http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2013 , Hindawi Publishing Corporation . All rights reserved. Thu, 11 Apr 2013 11:44:56 +0000 http://www.hindawi.com/journals/jb/2013/690549/ Similarities in structural organization of the culm in Poaceae, Juncaceae, and Cyperaceae such as leaf sheaths and the presence of intercalary meristems at every node suggest the same mechanical properties and, accordingly, the same functionality. Meristems are zones of tissue formation, which constitute areas of weakness along the entire culm and provide the basis for rapid shoot elongation. Leaf sheaths clasp the culm preventing the shoot from breaking, ensuring the rigidity to grow erectly and to avoid damage of the meristematic tissue. The mechanical influence of leaf sheaths was investigated in members of Poaceae, Juncaceae, and Cyperaceae in the flowering stage. Mechanical properties of Poa araratica, Bromus erectus, Arrhenatherum elatius (Poaceae), Luzula nivea (Juncaceae), and Carex arctata (Cyperaceae) were determined in three-point bending before and after the removal of leaf sheaths. The presence of leaf sheaths results in smoothing the distribution of flexural rigidity and therefore avoids stress peaks. The achieved maxima of relative contribution of leaf sheaths to entire flexural rigidity ranged from 55% up to 81% for Poaceae, 72% for C. arctata, and 40% for L. nivea. Across the investigated families, the mechanical role of leaf sheaths could be verified as essential for culm stability during development and beyond. Andreas Kempe, Martin Sommer, and Christoph Neinhuis Copyright © 2013 Andreas Kempe et al. All rights reserved. Tue, 04 Dec 2012 15:09:15 +0000 http://www.hindawi.com/journals/jb/2012/679765/ Ardisia crenata is an evergreen shrub with attractive bright red berries. Although this species is usually propagated by seed, the seeds take a long time to germinate with conventional sowing methods. We investigated the germination capacity of seeds and embryos collected in different months and the effects of seed storage conditions, germination temperature, water permeability of the seed coat, and the endosperm on seed germination. Seeds and embryos collected in late September or later showed good germination rates. Seeds germinated more rapidly after longer periods of storage at low temperature (approximately 5°C), and those stored in dry conditions showed lower emergence frequency than those stored in wet conditions. Seeds germinated at 15–30°C, but not at 5–10°C. Removal of the seed coat enhanced water uptake and seed germination. Seeds with various proportions of the removed seed coat were sown on a medium supplemented with sucrose. The germination frequency increased as the size of the remaining endosperm decreased. However, the opposite results were obtained when seeds were sown on a medium without sucrose. We concluded that the optimal temperature of 25°C is the most critical factor for seed germination in A. crenata. Takahiro Tezuka, Hisa Yokoyama, Hideyuki Tanaka, Shuji Shiozaki, and Masayuki Oda Copyright © 2012 Takahiro Tezuka et al. All rights reserved. Wed, 28 Nov 2012 14:23:40 +0000 http://www.hindawi.com/journals/jb/2012/382717/ Conceição Santos, Helena Oliveira, Joanna Deckert, and Jason C. White Copyright © 2012 Conceição Santos et al. All rights reserved. Mon, 05 Nov 2012 16:34:06 +0000 http://www.hindawi.com/journals/jb/2012/510478/ The disparate distribution of apomixis between the major plant lineages is arguably one of the most paradoxical phenomena in plant evolution. Ferns are particularly interesting for addressing this issue because apomixis is more frequent than in any other group of plants. Here, we use a phylogenetic framework to explore some aspects of the evolution of apomixis in ferns and in particular in the polystichoid ferns. Our findings indicate that apomixis evolved several times independently in three different clades of polystichoid ferns. A lineage-wide perspective across ferns indicates a correlation between apomixis and the species richness of lineages; however BiSSE tests did not recover evidence for a correlation of apomixis and diversification rates. Instead, evidence was recovered supporting an association between the establishment of apomixis and reticulate evolution, especially in the establishment of triploid hybrids. Diversification time estimates supported the hypothesis of short living apomictic lineages and indicated a link between the establishment of apomixis and the strengthening of the monsoons caused by the lifting of the Qinghai-Tibetan plateau. In general our results supported the hypothesis for the rare establishment of apomictic lineages, high extinction risks, and low speciation rates. Hong-Mei Liu, Robert J. Dyer, Zhi-You Guo, Zhen Meng, Jian-Hui Li, and Harald Schneider Copyright © 2012 Hong-Mei Liu et al. All rights reserved. Tue, 02 Oct 2012 10:03:20 +0000 http://www.hindawi.com/journals/jb/2012/375829/ A central question in plant regeneration biology concerns the primary driving forces invoking the acquisition of somatic embryogenesis. Recently, the role of micronutrient boron (B) in the initiation and perpetuation of embryogenesis has drawn considerable attention within the scientific community. This interest may be due in part to the bewildering observation that the system-wide induction of embryogenic potential significantly varied in response to a minimal to optimal supply of B (minimal ≤ 0.1 mM, optimal = 0.1 mM). At the cellular level, certain channel proteins and cell wall-related proteins important for the induction of embryogenesis have been shown to be transcriptionally upregulated in response to minimal B supply suggesting the vital role of B in the induction of embryogenesis. At the molecular level, minimal to no B supply increased the endogenous level of auxin, which subsequently influenced the auxin-inducible somatic embryogenesis receptor kinases, suggesting the role of B in the induction of embryogenesis. Also, minimal B concentration may “turn on” other genetic and/or cellular transfactors reported earlier to be essential for cell-restructuring and induction of embryogenesis. In this paper, both the direct and indirect roles of B in the induction of somatic embryogenesis are highlighted and suggested for future validation. Dhananjay K. Pandey, Arvind K. Singh, and Bhupendra Chaudhary Copyright © 2012 Dhananjay K. Pandey et al. All rights reserved. Thu, 09 Aug 2012 09:41:23 +0000 http://www.hindawi.com/journals/jb/2012/310705/ With the continue increase of the world population the requirements for food, freshwater, and fuel are bigger every day. This way an urgent necessity to develop, create, and practice a new type of agriculture, which has to be environmentally sustainable and adequate to the soils, is arising. Among the stresses in plant agriculture worldwide, the increase of soil salinity is considered the major stress. This is particularly emerging in developing countries that present the highest population growth rates, and often the high rates of soil degradation. Therefore, salt-tolerant plants provide a sensible alternative for many developing countries. These plants have the capacity to grow using land and water unsuitable for conventional crops producing food, fuel, fodder, fibber, resin, essential oils, and pharmaceutical products. In addition to their production capabilities they can be used simultaneously for landscape reintegration and soil rehabilitation. This review will cover important subjects concerning saline agriculture and the crop potential of halophytes to use salt-contaminated resources to manage food requirements. Bruno Ladeiro Copyright © 2012 Bruno Ladeiro. All rights reserved. Thu, 19 Jul 2012 13:49:38 +0000 http://www.hindawi.com/journals/jb/2012/369572/ In the recent years, search for better quality of life in urban areas has been provoking an increase in urban agriculture. However, this new way of agriculture can bring risks to human health since this land is highly contaminated, due to anthropogenic activities. This way, lead (Pb) phytotoxicity approach must be taken into consideration since it can be prejudicial to human health through food chain. Pb is a common environmental contaminant, which originate numerous disturbances in plant physiological processes due to the bioacummulation of this metal pollutant in plant tissues. This review, focus on the uptake and interaction of lead by plants and how it can be introduced in food chain. Special attention was taken to address the oxidative stress by lead regarding the effects produced in plant physiological and biochemical processes. Furthermore, the antioxidant defence system was taken into consideration. Phytoremediation is applied on site or chronic polluted soils. This emerging technique is useful to bioaccumulate, degrade or decrease risks associated with contaminants in soils, water or air through the use of hyperaccumulaters. In addition, the impact of nanoparticles in plant science was also focused in this article since some improving properties in plants have been increasingly investigated. Sónia Pinho and Bruno Ladeiro Copyright © 2012 Sónia Pinho and Bruno Ladeiro. All rights reserved. Mon, 02 Jul 2012 08:11:53 +0000 http://www.hindawi.com/journals/jb/2012/219462/ Aluminium (Al) is the third most abundant metallic element in soil but becomes available to plants only when the soil pH drops below 5.5. At those conditions, plants present several signals of Al toxicity. As reported by literature, major consequences of Al exposure are the decrease of plant production and the inhibition of root growth. The root growth inhibition may be directly/indirectly responsible for the loss of plant production. In this paper the most remarkable symptoms of Al toxicity in plants and the latest findings in this area are addressed. Root growth inhibition, ROS production, alterations on root cell wall and plasma membrane, nutrient unbalances, callose accumulation, and disturbance of cytoplasmic Ca2+ homeostasis, among other signals of Al toxicity are discussed, and, when possible, the behavior of Al-tolerant versus Al-sensitive genotypes under Al is compared. Sónia Silva Copyright © 2012 Sónia Silva. All rights reserved. Sun, 17 Jun 2012 17:10:08 +0000 http://www.hindawi.com/journals/jb/2012/751686/ Nanoparticles (NPs) are characterized by their small size (less than 100 nm) and large surface area, which confer specific physicochemical properties as strength, electrical, and optical features. NPs can be derived from natural or anthropic sources, such as engineered or unwanted/incidental NPs. The composition, dimension, and morphology of engineered NPs enable their use in a variety of areas, such as electronic, biomedical, pharmaceutical, cosmetic, energy, environmental, catalysis, and materials science. As nanotechnology is an innovative and scientific growth area with an exponential production, more information is needed concerning the impacts of these nanomaterials (NMs) in the environment and, particularly, in animals/humans health and in plants performance. So, research on NPs as emerging contaminants is therefore a new field in environmental health. This minireview describes, briefly, the NPs characterization and their occurrence in the environment stating air, water, and soil. Finally, particular emphasis is given to the interaction of NPs with plants at different levels: morphology, physiology, and genotoxicity. By analyzing this compiled information, it is evident that research on NPs phytotoxicity is in the beginning, and more comprehensive studies are needed not only on NPs cytotoxicity and genotoxicity but also on the best and the most reliable methods of assessing NPs toxicity. C. Remédios, F. Rosário, and V. Bastos Copyright © 2012 C. Remédios et al. All rights reserved. Sun, 03 Jun 2012 18:09:01 +0000 http://www.hindawi.com/journals/jb/2012/835836/ EF-Tu proteins of plastids, mitochondria, and the cytosolic counterpart EF-1α in plants, as well as EF-Tu proteins of bacteria, are highly conserved and multifunctional. The functions of EF-Tu include transporting the aminoacyl-tRNA complex to the A site of the ribosome during protein biosynthesis; chaperone activity in protecting other proteins from aggregation caused by environmental stresses, facilitating renaturation of proteins when conditions return to normal; displaying a protein disulfide isomerase activity; participating in the degradation of N-terminally blocked proteins by the proteasome; eliciting innate immunity and triggering resistance to pathogenic bacteria in plants; participating in transcription when an E. coli host is infected with phages. EF-Tu genes are upregulated by abiotic stresses in plants, and EF-Tu plays important role in stress responses. Expression of a plant EF-Tu gene confers heat tolerance in E. coli, maize knock-out EF-Tu null mutants are heat susceptible, and over-expression of an EF-Tu gene improves heat tolerance in crop plants. This review paper summarizes the current knowledge of EF-Tu proteins in stress responses in plants and progress on application of EF-Tu for developing crop varieties tolerant to abiotic stresses, such as high temperatures. Jianming Fu, Ivana Momčilović, and P. V. Vara Prasad Copyright © 2012 Jianming Fu et al. All rights reserved. Mon, 28 May 2012 11:49:02 +0000 http://www.hindawi.com/journals/jb/2012/803413/ This paper reviews the adaption to heat and drought stresses in Phaseolus vulgaris, a grain and vegetable crop widely grown in both the Old and New World. Substantial genotypic differences are found in morphophysiological characteristics such as phenology, partitioning, plant-water relations, photosynthetic parameters, and shoot growth, which are related to reproductive responses. The associations between (a) days to podding and leaf water content and (b) the number of pods per plant and seed yield are consistent across different environments and experiments. Leaf water content is maintained by reductions in leaf water potential and shoot extension in response to heat and drought stress. Heat-tolerant cultivars have higher biomass allocation to pods and higher pod set in branches. These traits can be used as a marker to screen germplasm for heat and drought tolerance. In this paper, we briefly review the results of our studies carried out on heat and drought tolerance in the common bean at the Tropical Agriculture Research Front, Ishigaki, Japan. Hide Omae, Ashok Kumar, and Mariko Shono Copyright © 2012 Hide Omae et al. All rights reserved. Sun, 20 May 2012 10:16:15 +0000 http://www.hindawi.com/journals/jb/2012/848614/ With the advent of the industrial revolution, heavy metal contamination has become an ever increasing concern. Thus, it is of major importance to understand the extent of the toxicity in plants and animals and the consequences from the ingestion of contaminated food. Hg is easily modified into several oxidation states, and it can be spread in many ecosystems. Due to the recurrence of Hg pollution and due to the lack of knowledge about the effects of this heavy metal in plants, the aim of the present text is to provide a comprehensive review of the literature regarding Hg phytotoxicity. Raquel Azevedo and Eleazar Rodriguez Copyright © 2012 Raquel Azevedo and Eleazar Rodriguez. All rights reserved. Sun, 20 May 2012 10:14:22 +0000 http://www.hindawi.com/journals/jb/2012/375843/ In the past decades the increased use of chromium (Cr) in several anthropogenic activities and consequent contamination of soil and water have become an increasing concern. Cr exists in several oxidation states but the most stable and common forms are Cr(0), Cr(III) and Cr(VI) species. Cr toxicity in plants depends on its valence state. Cr(VI) as being highly mobile is toxic, while Cr(III) as less mobile is less toxic. Cr is taken up by plants through carriers of essential ions such as sulphate. Cr uptake, translocation, and accumulation depend on its speciation, which also conditions its toxicity to plants. Symptoms of Cr toxicity in plants are diverse and include decrease of seed germination, reduction of growth, decrease of yield, inhibition of enzymatic activities, impairment of photosynthesis, nutrient and oxidative imbalances, and mutagenesis. Helena Oliveira Copyright © 2012 Helena Oliveira. All rights reserved. Tue, 15 May 2012 10:37:32 +0000 http://www.hindawi.com/journals/jb/2012/874256/ Karyomorphological information is one of the most important characters for cytotaxonomy. We described karyomorphology of 14 species of Parnassia in East Asia. They had commonly the resting chromosomes of the simple chromocenter type and the mitotic prophase chromosomes of the proximal type. The somatic chromosome number of 2𝑛=14 was shown in three species, that of 2𝑛=18 was shown in six species, that of 2𝑛=18 or 36 was shown in two species, that of 2𝑛=32 was shown in one species, that of 2𝑛=36 or 36+1∼8 s was shown in one species, and that of 2𝑛=18, 27, 36 or 45 was shown in one species. They were commonly monomodal (gradual) decrease in length from the largest to the smallest chromosomes. However, their absolute chromosome sizes were different from each other. Average chromosome sizes were recognized as three types small (1.21 μm), medium (1.7–2.36 μm), and large (3.1–3.75 μm). Parnassia palustris showed four cytotypes that could be likely cytogeographically correlated with habitats, polyploidy, and sizes of pollen grains. Tsuneo Funamoto and Katsuhiko Kondo Copyright © 2012 Tsuneo Funamoto and Katsuhiko Kondo. All rights reserved. Wed, 09 May 2012 14:28:27 +0000 http://www.hindawi.com/journals/jb/2012/726206/ The incidence of boron (B) toxicity has risen in areas of intensive agriculture close to the Mediterranean sea. The objective of this research was to study the how B toxicity (0.5 and 2 mM B) affects the time course of different indicators of abiotic stress in leaves of two tomato genotypes having different sensitivity to B toxicity (cv. Kosaco and cv. Josefina). Under the treatments of 0.5 and 2 mM B, the tomato plants showed a loss of biomass and foliar area. At the same time, in the leaves of both cultivars, the B concentration increased rapidly from the first day of the experiment. These results were more pronounced in the cv. Josefina, indicating greater sensitivity than in cv. Kosaco with respect to excessive B in the environment. The levels of O2•− and anthocyanins presented a higher correlation coefficient (𝑟>0.9) than did the levels of B in the leaf, followed by other indicators of stress, such as GPX, chlorophyll b and proline (𝑟>0.8). Our results indicate that these parameters could be used to evaluate the stress level as well as to develop models that could help prevent the damage inflicted by B toxicity in tomato plants. Luis M. Cervilla, Begoña Blasco, Juan J. Rios, Miguel A. Rosales, Eva Sánchez-Rodríguez, Maria M. Rubio-Wilhelmi, Luis Romero, and Juan M. Ruiz Copyright © 2012 Luis M. Cervilla et al. All rights reserved. Tue, 24 Apr 2012 11:02:21 +0000 http://www.hindawi.com/journals/jb/2012/217037/ Reactive oxygen species (ROS) are produced as a normal product of plant cellular metabolism. Various environmental stresses lead to excessive production of ROS causing progressive oxidative damage and ultimately cell death. Despite their destructive activity, they are well-described second messengers in a variety of cellular processes, including conferment of tolerance to various environmental stresses. Whether ROS would serve as signaling molecules or could cause oxidative damage to the tissues depends on the delicate equilibrium between ROS production, and their scavenging. Efficient scavenging of ROS produced during various environmental stresses requires the action of several nonenzymatic as well as enzymatic antioxidants present in the tissues. In this paper, we describe the generation, sites of production and role of ROS as messenger molecules as well as inducers of oxidative damage. Further, the antioxidative defense mechanisms operating in the cells for scavenging of ROS overproduced under various stressful conditions of the environment have been discussed in detail. Pallavi Sharma, Ambuj Bhushan Jha, Rama Shanker Dubey, and Mohammad Pessarakli Copyright © 2012 Pallavi Sharma et al. All rights reserved. Mon, 23 Apr 2012 11:32:25 +0000 http://www.hindawi.com/journals/jb/2012/938218/ In agroecosystems, crop yield is reduced by epidemics. At the field scale, epidemiology succeeded knowledge percolation across theory, empirical studies, and recommendations to actors. Achieving similar success at the landscape level requires understanding of ecosystems. The aim of this manuscript is to formalize cyclic epidemics, in which development depends on interaction in space and in time between host plants, pathogens, environment, and human actions. In agroecosystems, human actions exacerbate homogeneities alternating with sharp discontinuities on scales of time and space. The dynamics of cyclic epidemics takes discontinuities into account. This allows decomposing control at the field and at the landscape scales into goals to reach, corresponding to the components of the pluriannual dynamics of epidemics. Articulating disciplinary concepts open the prospect of optimization by identification of one’s potential contributions. Finally, we propose that cyclic epidemics could be controlled by looking for a local solution, in a decentralized manner. Lydia Bousset and Anne-Marie Chèvre Copyright © 2012 Lydia Bousset and Anne-Marie Chèvre. All rights reserved. Thu, 05 Apr 2012 10:41:10 +0000 http://www.hindawi.com/journals/jb/2012/135479/ In the last decades, the use of fungicides in agriculture for fungi diseases control has become crucial. Fungicide research has produced a diverse range of products with novel modes of action. However, the extensive use of these compounds in the agriculture system raises public concern because of the harmful potential of such substances in the environment and human health. Moreover, the phytotoxic effects of some fungicides are already recognized but little is known about the impact of these compounds on the photosynthetic apparatus. This paper presents a comprehensive overview of the literature considering different classes of fungicides and their effects on plant physiology, with particular emphasis on photosynthesis. Maria Celeste Dias Copyright © 2012 Maria Celeste Dias. All rights reserved. Mon, 02 Apr 2012 09:32:45 +0000 http://www.hindawi.com/journals/jb/2012/872875/ Heavy metal (HM) toxicity is one of the major abiotic stresses leading to hazardous effects in plants. A common consequence of HM toxicity is the excessive accumulation of reactive oxygen species (ROS) and methylglyoxal (MG), both of which can cause peroxidation of lipids, oxidation of protein, inactivation of enzymes, DNA damage and/or interact with other vital constituents of plant cells. Higher plants have evolved a sophisticated antioxidant defense system and a glyoxalase system to scavenge ROS and MG. In addition, HMs that enter the cell may be sequestered by amino acids, organic acids, glutathione (GSH), or by specific metal-binding ligands. Being a central molecule of both the antioxidant defense system and the glyoxalase system, GSH is involved in both direct and indirect control of ROS and MG and their reaction products in plant cells, thus protecting the plant from HM-induced oxidative damage. Recent plant molecular studies have shown that GSH by itself and its metabolizing enzymes—notably glutathione S-transferase, glutathione peroxidase, dehydroascorbate reductase, glutathione reductase, glyoxalase I and glyoxalase II—act additively and coordinately for efficient protection against ROS- and MG-induced damage in addition to detoxification, complexation, chelation and compartmentation of HMs. The aim of this review is to integrate a recent understanding of physiological and biochemical mechanisms of HM-induced plant stress response and tolerance based on the findings of current plant molecular biology research. Mohammad Anwar Hossain, Pukclai Piyatida, Jaime A. Teixeira da Silva, and Masayuki Fujita Copyright © 2012 Mohammad Anwar Hossain et al. All rights reserved. Sun, 25 Mar 2012 11:30:42 +0000 http://www.hindawi.com/journals/jb/2012/685427/ Ruta graveolens L. is a medicinal plant used in traditional systems of medicine for treatment of psoriasis, vitiligo, leucoderma, and lymphomas with well-known anti-inflammatory and anticancer properties. Therefore antioxidant potential of R. graveolens (in planta and in vitro) was investigated. As antioxidants present in plant extracts are multifunctional, their activity and mechanism depends on the composition and conditions of the test system. Therefore, the total antioxidant capacity was evaluated using assays that detect different antioxidants: free radical scavenging (DPPH and ABTS), transition metal ion reduction (phosphomolybdenum assay), reducing power, and nitric oxide reduction. Content of furanocoumarin-bergapten in the extracts showed good corelation with free radical scavenging, transition metal reduction and reducing power, while total phenolic content showed good corelation with nitric oxide reduction potential. Antioxidant activity of in vitro cultures was significantly higher compared to in vivo plant material. The present study is the first report on comprehensive study of antioxidant activity of R. graveolens and its in vitro cultures. Renuka Diwan, Amit Shinde, and Nutan Malpathak Copyright © 2012 Renuka Diwan et al. All rights reserved. Wed, 14 Mar 2012 11:46:54 +0000 http://www.hindawi.com/journals/jb/2012/817920/ The highest frequency of polyploidy among plants is considered to occur in the Pteridophytes. In this study, we focused on polyploidy displayed by a specific fern taxon, the genus Pteris L. (Pteridaceae), comprising over 250 species. Cytological data from 106 Pteris species were reviewed. The base number of chromosomes in Pteris is 29. Polyploids are frequently found in Pteris, including triploids, tetraploids, pentaploids, hexaploids, and octoploids. In addition, an aneuploid species, P. deltodon Bak., has been recorded. Furthermore, the relationship between polyploidy and reproductive biology is reviewed. Among these 106 Pteris species, 60% exhibit polyploidy: 22% show intraspecific polyploidy and 38% result from polyploid speciation. Apogamous species are common in Pteris. Diploids are the most frequent among Pteris species, and they can be sexual or apogamous. Triploids are apogamous; tetraploids are sexual or apogamous. Most Pteris species have one to two ploidy levels. The diverse ploidy levels suggest that these species have a complex evolutionary history and their taxonomic problems require further clarification. Yi-Shan Chao, Ho-Yih Liu, Yu-Chung Chiang, and Wen-Liang Chiou Copyright © 2012 Yi-Shan Chao et al. All rights reserved. Wed, 14 Mar 2012 08:08:56 +0000 http://www.hindawi.com/journals/jb/2012/687832/ We present a range of observations on the reproductive morphology, pollination biology and cultivation of Lodoicea maldivica (coco de mer), an endangered species with great ecological, economic and cultural importance. We review the history of study of this charismatic species. Morphological studies of the male inflorescence indicate its importance as a year-round food source to the Seychelles fauna. In situ observations suggest a number of potential biotic and abiotic pollination mechanisms including bees, flies, slugs, and geckos; trigonid bees are identified as the most likely potential natural pollinator. We outline a successful programme for ex situ pollination, germination, and cultivation of the coco de mer, highlighting the importance of temperature, humidity and light levels as well as maintaining an undisturbed environment. In combination with continued protection and monitoring, this advice may aid the future in situ and ex situ conservation of the coco de mer. Stephen Blackmore, See-Chung Chin, Lindsay Chong Seng, Frieda Christie, Fiona Inches, Putri Winda Utami, Neil Watherston, and Alexandra H. Wortley Copyright © 2012 Stephen Blackmore et al. All rights reserved. Mon, 12 Mar 2012 09:50:30 +0000 http://www.hindawi.com/journals/jb/2012/480310/ Present study has been done to investigate artificial interspecific crossability between Japanese Chrysanthemum yoshinaganthum (2𝑛=36) and Chinese C. vestitum (2𝑛=54), which were cultured in vitro and in vivo and characterization of their artificial hybrid chromosomes and type of changes assessed by FISH and GISH. GISH was applied by using biotin-labeled total genomic DNA probe of C. vestitum, which were mixed with blocking DNA of C. yoshinaganthum. Approximately 18 yellow-green colored chromosomes of C. vestitum were detected by the probe, approximately 18 yellow-red- mixed colored chromosomes could be common chromosomes of the two species, and nine chromosomes were relatively red of Ch. yoshinaganthum that were not detected by the probe. The expected average of FISH six signals of 5S rDNA sites and ten of 45S rDNA were observed on the chromosomes of three and six hybrid plants, respectively. Multicolor FISH signals showed unexpected average of seven and 14 yellow signals of 5S rDNA sites on seven and thirteen chromosomes simultaneous with ten and 11 red signals of 45S rDNA sites on ten and 11 chromosomes which were detected by the probes respectively. FISH mapping of the 5S rDNA at terminal sites was detected in hybrid chromosomes, for the first time. Yellow-color signals of the telomeres were detected by the biotin-labeled probe of the PCR-amplified telomeric probe in interphase and terminal sites in metaphase. All chromosomes that showed terminal signals except four chromosomes showed subterminal sites of telomeres indicating the presence of translocations. Magdy Hussein Abd El-Twab and Katsuhiko Kondo Copyright © 2012 Magdy Hussein Abd El-Twab and Katsuhiko Kondo. All rights reserved. Mon, 05 Mar 2012 09:17:45 +0000 http://www.hindawi.com/journals/jb/2012/632547/ Andropogon is a pantropical grass genus comprising 100–120 species and found mainly in the grasslands of Africa and the Americas. In the new world the genus is represented by approximately sixty (diploids or hexaploids) species grouped in three sections. The hexaploid condition occurs only in the Americas and the full process of this origin is still uncertain, although cytogenetic analysis coupled with taxonomic evidence have provided strong support for new hypothesis. Stebbins proposed the first hypothesis suggesting that the origin of polyploidy in species of Andropogon in North America resulted from duplication of the genome of some diploid species, and then by intergeneric crosses with species of a related genus. Since then, numerous studies were performed to clarify the evolutionary history of the genus in America. In this paper, we present a review of cytogenetic studies in the American Andropogon species during the last four decades. Nicolás Nagahama and Guillermo A. Norrmann Copyright © 2012 Nicolás Nagahama and Guillermo A. Norrmann. All rights reserved. Wed, 29 Feb 2012 08:23:12 +0000 http://www.hindawi.com/journals/jb/2012/989272/ In order to study the role of AtKu70 and AtKu80 in Agrobacterium-mediated transformation and gene targeting, plant lines with a T-DNA insertion in AtKu80 or AtKu70 genes were functionally characterized. Such plant lines lacked both subunits, indicating that heterodimer formation between AtKu70 and AtKu80 is needed for the stability of the proteins. Homozygous mutants were phenotypically indistinguishable from wild-type plants and were fertile. However, they were hypersensitive to the genotoxic agent bleomycin, resulting in more DSBs as quantified in comet assays. They had lower end-joining efficiency, suggesting that NHEJ is a critical pathway for DSB repair in plants. Both Atku mutants and a previously isolated Atmre11 mutant were impaired in Agrobacterium T-DNA integration via floral dip transformation, indicating that AtKu70, AtKu80, and AtMre11 play an important role in T-DNA integration in Arabidopsis. The frequency of gene targeting was not significantly increased in the Atku80 and Atku70 mutants, but it was increased at least 10-fold in the Atmre11 mutant compared with the wild type. Qi Jia, Paul Bundock, Paul J. J. Hooykaas, and Sylvia de Pater Copyright © 2012 Qi Jia et al. All rights reserved. Thu, 23 Feb 2012 11:50:56 +0000 http://www.hindawi.com/journals/jb/2012/137037/ Rhizoctonia solani is one of the most destructive pathogens causing foot rot disease on tomato. In this study, the molecular and cellular changes of a partially resistant (Sunny 6066) and a susceptible (Rio Grande) tomato cultivar after infection with necrotrophic soil-borne fungus R. solani were compared. The expression of defense-related genes such as chitinase (LOC544149) and peroxidase (CEVI-1) in infected tomato cultivars was investigated using semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). This method revealed elevated levels of expression for both genes in the partially resistant cultivar compared to the susceptible cultivar. One of the most prominent facets of basal plant defense responses is the formation of physical barriers at sites of attempted fungal penetration. These structures are produced around the sites of potential pathogen ingress to prevent pathogen progress in plant tissues. We investigated formation of lignin, as one of the most important structural barriers affecting plant resistance, using thioglycolic acid assay. A correlation was found between lignification and higher level of resistance in Sunny 6066 compared to Rio Grande cultivar. These findings suggest the involvement of chitinase, peroxidase, and lignin formation in defense responses of tomato plants against R. solani as a destructive pathogen. Parissa Taheri and Saeed Tarighi Copyright © 2012 Parissa Taheri and Saeed Tarighi. All rights reserved. Mon, 20 Feb 2012 11:18:00 +0000 http://www.hindawi.com/journals/jb/2012/389247/ When field tests of transgenic plants are precluded by practical containment concerns, manipulative experiments can detect potential consequences of crop-wild gene flow. Using topical sprays of bacterial Bacillus thuringiensislarvicide (Bt) and larval additions, we measured fitness effects of reduced herbivory on Brassica rapa (wild mustard) and Raphanus sativus (wild radish). These species represent different life histories among the potential recipients of Bt transgenes from Bt cole crops in the US and Asia, for which rare spontaneous crosses are expected under high exposure. Protected wild radish and wild mustard seedlings had approximately half the herbivore damage of exposed plants and 55% lower seedling mortality, resulting in 27% greater reproductive success, 14-day longer life-spans, and 118% more seeds, on average. Seed addition experiments in microcosms and in situ indicated that wild radish was more likely to spread than wild mustard in coastal grasslands. D. K. Letourneau and J. A. Hagen Copyright © 2012 D. K. Letourneau and J. A. Hagen. All rights reserved. Wed, 15 Feb 2012 13:18:32 +0000 http://www.hindawi.com/journals/jb/2012/985298/ Reactive oxygen species (ROS) are astonishingly versatile molecular species and radicals that are poised at the core of a sophisticated network of signaling pathways of plants and act as core regulator of cell physiology and cellular responses to environment. ROS are continuously generated in plants as an inevitable consequence of redox cascades of aerobic metabolism. In one hand, plants are surfeited with the mechanism to combat reactive oxygen species, in other circumstances, plants appear to purposefully generate (oxidative burst) and exploit ROS or ROS-induced secondary breakdown products for the regulation of almost every aspect of plant biology, from perception of environmental cues to gene expression. The molecular language associated with ROS-mediated signal transduction, leading to modulation in gene expression to be one of the specific early stress response in the acclamatory performance of the plant. They may even act as “second messenger” modulating the activities of specific proteins or expression of genes by changing redox balance of the cell. The network of redox signals orchestrates metabolism for regulating energy production to utilization, interfering with primary signaling agents (hormones) to respond to changing environmental cues at every stage of plant development. The oxidative lipid peroxidation products and the resulting generated products thereof (associated with stress and senescence) also represent “biological signals,” which do not require preceding activation of genes. Unlike ROS-induced expression of genes, these lipid peroxidation products produce nonspecific response to a large variety of environmental stresses. The present review explores the specific and nonspecific signaling language of reactive oxygen species in plant acclamatory defense processes, controlled cell death, and development. Special emphasis is given to ROS and redox-regulated gene expression and the role of redox-sensitive proteins in signal transduction event. It also describes the emerging complexity of apparently contradictory roles that ROS play in cellular physiology to ascertain their position in the life of the plant. Soumen Bhattacharjee Copyright © 2012 Soumen Bhattacharjee. All rights reserved. Thu, 09 Feb 2012 12:13:38 +0000 http://www.hindawi.com/journals/jb/2012/936950/ We evaluated the effects of cadmium on phenolic composition of Erica andevalensis, an endemic protected heather that grows in mine affected soils. Plants cultivated under laboratory-controlled conditions were exposed to acute doses of cadmium to investigate the mechanisms this species possesses to survive in the presence of toxic metals in its natural habitat. Cadmium increased the total levels of phenolics and flavonoids compounds, and the total antioxidant capacity. Cinnamic acid derivatives, epicatechin, and rutin were increased in the presence of cadmium when applied in levels that did not alter the ratio of chlorophylls. Phenolic compounds play an important role in the metabolism of E. andevalensis to survive in heavy metal polluted soils. Belén Márquez-García, M. Ángeles Fernández-Recamales, and Francisco Córdoba Copyright © 2012 Belén Márquez-García et al. All rights reserved. Mon, 06 Feb 2012 10:04:16 +0000 http://www.hindawi.com/journals/jb/2012/737035/ Abiotic stress adversely affects the growth of grapevine plants. In order to study the early expression changes of genes particularly involved in signal transduction upon salt and drought stresses in grapevines, ESTs derived from a suppressive subtractive hybridization approach (SSH) were selected for expression studies. We were particularly interested in the expression behaviour of the MAP kinase cDNA clone identified by differential screening of the salt-stressed SSH libraries. Interestingly, VvMAP kinase transcript showed a differential expression towards salt and drought treatment in the salt tolerant cultivar Razegui. The upregulation of this transcript was confirmed by RNA blot analysis. Our results revealed that the VvMAP kinase gene could be classified as an osmotic stress responsive gene as its expression was induced by salinity and drought. Furthermore, our study provides the basis for future research on the diverse signaling pathways mediated by MAPKs in grapevine. Samia Daldoul, Michael Hoefer, and Ahmed Mliki Copyright © 2012 Samia Daldoul et al. All rights reserved.