279<br />
Anjum NA, Umar S, Chan M-T (2010) (Eds) Ascorbate-Glutathione Pathway and <strong>Stress</strong> Tolerance in <strong>Plant</strong>s, Springer<br />
(<strong>Science</strong> + Business Media B.V.) Dordrecht, The Netherlands<br />
Bray EA, Bailey-Serres J, Weretilnyk E (2000) Responses to abiotic stresses. In: Buchanan B, Gruissem W, Jones R (Eds)<br />
Biochemistry and Molecular Biology of <strong>Plant</strong>s, American Society of <strong>Plant</strong> Physiologists, pp 1158-1203<br />
Cakmak I (2005) The role of potassium in alleviating detrimental effects of abiotic stresses in plants. Journal of <strong>Plant</strong><br />
Nutrition and Soil <strong>Science</strong> 168, 521-530<br />
Marschner H (1995) Mineral Nutrition of Higher <strong>Plant</strong>s, Academic Press, New York<br />
Syeed S, Anjum NA, Nazar R, Iqbal N, Masood A, Khan NA (2010) Salicylic acid-mediated changes in photosynthesis,<br />
nutrients content and antioxidant metabolism in two mustard (Brassica juncea L.) cultivars differing in salt tolerance.<br />
Acta Physiologiae <strong>Plant</strong>arum, in press<br />
Umar S (2006) Alleviating adverse effects of water stress on yield of sorghum, mustard and groughd by potassium<br />
application. Pakistan Journal of Botany 38, 1373-1380<br />
Umar S, Diva I, Anjum NA, Iqbal M (2008) Potassium nutrition reduces cadmium accumulation and oxidative burst in<br />
mustard (Brassica campestris L.). Electronic International Fertilizer Correspondent 16 (June), 6-10<br />
December, 2010
SPECIAL ISSUE: CONTENTS<br />
Nalini Pandey (India) Role of Micronutrients in Reproductive Physiology of <strong>Plant</strong>s<br />
Jie He (Singapore) Mineral Nutrition of Aeroponically Grown Subtropical and Temperate Crops in the Tropics with<br />
Manipulation of Root-Zone Temperature at Different Growth Irradiances<br />
Amrit L. Singh, Ram S. Jat, Vidya Chaudhari, Himanshu Bariya, Seema J. Sharma (India) Toxicities and Tolerance of<br />
Mineral Elements Boron, Cobalt, Molybdenum and Nickel in Crop <strong>Plant</strong>s<br />
Raul Antonio Sperotto, Felipe Klein Ricachenevsky, Ricardo José Stein, Vinicius de Abreu Waldow, Janette Palma Fett<br />
(Brazil) Iron <strong>Stress</strong> in <strong>Plant</strong>s: Dealing with Deprivation and Overload<br />
Kanwar L. Sahrawat (India) Reducing Iron Toxicity in Lowland Rice with Tolerant Genotypes and <strong>Plant</strong> Nutrition<br />
Bhupinder Singh, Seva Nayak Dheeravathu, Kalidindi Usha (India) Micronutrient Deficiency: A <strong>Global</strong> Challenge and<br />
Physiological Approach to Improve Grain Productivity under Low Zinc Availability<br />
Girdhar K. Pandey, Akhilesh K. Yadav, Poonam Kanwar, Narendra Tuteja (India) Role of Calcium in Regulating<br />
Potassium-Sodium Homeostasis and Potassium as Nutrient Signal during Abiotic <strong>Stress</strong> Conditions<br />
Ashraf M, Muhammad Afzal, Rashid Ahmad, Muhammad Aamer Maqsood, Sher Muhammad Shahzad, Ahsan Aziz,<br />
Naeem Akhtar (Pakistan) Silicon Management for Mitigating Abiotic <strong>Stress</strong> Effects in <strong>Plant</strong>s<br />
María Begoña Herrera-Rodríguez, Agustín González-Fontes, Jesús Rexach, Juan J. Camacho-Cristóbal, José M.<br />
Maldonado, María Teresa Navarro-Gochicoa (Spain) Role of Boron in Vascular <strong>Plant</strong>s and Response Mechanisms to Boron<br />
<strong>Stress</strong>es<br />
1<br />
14<br />
31<br />
57<br />
70<br />
76<br />
94<br />
104<br />
115
Nalini Pandey (India) Role of Micronutrients in Reproductive Physiology of <strong>Plant</strong>s (pp 1-13)<br />
ABSTRACT<br />
Invited Review: <strong>Plant</strong> reproductive biology is a key developmental process and has a great impact on plant productivity.<br />
Reproduction in plant involves the interaction between the male and female gametophyte which depend on the sporophyte for<br />
their nutrient requirement. Till recently, it was thought that adequate supply of micronutrients (Fe, Mn, Cu, Zn, Mo and B) was<br />
required during the period of active vegetative growth. It has lately been shown that good vegetative growth of plants does not<br />
necessarily go hand in hand with a high seed yield. In a large number of crops even under conditions of moderate micronutrient<br />
deficiencies when biomass production is marginally reduced, the reproductive yield is severely decreased. This suggests a<br />
requirement of micronutrients for floral induction and reproductive development independent of the requirement for production<br />
of necessary assimilates. Sufficient evidence has emerged to show that the micronutrients, in particular Cu, Zn and B, are<br />
critically required for reproductive development and that their requirement is possibly higher than what can be met by<br />
retranslocation from the vegetative parts of the mother plants. Application of these micronutrients during an early stage of<br />
reproductive phase make substantial improvement in pollen fertility, pollen-stigma interaction, seed setting and seed quality.<br />
While there are numerous reports of response to micronutrient fertilization benefiting harvest yield of plants, information on<br />
involvement of the micronutrients in plant reproductive development is limited. In recent years the identification of a number of<br />
genes for the floral organs and specific transcription factors like the zinc-fingers has given new impetus to the role of<br />
micronutrients in transcriptional regulation of reproductive development. In this review the current status on the systematic<br />
studies on the role of micronutrients in reproductive biology of plants is discussed.<br />
Jie He (Singapore) Mineral Nutrition of Aeroponically Grown Subtropical and Temperate Crops in the Tropics with Manipulation<br />
of Root-Zone Temperature at Different Growth Irradiances (pp 14-30)<br />
ABSTRACT<br />
Invited Review: <strong>Plant</strong> growth and productivity are often limited by high root-zone temperatures (RZT) which restricts the growth<br />
of subtropical and temperate crops in the tropics. High RZT temperature coupled with low growth irradiances during cloudy days<br />
which mainly lead to poor root development and thus causes negative impact on the mineral uptake and assimilation. However,<br />
certain subtropical and temperate crops have successfully been grown aeroponically in the tropics by simply cooling their roots<br />
while their aerial portions are subjected to hot fluctuating ambient temperatures. This review first discusses the effects of RZT<br />
and growth irradiance on root morphology and its biomass, the effect of RZT on uptake and transport of several macro nutrients<br />
such as N [nitrogen, mainly nitrate, (NO − 3 )], P (H 2PO − 4 , phosphate), K (potassium) and Ca (calcium), and micro nutrient Fe<br />
(iron) under different growth irradiances. The impact of RZT and growth irradiance on the assimilation of NO - 3 (the form of N<br />
nutrient given to the aeroponically grown plants) and the site of NO - 3 assimilation are also addressed.<br />
Amrit L. Singh, Ram S. Jat, Vidya Chaudhari, Himanshu Bariya, Seema J. Sharma (India) Toxicities and Tolerance of<br />
Mineral Elements Boron, Cobalt, Molybdenum and Nickel in Crop <strong>Plant</strong>s (pp 31-56)<br />
ABSTRACT<br />
Invited Review: The minerals boron (B), cobalt (Co), molybdenum (Mo) and Nickel (Ni) are beneficial to plant in trace amounts,<br />
but excess levels of these cause toxicity limiting crop production. An attempt was made to review the phytotoxicity symptoms,<br />
effects on growth and physiology and tolerance and amelioration of these toxicities in crop plants. Though, chlorosis and<br />
necrosis of leaves are the common expression of toxicities of these minerals and except B the critical toxic concentration of Co,<br />
Mo and Ni in soil has been worked out only for a few crops, the toxicity responses of these minerals in soil and plant tissues<br />
vary considerably across the soils and crop genotypes. These toxicities reduce chlorophyll, affect cell metabolites and enzymes<br />
specially antioxidant and lipid peroxidation, alter nutrient transport and have negative effects on cellular functioning, these all<br />
result in reduced growth and yield. Existence of genetic variation among the crop genotypes highlight the differences in<br />
tolerance and scoring for toxicity symptoms and biomass at early growth stages can be considered as reliable criteria for<br />
screening for tolerance to toxicity. The Bo1 gene provides a major source of B toxicity tolerance. The restriction of uptake and<br />
transport and internal tolerance mechanisms are the two important criteria which plants employ to combat high external<br />
concentrations and hence tolerance could be attributed to the lower B, Co, Mo and Ni content of seed and lower uptake or<br />
accumulation of these in the root and shoot and high yield in toxic soils. Ameliorating high-mineral soils using soil amendments<br />
is expensive and extremely difficult. Use of tolerant crop genotypes, phytoremediation by tolerant crops, and inoculations of<br />
beneficial microorganisms are the solutions.
Raul Antonio Sperotto, Felipe Klein Ricachenevsky, Ricardo José Stein, Vinicius de Abreu Waldow, Janette Palma Fett<br />
(Brazil) Iron <strong>Stress</strong> in <strong>Plant</strong>s: Dealing with Deprivation and Overload (pp 57-69)<br />
ABSTRACT<br />
Invited Review: Iron (Fe) is an essential nutrient for plants and one of the most abundant elements in soils. However, it is<br />
nearly inaccessible to plants because of its poor solubility in aerobic conditions at neutral or basic pH, resulting in much lower<br />
concentrations than required for the optimal growth of plants. However, when Fe is taken up in excess of cellular needs, it<br />
becomes highly toxic, since both Fe 2+ and Fe 3+ can act as catalysts in the formation of hydroxyl radicals, which are potent<br />
oxidizing agents that may damage DNA, proteins and lipids. <strong>Plant</strong>s must be able to sense and respond to Fe stress in terms of<br />
both Fe-deprivation and Fe-overload. Depending on the level of severity, plants are unable to deal with such stress and undergo<br />
dramatic changes in cellular metabolism with a sequential dismantling of cellular structures, resulting in growth inhibition and<br />
ultimately plant death. Therefore, plants must tightly regulate Fe levels within the cell to ensure that Fe is present at adequate<br />
levels. Here, we describe recent progress made in understanding how Fe is sensed by plants, and how plants are affected by<br />
and try to deal with non-optimal Fe concentrations.<br />
Kanwar L. Sahrawat (India) Reducing Iron Toxicity in Lowland Rice with Tolerant Genotypes and <strong>Plant</strong> Nutrition (pp 70-75)<br />
ABSTRACT<br />
Invited Mini-Review: Iron toxicity is a widespread nutrient disorder of lowland rice grown in tropical and sub-tropical regions of<br />
the world on acid sulfate soils, Ultisols and sandy soils with a low cation exchange capacity, moderate to high in acidity, high in<br />
easily reducible or active iron and low to moderately high in organic matter. The stress is caused by a high concentration of<br />
ferrous iron in soil solution. It is estimated that iron toxicity reduces lowland rice yields by 12-100%, depending on the iron<br />
tolerance of the genotype, intensity of the iron toxicity stress and soil fertility status. Iron toxicity can be reduced by using<br />
iron-tolerant rice genotypes and through soil, water and nutrient management practices. The objective of this paper is to<br />
critically assess the pertinent literature on the role of iron-tolerant rice genotypes and other plant nutrients in reducing iron<br />
toxicity in lowland rice. It is emphasized that research should provide knowledge that would be used for increasing lowland rice<br />
production and productivity on iron-toxic wetlands on a sustainable basis by integration of genetic tolerance to iron toxicity with<br />
soil, water and nutrient management.<br />
Bhupinder Singh, Seva Nayak Dheeravathu, Kalidindi Usha (India) Micronutrient Deficiency: A <strong>Global</strong> Challenge and<br />
Physiological Approach to Improve Grain Productivity under Low Zinc Availability (pp 76-93)<br />
ABSTRACT<br />
Invited Review: Micronutrient deficiency in soils is a fast emerging phenomenon and a challenging abiotic stress in world<br />
agriculture. Most important micronutrients that the developing and developed world is concerned from point of view of<br />
sustaining grain productivity and malnutrition in human beings are iron and zinc. Biofortification of staple food crops with<br />
micronutrients by either breeding for higher uptake efficiency or fertilization can be an effective strategy to address widespread<br />
dietary deficiency in human populations. Cereal species greatly differ in their micronutrient efficiency (MiE), defined in this paper<br />
as the ability of a plant to grow and yield well under micronutrient deficiency. MiE generally has been attributed to the efficiency<br />
of acquisition of nutrients under conditions of their low soil availability rather than to its utilisation or (re)-translocation within a<br />
plant. A higher zinc and iron acquisition efficiency of genotypes could be attributed to either or all of the following; an efficient<br />
ionic metal uptake system, better root architecture i.e., long and fine roots with architecture favouring exploitation of<br />
micronutrients from larger soil volume, higher synthesis and release of metal mobilising phytosiderophore by the roots and<br />
uptake of Fe- and Zn-phytosiderophore complex. Seed Zn content has also been suggested to affect the respective MiE. Root<br />
morphology and characteristics and interaction between micronutrients and other ionic radicals have been implicated as<br />
determinants of MiE. This review attempts to examine critically the scanty and scattered reports available on status of<br />
micronutrient deficiency with special reference to Zn, globally; morphological, biochemical and physiological basis of regulation<br />
of MiE in cereals and approaches to improve MiE in terms of grain productivity and grain Fe and Zn vis-à-vis its bioavailability<br />
under conditions of poor micronutrient availability.<br />
Girdhar K. Pandey, Akhilesh K. Yadav, Poonam Kanwar, Narendra Tuteja (India) Role of Calcium in Regulating<br />
Potassium-Sodium Homeostasis and Potassium as Nutrient Signal during Abiotic <strong>Stress</strong> Conditions (pp 94-103)
ABSTRACT<br />
Invited Review: Calcium is a ubiquitous cation, which serves as a second messenger for numerous signals and confers<br />
specific cellular responses in eukaryotes. Recent studies have established a concept termed ‘Ca 2+ signature’ that specifies Ca 2+<br />
changes triggered by each signal. However, it is very fascinating how this pervasive cation can translate an infinite number of<br />
stimuli into unique stimulus-dependent responses. Ca 2+ is a fundamental component of nutrition signaling under stress<br />
condition. It interacts with various calcium sensors, which are directly involved in various molecular, biochemical and cellular<br />
changes occurring during the plant’s adaptation to nutritional stress. Recently, in calcium signaling in plants, the CBL-CIPK<br />
protein network has been implicated in phytohormone (ABA), abiotic stress and potassium nutrition signaling. This review will<br />
mainly focus on the functional relationship of calcium-mediated salt stress tolerance, potassium nutrition, and<br />
potassium-sodium homeostasis by involvement of the CBL-CIPK complex.<br />
Ashraf M, Muhammad Afzal, Rashid Ahmad, Muhammad Aamer Maqsood, Sher Muhammad Shahzad, Ahsan Aziz,<br />
Naeem Akhtar (Pakistan) Silicon Management for Mitigating Abiotic <strong>Stress</strong> Effects in <strong>Plant</strong>s (pp 104-114)<br />
ABSTRACT<br />
Invited Review: Abiotic stress factors including salinity, drought, heat, frost, lodging, shading and ion toxicities may adversely<br />
affect the crop productivity and quality. Increasing evidences suggest that adequate regulation of silicon (Si) may enable the<br />
plants to survive the stress environment in a wide variety of crops. Si, once absorbed by the xylem veins, is deposited in the cell<br />
wall of roots, reducing the apoplastic bypass flow, provides binding sites for salts and, thereby, reduces the uptake and<br />
translocation of salts from roots to shoots. Si deposition in the cell wall increases the rigidity of cell wall and reduces the loss of<br />
water through transpiration with a resultant decrease in salt uptake. An increase in internal storage of water within plant tissue,<br />
due to reduced transpiration, allows higher growth rate and consequently mitigating detrimental effects of abiotic stresses. Si<br />
stimulates antioxidant defense system which helps the plants to maintain the desired level of reactive oxygen species in stress<br />
environment. <strong>Plant</strong>s grown in the presence of Si show an erect growth, minimizing the amount of shade and allowing better<br />
distribution of light within the canopy. Si can lower electrolyte leakage, promoting photosynthetic activity in plants grown in<br />
stress environment. Si can positively affect the activities of certain enzymes and decrease the injury caused by abiotic stress<br />
factors. Si reduces the toxicity of elements such as iron, aluminum, manganese and cadmium through reduced uptake,<br />
complexation or immobilization and compartmentation or homogenous distribution of metal ions within the plant. This review<br />
deals with the current knowledge of beneficial effects of Si with focuses being on possible mechanisms of minimizing abiotic<br />
stress effects on plant growth and development.<br />
María Begoña Herrera-Rodríguez, Agustín González-Fontes, Jesús Rexach, Juan J. Camacho-Cristóbal, José M.<br />
Maldonado, María Teresa Navarro-Gochicoa (Spain) Role of Boron in Vascular <strong>Plant</strong>s and Response Mechanisms to Boron<br />
<strong>Stress</strong>es (pp 115-122)<br />
ABSTRACT<br />
Invited Review: To date, the primordial function of boron is its structural role in the cell wall through stabilization of molecules<br />
containing cis-diol groups (borate esters with apiose residues of rhamnogalacturonan II). Nonetheless, boron is a micronutrient<br />
also involved in a great variety of physiological processes in vascular plants. However the mechanisms underlying the various<br />
metabolic disorders caused by boron deficiency are indeed unknown. Recently it has been reported that boron deficiency and<br />
toxicity induce stress-responsive genes. In this contribution we review the mechanisms involved in boron uptake and<br />
distribution, the role of boron in vascular plants, the effects of boron deficiency and toxicity on them, as well as the interaction<br />
boron toxicity and salt stress. In addition, we discuss the most recent hypotheses proposed to explain how boron could exert its<br />
function in vascular plants from a mechanistic point of view. The importance of understanding the role of boron in plants as well<br />
as the response mechanisms to its deficiency and toxicity will allow us to improve the tolerance of crops to boron stresses.