Hot off the presses! Sep 01 Trends Plant Sci

The Sep 01 issue of the Trends Plant Sci is now up on Pubget (About Trends Plant Sci): if you're at a subscribing institution, just click the link in the latest link at the home page. (Note you'll only be able to get all the PDFs in the issue if your institution subscribes to Pubget.)

Latest Articles Include:

• Editorial Board
  - Trends Plant Sci 16(9):i (2011)
  
• AuxV: a database of auxin transport velocities
  - Trends Plant Sci 16(9):461-463 (2011)
  One of the most widely used techniques to quantify polar auxin transport is the measurement of auxin speed. To date there have been more than 90 published reports of auxin speed in 44 species. We have collected available speed measurements into a database, along with information on plant growth conditions and growth rate. Measured auxin speeds have a range of 1.2–18 mm/h, and show notable correlations with organ type, growth rate, and plant clade.
• Understanding shoot branching by modelling form and function
  - Trends Plant Sci 16(9):464-467 (2011)
  Shoot branching plays a pivotal role in the development of the aboveground plant structure. Therefore, to understand branching in relation to the environment, it is not only necessary to integrate the knowledge on mechanisms that regulate branching at multiple levels of biological organisation, but also to include plant structure explicitly. To this end, we propose the application of an established methodology called functional–structural plant modelling.
• Prototype cell-to-cell auxin transport mechanism by intracellular auxin compartmentalization
  - Trends Plant Sci 16(9):468-475 (2011)
  Carrier-dependent, intercellular auxin transport is central to the developmental patterning of higher plants (tracheophytes). The evolution of this polar auxin transport might be linked to the translocation of some PIN auxin efflux carriers from their presumably ancestral localization at the endoplasmic reticulum (ER) to the polar domains at the plasma membrane. Here we propose an eventually ancient mechanism of intercellular auxin distribution by ER-localized auxin transporters involving intracellular auxin retention and switch-like release from the ER. The proposed model integrates feedback circuits utilizing the conserved nuclear auxin signaling for the regulation of PIN transcription and a hypothetical ER-based signaling for the regulation of PIN-dependent transport activity at the ER. Computer simulations of the model revealed its plausibility for generating auxin channels and localized auxin maxima highlighting the possibility of this alternative mechanism for po! lar auxin transport.
• Towards food, feed and energy crops mitigating climate change
  - Trends Plant Sci 16(9):476-480 (2011)
  Agriculture is an important source of anthropogenic emissions of the greenhouse gases (GHG), methane (CH4) and nitrous oxide (N2O), and crops can affect the microbial processes controlling these emissions in many ways. Here, we summarize the current knowledge of plant–microbe interactions in relation to the CH4 and N2O budgets and show how this is promoting new generations of crop cultivars that have the potential to mitigate GHG emissions for future agricultural use. The possibility of breeding low GHG-emitting cultivars is a paradigm shift towards sustainable agriculture that balances climate change and food and bioenergy security.
• Expression level polymorphisms: heritable traits shaping natural variation
  - Trends Plant Sci 16(9):481-488 (2011)
  Natural accessions of many species harbor a wealth of genetic variation visible in a large array of phenotypes. Although expression level polymorphisms (ELPs) in several genes have been shown to contribute to variation in diverse traits, their general impact on adaptive variation has likely been underestimated. At present, ELPs have predominantly been correlated to quantitative trait loci (eQTLs) that occupy central hubs in signaling networks, which pleiotropically affect numerous traits. To increase the sensitivity of detecting minor effect eQTLs or those that act in a trait-specific manner, we emphasize the need for more systematic approaches. This requires, but is not limited to, refining experimental designs such as reduction of tissue complexity and combinatorial methods including a priori defined networks.
• Protein degradation – an alternative respiratory substrate for stressed plants
  - Trends Plant Sci 16(9):489-498 (2011)
  In cellular circumstances under which carbohydrates are scarce, plants can metabolize proteins and lipids as alternative respiratory substrates. Respiration of protein is less efficient than that of carbohydrate as assessed by the respiratory quotient; however, under certain adverse conditions, it represents an important alternative energy source for the cell. Significant effort has been invested in understanding the regulation of protein degradation in plants. This has included an investigation of how proteins are targeted to the proteosome, and the processes of senescence and autophagy. Here we review these events with particular reference to amino acid catabolism and its role in supporting the tricarboxylic acid cycle and direct electron supply to the ubiquinone pool of the mitochondrial electron transport chain in plants.
• 12C/13C fractionations in plant primary metabolism
  - Trends Plant Sci 16(9):499-506 (2011)
  Natural 13C abundance is now an unavoidable tool to study ecosystem and plant carbon economies. A growing number of studies take advantage of isotopic fractionation between carbon pools or 13C abundance in respiratory CO2 to examine the carbon source of respiration, plant biomass production or organic matter sequestration in soils. 12C/13C isotope effects associated with plant metabolism are thus essential to understand natural isotopic signals. However, isotope effects of enzymes do not influence metabolites separately, but combine to yield a 12C/13C isotopologue redistribution orchestrated by metabolic flux patterns. In this review, we summarise key metabolic isotope effects and integrate them into the corpus of plant primary carbon metabolism.
• Adenine nucleotide transport in plants: much more than a mitochondrial issue
  - Trends Plant Sci 16(9):507-515 (2011)
  Adenine nucleotides play a vital role in plant metabolism and physiology, essentially representing the major energy currency of the cell. Heterotrophic cells regenerate most of the ATP in mitochondria, whereas autotrophic cells also possess chloroplasts, representing a second powerhouse for ATP regeneration. Even though the synthesis of these nucleotides is restricted to a few locations, their use is nearly ubiquitous across the cell and thereby highly efficient systems are required to transport these molecules into and out of different compartments. Here, we discuss the location, biochemical characterization and evolution of corresponding transport systems in plants. We include recent scientific findings concerning organellar transporters from plants and algae and also focus on the physiological importance of adenine nucleotide exchange in these cells.