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Probing poplar's proteome
As the effects of climate change become clearer, plant breeders have turned their attention to plants that are able to survive or even thrive in temperatures that would be harmful to many species. One such heat-adapted species is Populus euphratica. It is described by Ferreira et al. (Portugal–Scandinavia, pp. 361–377) as a pioneer species growing along riversides in natural desert ecosystems and can survive at temperatures up to 50 ˚C provided it has a water supply. Experiments to determine membrane integrity (as indicated by rate of electrolyte leakage) indicate that the lethal temperature lies between 50 and 55 ˚C. Such a plant is an ideal target for the breeder, but which genes should be the focus of attention? The authors have used a genome-wide proteomics approach to start to answer this question. This demands a large amount of work and essentially involves using 2D gel electrophoresis to fractionate proteins from control and heat-stressed leaves. The gels were scanned and the intensity of each spot determined by image analysis. The numbers generated by this type of experiment are large: the authors were able identify a total of 1355 different proteins, of which 45 % showed changes in abundance of more than 50 % following exposure to heat stress. Individual proteins were then identified by cutting spots from the gels and obtaining a partial sequence for each spot by MALDI-TOF. This was successful for 82 % of the protein spots and thus provided an extensive picture of the major changes in protein expression associated with heat stress. The data set is too extensive for detailed comment here; readers are referred to the paper itself for the thorough presentation of these results. The next task, of course, is to determine which of these changes is most important for the heat adaptation of P. euphratica. Then the plant breeders can really get to work!
Professor J. A. Bryant
University of Exeter, UK
j.a.bryant{at}exeter.ac.uk
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