Mohd Rafiq Wani

Alleviation of cadmium toxicity in Brassica juncea L. (Czern. & Coss.) by calcium application involves various physiological and biochemical strategies.

Calcium (Ca) plays important role in plant development and response to various environmental stresses. However, its involvement in mitigation of heavy metal stress in plants remains elusive. In this study, we examined the effect of Ca (50 mM) in controlling cadmium (Cd) uptake in mustard (Brassica juncea L.) plants exposed to toxic levels of Cd (200 mg L−1 and 300 mg L−1). The Cd treatment showed substantial decrease in plant height, root length, dry weight, pigments and protein content. Application of Ca improved the growth and biomass yield of the Cd-stressed mustard seedlings. More importantly, the oil content of mustard seeds of Cd-stressed plants was also enhanced with Ca treatment. Proline was significantly increased in mustard plants under Cd stress, and exogenously sprayed Ca was found to have a positive impact on proline content in Cd-stressed plants. Different concentrations of Cd increased lipid peroxidation but the application of Ca minimized it to appreciable level in Cd-treated plants. Excessive Cd treatment enhanced the activities of antioxidant enzymes superoxide dismutase, ascorbate peroxidase and glutathione reductase, which were further enhanced by the addition of Ca. Additionally, Cd stress caused reduced uptake of essential elements and increased Cd accumulation in roots and shoots. However, application of Ca enhanced the concentration of essential elements and decreased Cd accumulation in Cd-stressed plants. Our results indicated that application of Ca enables mustard plant to withstand the deleterious effect of Cd, resulting in improved growth and seed quality of mustard plants.

Drought Tolerance: Role of Organic Osmolytes, Growth Regulators, and Mineral Nutrients

Plants are continuously exposed to various environmental stresses, which cause alteration in every physiological and biochemical pathway. Plants have evolved several mechanisms that allow a plant species to tolerate/combat stress. Greater synthesis and accumulation of compatible organic osmolytes and proper mineral nutrition help plants to bring osmoregulation so that the cell water content and turgor is maintained. Under stress conditions, synthesis and accumulation of several osmolytes like free sugars, amino compounds, such as proline and glycine betaine, sugar alcohols like mannitol, and other low molecular weight metabolites are increased. Macro mineral elements such as nitrogen, phosphorus, potassium, and calcium are required for normal growth and development of plants and are known to stimulate the synthesis of osmotically active solutes. Moreover, they are actively implicated in several physiological processes including enzyme activation, transport, photosynthesis, and protein synthesis. Various phytohormones are known to have defensive roles in plants exposed to environmental stresses and their synthesis and accumulation are upregulated on exposure to environmental stress. Present review throws light on the role of organic osmolytes, mineral nutrients, and also growth regulators especially abscisic acid, ethylene, and salicylic acid in increasing the plant tolerance to drought stress.

Biochemical and Molecular Approaches for Drought Tolerance in Plants

Drought is a worldwide problem, constraining global crop production and quality sternly and recent global climate change has made this situation graver. It is a complex physio-chemical process in which many biological micro and macromolecules, such as nucleic acids (DNA, RNA, Micro-RNA), proteins, carbohydrates, lipids, hormones, ions, free radicals, and mineral elements are involved. In addition, drought is also related to other biotic and abiotic stresses, e.g. salt stress, cold stress, high temperature stress, UV-B damage, wounding, etc. and it is reported that this phenomenon is connected with almost all aspects of biology. Plants have evolved mechanisms that allow them to adapt and survive under water deficit conditions. Compatible solutes which are induced due to drought stress do not interfere with the normal functioning of the cell. They protect the cell organelles from harsh effects of drought. Here, we have reviewed the effect of drought stress on biochemical attributes in plants. This article also describes the role of genetic engineering in alleviating drought stress in plants.

Improvement of crops in the era of climatic changes

Chapter 1 Citrus Rootstocks for Improving the Horticultural Performance and Physiological Responses under Constraining Environments Rafael V. Ribeiro, Erick Espinoza-Nunez, Jorgino Pompeu Junior, Francisco A. A. Mourao Filho and Eduardo C. Machado Chapter 2 Role of Silicon in Enrichment of Plant Nutrients and Protection from Biotic and Abiotic Stresses Durgesh Kumar Tripathi, Vijay Pratap Singh, Savita Gangwar, Sheo Mohan Prasad, Jagat Narayan Maurya and Devendra Kumar Chauhan Chapter 3 Transgenic Approaches for Phytoextraction of Heavy Metals Atul Bhargava and Shilpi Srivastava Chapter 4 Using an Allometric Model for the Accumulation of Mineral Nutrients in Crops Under Saline-Water Stress: A Field Experience in Fertigation Enrique Misle, Besma Kahlaoui, Estrella Garrido and Mohamed Hachicha Chapter 5 Control of Biotic and Abiotic Stresses in Cultivated Plants by the Use of Biostimulant Microorganisms Adriano Sofo, Maria Nuzzaci, Antonella Vitti, Giuseppe Tataranni and Antonio Scopa Chapter 6 Cyclic Nucleotides and Nucleotide Cyclases in Plants under Stress Malgorzata Pietrowska-Borek, Tamara Chadzinikolau and Slawomir Borek Chapter 7 Breeding and Transgenic Approaches for Development of Abiotic Stress Tolerance in Rice Satendra K. Mangrauthia, P. Revathi, Surekha Agarwal, Arun Kumar Singh and V. P. Bhadana Chapter 8 Mineral Bioavailability Through Mutation Breeding In Pulse Crops: A Review Mohammad Imran Kozgar, Mohd Rafiq Wani, Samiullah Khan and Parvaiz Ahmad Chapter 9 Abiotic Stress and Control of Yield in Cereals Bhinu V-S Pillai and Sreekala Chellamma Chapter 10 Improvement of Crop Production under Saline Stress by a Bio-Hydraulic Approach Besma Kahlaoui, Mohamed Hachicha, Enrique Misle, Belgacem Hanchi and Jorge Teixeira Chapter 11 Induced Mutagenesis for the Improvement of Pulse Crops with Special Reference to Mungbean-A Review Update Mohd Rafiq Wani, M. Imran Kozgar, Samiullah Khan, M. Abbas Ahangar and Parvaiz Ahmad Chapter 12 Crop Improvement through Tissue Culture L. F. De Filippis Chapter 13 Agricultural Pollution: An Emerging Issue Aqsa Abbasi, Ayesha Sajid, Namra Haq, Sammia Rahman, Zujaja-Tul-Misbah, Gul Sanober, Muhammad Ashraf and Alvina Gul Kazi

Brassicas: Responses and Tolerance to Heavy Metal Stress

Brassica is considered as an important crop all over the world owing to its economically important products. B.juncea and B.napus are cultivated as oilseed crops globally. Heavy metal (HM) stress is one of the abiotic stresses that limit plant growth and development. Root and shoot lengths and fresh and dry weights have been observed to act as accumulators as well as indicators of metal toxicity in crops. Brassica has a potential to combat the metal-induced stress, thereby reducing the damage by undergoing various types of adaptations. However, cost-effective techniques are available in order to minimize the toxicity and to protect the surroundings from HM stress. Decrease in chlorophyll content confers to weak uptake of mineral ions due to the interference of HMs in plants. Nevertheless, low concentrations of some HMs demonstrate an efficient yield in some species. HMs disturb the composition of fatty acids and as a result lead to tremendous changes in lipid membrane that may ultimately cause lipid peroxidation. Proline accumulation enhances the tolerance level under osmotic stress and is known to regulate the water balance in crop plants. Increased glutathione (GSH) in B. napus and B. juncea, on exposure to HMs, has shown its active involvement in detoxification of free radicals either directly or through certain enzymes. Phytochelations are one of the important methods to reduce the phytotoxicity by binding complexes with high-affinity ligands in the vacuole, thereby keeping the released toxins away from the metal-sensitive metabolic centers in the cytoplasm. Ascorbate–GSH cycle plays an efficient role in reactive oxygen species (ROS) detoxification released through abiotic stress. Besides, ROS shows release of new isozymes of peroxidases. Genetic engineering has been established to enhance the plant’s ability to endure and mitigate the environmental stress. This involves the insertion of foreign DNA into nuclear genome and genomic chloroplast. However, gene expression can be regulated by various promoters. Several transgenic approaches have been carried out successfully with enhanced accumulation of HMs in B. juncea cultivars. There is lot of scope to understand the mechanism of HM uptake as well as the capacity of plants to withstand the environmental stresses.

Induced Mutagenesis for the Improvement of Pulse Crops with Special Reference to Mung Bean: A Review Update

In the era of burgeoning human population, the ghosts of hunger are making its impact among millions of people all around. The conditions are worse at present due to growing undernourishment (FAO, The state of food insecurity in the world economic crises—impacts and lessons learned. Tenth progress report on world hunger, FAO, United Nations, Rome, 2009). The rescue lies in tailoring the better varieties of crop plants, rich in nutrition and high in yield. Pulses are cherished for their lavishness in proteins which make them indispensable in daily human diet. The breeding of pulses by traditional methods has been practiced for centuries; however, these conventional methods are now insufficient to make any further breakthrough to cope with the world’s mounting food demand. The major constraint in the development of improved varieties is the limited genetic variability among the existing genotypes. Induced mutagenesis is one of those novel techniques, which impart variation in subject crops through sustainable approach. A vast amount of genetic variability of both quantitative and qualitative traits has been generated through experimental mutagenesis in the past 30 years. Characterization of mutated traits has greatly advanced our understanding of the underlying mechanisms of important traits. Considering the fact that mutations are generally deleterious, the number of mutant cultivars released globally in major food crops especially pulses with novel traits is still impressive. Although the crop improvement work on mung bean (Vigna radiata (L.) Wilczek) and other legumes has been in progress for the past several years at different state agriculture universities and ICAR institutes in India, the programs lack organized and coordinated efforts in achieving the desired goals.

Mutation Breeding: A Novel Technique for Genetic Improvement of Pulse Crops Particularly Chickpea (Cicer arietinum L.)

Breeding of pulses, especially chickpea, by exploiting genetic diversity using conventional methods has been practiced in the past. Nevertheless, these methods at present are inadequate for making any significant breakthrough to handle the world’s ever-increasing food demand. In this bizarre scenario, induced mutations have emerged as big relief, and are largely exploited for developing improved high-yielding crop varieties and for discovering desired genes that control important agronomical traits. Gene mutation, leading to the quality advancement of well-adapted existing varieties, has been the pedestal for germplasm improvement. Pulses are more prone to biotic and abiotic stresses as compared to cereals. As a result, there is a serious need to develop such varieties having high resistance to the above-mentioned stresses. During the past eight and a half decades, around 3,139 improved crop varieties have been released globally derived either as direct mutants or from their progenies (http://mvgs.iaea.org). Vast numbers of these varieties like cereals, pulses , oil crops, root and tuber crops and ornamentals have been released in developing countries for cultivation, including India, resulting in massive economic impact. Lately, mutagenesis has received an immense impel for its use in a newfangled promising technique known as targeting induced local lesions in genomes. With the unfolding of novel biological fields such as genomics, functional genomics, bioinformatics and the emergence of other technologies based on these sciences, there has been an increased surge in induced mutations within the scientific community. The knowledge of functional and basic genetics of model legume crops will benefit chickpea breeders to comprehend that marker-assisted selection has great potential to develop biotic and abiotic stress -resistant varieties. The basic understanding of genes, which direct major agronomical traits, is essential for plant breeders to frame apposite approaches and execute them in breeding programmes for promising results. In this era, with growing human population, hunger ghosts are haunting millions of people all around. Under these circumstances, the salvaging step lies in tailoring better crop varieties embedded with superior proteins, minerals and high yield. Mutagenic agents, physical as well as chemical, are used to induce mutations and generate variations from which desired mutants may be selected. However, basic information vis-a-vis effectiveness of various mutagens and their possible role in generating polygenic variability is meagre among pulses in general and chickpea in particular. Hence, the present review condenses various facets of contemporary knowledge for pulse crop varietal improvement, particularly chickpea, through induced mutagenesis with special thrust on qualitative as well as yield-attributing traits.

Wheat Improvement: Historical Perspective and Mutational Approach—A Review

Wheat (Triticum aestivum L.) occupies a prominent position among the cereal crops and supplements dietary requirement of nearly one-third of the world’s population. The importance of wheat can be gauged by the fact that the Food and Agricultural Organization (FAO) of the United Nations has chosen a wheat spike in its symbol with the description “Let there be bread.” In the present scenario, the likings for wheat-based food products have increased, thus widening the scope for industrial production and consequently providing the livelihood to millions of people world over directly or indirectly. In India, the All India Coordinated Wheat Improvement Project established in 1965 by Indian Council of Agricultural Research (ICAR) and later raised to the status of Directorate of Wheat Research is largely involved with the coordination of wheat research in the country. More than 300 varieties of wheat suitable for different agronomical conditions of the country have been released by the organization. Though, at present, India is self-sufficient in wheat production, but the emerging challenges of population explosion, environmental stresses, new pathogenic races, decreased arable lands, depleting water resources, and degraded soils make it imperative to consistently aim at the development of efficient and promising varieties so that the food security in the country can be ensured. It is estimated that, by 2030, India will require some 100 million tonnes of wheat to satisfactorily feed its population. Therefore, there is a pressing need to enhance wheat productivity so as to keep up the pace with the mounting demand and to maintain price stability by making it physically available and economically accessible. The key objectives of wheat breeding are yield enhancement, good nutritional quality, biotic and/or abiotic stress tolerance, etc. Presently, conventional methods of wheat breeding are not enough to make any considerable breakthrough to cope with the world’s rising demand, with the exhausted genetic variability among the existing genotypes being the major constraint in the progression of these varieties and also making them susceptible to various abiotic and biotic stresses. In this scenario, the possibility offered by experimental mutagenesis to induce new genetic variability is of extreme interest, as it has played an enormous role in increasing the world food security by contributing significantly in the improvement of wheat crop production. The present chapter enfolds various historical aspects in addition to contemporary knowledge of wheat crop improvement programs through induced mutagenesis.

The Role of Cytological Aberrations in Crop Improvement Through Induced Mutagenesis

Mutation breeding for the past few decades has been pivotal in developing such high-yielding varieties which greatly help to feed the ever-growing global human population. Although induced mutations have great relevance for growing superior plant types in different crops plant, most of them are lethal or semi-lethal and do not have any practical values possibly due to the doses monitored and/or mutagens employed. Thus, to administer successful mutagenesis, selection of efficient mutagen and treatment is a basic prerequisite. The cytological analysis with respect to meiotic or mitotic behavior is considered one of the most reliable indices to estimate the potency of a mutagen. Hence, investigations on cytological aberrations and their genetic consequences form an integral part for most of the mutation studies and provide a considerable clue to assess the sensitivity of plants for different mutagens. In addition, the cytogenetic information vis-a-vis chromosome deformities provides an exhaustive overview related to the improvement of the desired trait via induced mutagenesis. The present documentation is an attempt to reveal the impact of mutagens on cytological behavior and their overall role in crop improvement.

Mineral Bioavailability Through Mutation Breeding in Pulse Crops: A Review

For any national food security program, crop production plays an important role to fulfill the demands of dwelling inhabitants. Induced mutagenesis is one of the important and practical fields of breeding strategies, through which the biggest accomplishments have been gained with the development of mutant varieties, especially for cereal crops, which are superior for certain useful traits like yield and minerals components. In spite of these achievements, the people of Indian subcontinent and other developing nations are facing immense scarcity of food and are in most awful condition with concomitant increase in malnutrition. In order to reduce food insecurity and malnutrition alarm, nations like India have to revitalize the policies and strategies of agriculture practices. Additionally, the research activities related to mutation breeding on other crops, especially pulses, have to be enhanced which can act as an aiding weapon to boost up the crop production. In the present review, an effort has been put forward to assess the impact of mutation breeding on crop production and mineral bioavailability enhancement in different crop plants. As mutation breeding has become the most successful field of application of nuclear techniques in food and agriculture all over the world, finishing annotations are being put in front to let the policy makers know the paybacks of enhancing mutation breeding research in crops especially pulses, of which India being the largest producer.