A high quality international journal   Physiologia Plantarum is SPPS's international journal published by Wiley-Blackwell. It is dedicated to original research that advances our understanding of the primary physiological and molecular mechanisms governing plant development, growth and productivity.   Physiologia Plantarum presented its new cover January 2005. Graphic by Gorm Palmgren. In addition to regular articles, Physiologia Plantarum also publishes Minireviews and Technical Focus papers. Moreover, Special Issues that contain several reviews focusing on recent advances in a selected field are published several times every year. Physiologia Plantarum ranks as an impressive #28 among the 172 most cited international plant science journals. The impact factor is presently 2.708 and rising. Editor-in-Chief Vaughan Hurry, Associate Professor at Umeå Plant Science Centre in Sweden, and the journal representatives have recently taken several initiatives in order to make the journal even better for both readers and authors. Read about these efforts in two recent aricles in SPPS Newsletter by clicking here and here. You can find more information about Physiologia Plantarum on the journals official website.   Read featured articles for free   An article of general interest from Physiologia Plantarum is highlighted and commented in each issue of SPPS Newsletter. Below you can see our recent pickings and the original article is freely available from the publisher, Blackwell, by simply clicking the reference!   Function of mitochondria in desiccation tolerance When seeds mature they loose most protoplasmic water and eventually holds no free water in the cells. This calls for a number of protective mechanisms to protect the structure and function of macromolecules and membranes, including the mitochondria whose function is imperative for the seed's ability to germinate after rehydration. In order to study this, Song-Quan Song from The Chinese Academy of Sciences in Beijing, China investigated mitochondrial function and structure of pea (Pisum sativum) seeds during germination after various sequential imbibition, dehydration and re-imbibition treatments. It turned out that while the outer mitochondrial membrane kept its integrity in all treatments, integrity of the inner mitochondrial membrane and cytochrome respiratory function was more labile after prolonged imbibition (more than 12 hours) and this correlated with decreased desiccation tolerance. Imbibition in the presence of CaCl2, however, increased desiccation tolerance, suggesting the requirement for Ca2+ in mitochondrial membrane structure and function. Read full article free: Wang et al (January 2012) Physiologia Plantarum 144: 20   DNA methylation is a marker of flowering Induction of flowering in azalea (Rhododendron spp.) is associated with changes in DNA methylation levels and these epigenetic alterations seem to be markers of floral bud development. This was shown by Maria Jesus Canal from Universidad de Oviedo in Spain in an experiment where manipulations of photoperiod and temperature were used to promote flowering. Within days after the shift from long days to short days there was a substantial decrease in overall DNA methylation, eventually amounting to almost 50%. Subsequently, however, methylation increased sharply and climbed to a level approximately 25% above the initial value. This pattern of fluctuations in the DNA methylation level followed floral development and was consistent between different cultivars and plants grown under various flower induction conditions. The authors suggest that measurements of DNA methylation can be used as a marker of flower development in commercial production of azalea and probably also other ornamentals. Read full article free: Meijon et al (September 2011) Physiologia Plantarum 143: 82   Protecting trees from stress with genetic modification Salinity, drought, temperature, chemical toxicity, wind and gravity are among the many abiotic stresses that challenge trees and other plants. With the ability to transform a growing number of tree species including poplar (Populus), Eucalyptus, birch (Betula), pine (Pinus) and spruce (Picea), scientists are now making progress to elucidate the complex cascades of gene expression in abiotic stress responses, in order to use this knowledge for generation of trees that can better cope with the environmental changes we are experiencing. In a minireview, Yuriko Osakabe from University of Tokyo examines the current efforts and progress. Poplar and eucalyptus are by far the most used experimental trees and popular traits include resistance to drought, salt and cold. In addition, genetic manipulation of lignin content and composition can not only increase the commercial value of woody biomass but also improve resistance to water stress. Read full article free: Osakabe et al (June 2011) Physiologia Plantarum 142: 105   Epigenetic markers of flowering Since floral quality is the most important trait in ornamental plant industry it is very desirable to be able to control and predict floral capacity. Plant growth regulators - and in particular growth retarding gibberellin (GA) inhibitors - are widely used to promote flowering, so Isabel Feito from the Agri-food Research and Development Service (SERIDA) and co-workers from Universidad de Oviedo, both in Asturias, Spain, wanted to identify markers that could indicate how azalea (Rhododendron sp) plants reacted to the treatment. Application of GA inhibitors during the vegetative phase affected the levels of polyamines, GAs and cytokinins throughout subsequent bud development. Notable changes in the corresponding level of global DNA methylation was also observed and DNA methylation is known to be part of the epigenetic control of flower development. During the reorganization phase in the fall, where global DNA demythylation is generally observed, treatment with GA inhibitors led to substantial further demethylation, while methylation levels during flowering in late winter was higher in treated plants than in untreated controls. Based on these results, Isabel Feito suggests that levels of DNA methylation, polyamines, GAs and cytokinins can be used as predictive markers of floral capacity in azalea. Read full article free: Monica Meijon et al (March 2011) Physiologia Plantarum 141: 276-288   Tomato math A mathematical model that describes the viscoelastic behaviour of tomatoes has been developed by Antonio Heredia and coworkers from Universidad de Malaga in Spain. The main biochemical feature of tomato skin is the cuticle, which is basically composed of soluble wax and insoluble inter-esterified hydroxyalkanoic acids forming a high-molecular weight biopolymer. The cuticle is of great commercial importance as it offers mechanical resistance to deformation and influence post-harvest shelf life and quality. These traits, however, depend on parameters like temperature and hydration that can be controlled during post-harvest handling of the fruits. The model combines mechanical data from previous analysis of tomatoes kept under different conditions and integrates an elastic and a viscous element to describe the mechanical behaviour of isolated cuticle. The model obtained a good fit between experimental and modelled data, and e.g. correctly predicted a reduced resistance to breakage under humid conditions. Read full article free: Lopez-Casado et al (September 2010) Physiologia Plantarum 140: 79-88   Transcriptome reveals phosphate responses Microarrays are increasingly being used for global expression studies and over the last few years this has been used to build up substantial information about the plant transcriptome. Using internet-based data ressources from previous analysis on Arabidopsis thaliana, Danish researchers have dissected the complex regulatory network involved in responses to phosphate deprivation. Tom Hamborg Nielsen and co-workers from University of Copenhagen and Aalborg University evaluated the functional relationship between several transcription factors, microRNAs (miRNAs) and feedback loops that contribute to keep P-homeostasis. The authors propose a model for the complex coordinated responses to phosphate starvation, which affect all parts of the plant and include Pi-signalling miRNAs that are transported via the phloem. However, the model still lacks any sensor of P-status, since the precise role of several recent candidates for this crucial function still needs to be verified. Read full article free: Nilsson et al (June 2010) Physiologia Plantarum 139: 129-143   Shedding light in the canopy Since plants get most of their light from above, photosynthetic activity is highest in the upper part of the canopy. Applying light directly into the canopy might, accordingly, contribute to a more uniform photosynthetic profile and could potentially increase overall photosynthesis leading to higher yield of crops. This hypothesis has now been tested by Dutch researchers from Wageningen University in the Netherlands. They supplied cucumber plants grown in the greenhouse with 38% of their light from LEDs within the canopy and compared them with controls that got all the light from above. Light from within the canopy significantly increased photosynthesis in the lower leaf layers, however, this was not followed by a concomitant increase in overall biomass and fruit yield. This was apparently caused by a more stunted growth when less light came from above and because the LEDs seemingly caused the leaves to curl and thus reduced light interception. Read full article free: Trouwborst et al (March 2010) Physiologia Plantarum 138: 289Ð300   Design and technical solution © 2005 Palmgren kommunikation.