Advances in Botany http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. In Vitro Mass Multiplication and Assessment of Genetic Stability of In Vitro Raised Artemisia absinthium L. Plants Using ISSR and SSAP Molecular Markers Wed, 13 Aug 2014 08:08:37 +0000 http://www.hindawi.com/journals/abot/2014/727020/ The present investigations were made attempting to develop a rapid, reliable, and reproducible in vitro regeneration protocol for Artemisia absinthium L., a medicinal plant of Kashmir Himalayas. Out of several auxin-cytokinin combinations tested, Murashige and Skoog’s (MS) medium supplemented with 0.5 mgL−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.5 mgL−1 kinetin (Kn) was found to be the best for the callus induction. On the other hand, 4.5 mgL−1 6-benzylaminopurine (BAP) and 0.5 mgL−1 1-α-naphthaleneacetic acid (NAA) in the medium resulted in maximum shoot induction from the callus. Similarly, BAP and NAA at a concentration of 1.5 mgL−1 and 0.5 mgL−1, respectively, proved to be the best for the multiple shoot induction from nodal explants. Numerous shoots were obtained from nodal explants after third subculture. In vitro rooting was maximum on medium containing indole-3-butyric acid (IBA) at 0.5 mgL−1. The genetic stability of the in vitro raised plants of Artemisia absinthium was assessed using the intersimple sequence repeat (ISSR) and sequence-specific amplification polymorphism (SSAP) molecular markers. Both markers were able to detect the somaclonal variations in the callus regenerated plants, while no variation was detected in the plants regenerated from the nodal explants. SSAP has been found to be more useful in detection of variability as compared to ISSR molecular marker. The results of present study concluded that the direct regeneration protocol will be useful for the production of true to type plants of this medicinally important plant. This will go a long way in reducing the pressure on the natural populations for the secondary metabolite production, especially for extraction of essential oils. B. Kour, G. Kour, S. Kaul, and M. K. Dhar Copyright © 2014 B. Kour et al. All rights reserved. Aflatoxin Resistance in Maize: What Have We Learned Lately? Mon, 04 Aug 2014 05:30:35 +0000 http://www.hindawi.com/journals/abot/2014/352831/ Aflatoxin contamination of maize grain is a huge economic and health problem, causing death and increased disease burden in much of the developing world and income loss in the developed world. Despite the gravity of the problem, deployable solutions are still being sought. In the past 15 years, much progress has been made in creating resistant maize inbred lines; mapping of genetic factors associated with resistance; and identifying possible resistance mechanisms. This review highlights this progress, most of which has occurred since the last time a review was published on this topic. Many of the needs highlighted in the last reviews have been addressed, and several solutions, taken together, can now greatly reduce the aflatoxin problem in maize grain. Continued research will soon lead to further solutions, which promise to further reduce and even eliminate the problem completely. Marilyn L. Warburton and W. Paul Williams Copyright © 2014 Marilyn L. Warburton and W. Paul Williams. All rights reserved. Function and Regulation of the Plant COPT Family of High-Affinity Copper Transport Proteins Mon, 21 Jul 2014 09:43:50 +0000 http://www.hindawi.com/journals/abot/2014/476917/ Copper (Cu) is an essential micronutrient for all eukaryotes because it participates as a redox active cofactor in multiple biological processes, including mitochondrial respiration, photosynthesis, oxidative stress protection, and iron (Fe) transport. In eukaryotic cells, Cu transport toward the cytoplasm is mediated by the conserved CTR/COPT family of high-affinity Cu transport proteins. This outlook paper reviews the contribution of our research group to the characterization of the function played by the Arabidopsis thaliana COPT1–6 family of proteins in plant Cu homeostasis. Our studies indicate that the different tissue specificity, Cu-regulated expression, and subcellular localization dictate COPT-specialized contribution to plant Cu transport and distribution. By characterizing lack-of-function Arabidopsis mutant lines, we conclude that COPT1 mediates root Cu acquisition, COPT6 facilitates shoot Cu distribution, and COPT5 mobilizes Cu from storage organelles. Furthermore, our work with copt2 mutant and COPT-overexpressing plants has also uncovered Cu connections with Fe homeostasis and the circadian clock, respectively. Future studies on the interaction between COPT transporters and other components of the Cu homeostasis network will improve our knowledge of plant Cu acquisition, distribution, regulation, and utilization by Cu-proteins. Sergi Puig Copyright © 2014 Sergi Puig. All rights reserved. Towards Understanding Extracellular ROS Sensory and Signaling Systems in Plants Sun, 01 Jun 2014 08:11:37 +0000 http://www.hindawi.com/journals/abot/2014/538946/ Reactive Oxygen Species (ROS) are ubiquitous metabolites in all aerobic organisms. Traditionally ROS have been considered as harmful, accidental byproducts of cellular functions involving electron transport chains or electron transfer. However, it is now recognized that controlled production of ROS has significant signaling functions, for example, in pathogen defense, in the regulation of stomatal closure, or in cell-to-cell signaling. ROS formation in subcellular compartments is critical to act as “alarm” signal in the response to stress, and the concept of ROS as primarily signaling substances has emerged. The involvement of ROS in several developmental and inducible processes implies that there must be coordinated function of signaling network(s) that govern ROS responses and subsequent processes. The air pollutant ozone can be used as a useful tool to elucidate the function of apoplastic ROS: O3 degrades in cell wall into various ROS which are interpreted as ROS with signaling function inducing downstream responses. We have used ozone as a tool in mutant screens and transcript profiling-reverse genetics to identify genes involved in processes related to the signaling function of ROS. We review here our recent findings in the elucidation of apoplastic ROS sensing, signaling, and interaction with various symplastic components. Saijaliisa Kangasjärvi and Jaakko Kangasjärvi Copyright © 2014 Saijaliisa Kangasjärvi and Jaakko Kangasjärvi. All rights reserved. Plant Phenotypic Plasticity in Response to Environmental Factors Tue, 22 Apr 2014 11:28:46 +0000 http://www.hindawi.com/journals/abot/2014/208747/ Plants are exposed to heterogeneity in the environment where new stress factors (i.e., climate change, land use change, and invasiveness) are introduced, and where inter- and intraspecies differences may reflect resource limitation and/or environmental stress factors. Phenotypic plasticity is considered one of the major means by which plants can cope with environmental factor variability. Nevertheless, the extent to which phenotypic plasticity may facilitate survival under environmental condition changes still remains largely unknown because results are sometimes controversial. Thus, it is important to identify plant functional traits in which plasticity may play a determinant role in plant response to global change as well as on the ecological consequences at an ecosystem level for the competition between wild and invasive species, considering that species with a greater adaptive plasticity may be more likely to survive in novel environmental conditions. In the near future, it will be important to increase long-term studies on natural populations in order to understand plant response to environmental factor fluctuations including climate change. There is the necessity to analyze variations at phenotypic and genetic levels for the same species and, in particular, for endemic and rare species because these could have drastic effects at an ecosystem level. Loretta Gratani Copyright © 2014 Loretta Gratani. All rights reserved. Phytomelatonin: Discovery, Content, and Role in Plants Thu, 10 Apr 2014 00:00:00 +0000 http://www.hindawi.com/journals/abot/2014/815769/ Melatonin (N-acetyl-5-methoxytryptamine) is an indolic compound derived from tryptophan. Usually identified as a neurotransmitter or animal hormone, this compound was detected in plants in 1995. Interest in knowing the melatonin content of plants and its possible role therein is growing, as indicated by the increasing number of related publications. Melatonin is present in all plant species studied, with large variations in its level depending on the plant organ or tissue. It seems to be more abundant in aromatic plants and in leaves than in seeds. Regarding its physiological function in plants, melatonin shows auxin activity and is an excellent antioxidant, regulating the growth of roots, shoots, and explants, activating seed germination and rhizogenesis (lateral- and adventitious-roots), and delaying induced leaf senescence. Its ability to strengthen plants subjected to abiotic stress such as drought, cold, heat, salinity, chemical pollutants, herbicides, and UV radiation makes melatonin an interesting candidate for use as a natural biostimulating substance for treating field crops. Marino B. Arnao Copyright © 2014 Marino B. Arnao. All rights reserved.