As sessile organisms, plants are unable to escape from the many abiotic and biotic factors that cause a departure from optimal conditions of growth and development. Low temperature represents one of the most harmful abiotic stresses affecting temperate plants. These species have adapted to seasonal variations in temperature by adjusting their metabolism during autumn, increasing their content of a range of cryo-protective compounds to maximise their cold tolerance. Some of these molecules are synthesised de novo. The down-regulation of some gene products represents an additional important regulatory mechanism. Ways in which plants cope with cold stress are described, and the current state of the art with respect to both the model plant Arabidopsis thaliana and crop plants in the area of gene expression and metabolic pathways during low-temperature stress are discussed.

Background: Molecular marker technologies are undergoing a transition from largely serial assays measuring DNA fragment sizes to hybridization-based technologies with high multiplexing levels. Diversity Arrays Technology (DArT) is a hybridization-based technology that is increasingly being adopted by barley researchers. There is a need to integrate the information generated by DArT with previous data produced with gel-based marker technologies. The goal of this study was to build a high-density consensus linkage map from the combined datasets of ten populations, most of which were simultaneously typed with DArT and Simple Sequence Repeat (SSR), Restriction Enzyme Fragment Polymorphism (RFLP) and/or Sequence Tagged Site (STS) markers.

Amplified fragment length polymorphism (AFLP) analysis has been used to analyse mainly 83 Czech isolates of Pyrenophora teres, P. graminea, P. tritici-repentis and Helminthosporium sativum. Each species had distinct AFLP profiles. Using 19 primer combinations 948 polymorphic bands were detected. All main clusters in dendrogram correspond to the studied species. Even the two forms of P. teres -P. teres f. teres (PTT) and P. teres f. maculata (PTM) -formed different clusters. Genetic diversity, with regard to the locality and the year of the sample's collection, was analysed separately within the AFLP-based dendrogram cluster of PTT and PTM. Unweighted pairgroup method (UPGMA) analysis of the 37 isolates of PTT and 30 isolates of PTM, using 469 polymorphic bands, showed that the variability seemed to have been influenced more by the year of sampling than by the geographic origin of the isolate. The presence of intermediate haplotypes with a relatively high number of shared markers between the two groups indicated that hybridization between the forms of P. teres could happen, but it is probably often overlapped by selection pressure or genetic drift.www.blackwell-synergy.com

This document provides guidance for the agronomic and phenotypic characterisation of genetically modified (GM) plants and clarifies the EFSA GMO Panel?s view on how agronomic and phenotypic data support the risk assessment of GM plants. Specific recommendations are given on (1) the selection of sites and test materials; (2) the quality and design of field trials; (3) the selection of relevant agronomic and phenotypic endpoints; and (4) data analysis. The guidance proposes a comprehensive and harmonised approach for the agronomic and phenotypic characterisation of GM plants, which should ensure the best use of agronomic and phenotypic data for the comparative analysis of GM plants and derived food and feed products, and for their food and feed and environmental risk assessment.publishersversionNon peer reviewe

We report a series of microarray-based comparisons of gene expression in the leaf and crown of the winter barley cultivar Luxor, following the exposure of young plants to various periods of low (above and below zero) temperatures. A transcriptomic analysis identified genes which were either expressed in both the leaf and crown, or specifically in one or the other. Among the former were genes responsible for calcium and abscisic acid signalling, polyamine synthesis, late embryogenesis abundant proteins and dehydrins. In the crown, the key organ for cereal overwintering, cold treatment induced transient changes in the transcription of nucleosome assembly genes, and especially H2A and HTA11, which have been implicated in cold sensing in Arabidopsis thaliana. In the leaf, various heat-shock proteins were induced. Differences in expression pattern between the crown and leaf were frequent for genes involved in certain pathways responsible for osmolyte production (sucrose and starch, raffinose, γ-aminobutyric acid metabolism), sugar signalling (trehalose metabolism) and secondary metabolism (lignin synthesis). The action of proteins with antifreeze activity, which were markedly induced during hardening, was demonstrated by a depression in the ice nucleation temperature.Electronic supplementary materialThe online version of this article (doi:10.1007/s10142-011-0213-8) contains supplementary material, which is available to authorized users.