Transcriptional responses of winter barley to cold indicate nucleosome remodelling as a specific feature of crown tissues

Abstract

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.

Low temperature tolerance in plants: Changes at the protein level

“…In fact, the cold acclimatisation process in barley has been mainly studied from a genomic and transcriptomic point of view. Transcriptional responses of winter barley to various periods of low (above and below zero) temperatures were recently evaluated by Janská et al (2011). Their results interestingly revealed that during the cold acclimation process, the production of ice nucleation substances in both the leaf and the crown was suppressed, correlating with the rapid up-regulation of genes encoding the major antifreeze (chitinases, glucanases, thaumatin-like proteins) and ice recrystallization inhibition proteins.…”

“…Likewise, Wang et al (2004) found a close correlation between levels of antifreeze proteins (CLP and TLP) and degrees of freezing tolerance and it has been revealed that the expression of antifreeze genes is significantly induced by cold acclimation. In addition, during the cold and sub-zero acclimation various heat-shock proteins (HSPs) were also induced in the leaf (Janská et al, 2011). Moreover, in this tissue cold acclimation resulted in the up-regulation of sucrose degradation enzymes, whereas, in the crown, the induction of the expression of sucrose transporter genes, rather than those of the sucrose degradation machinery, was observed.…”

Advances in detection of stress tolerance in plants through metabolomics approaches

“…Metabolite fingerprints to cold stress were obtained for Drosophila melanogaster individuals (Korn et al, 2010) and showed that the strategies to cold adaptation might be the same within all members of the kingdom. Janská et al (2011) confirmed all the significant metabolic variations, stirring in cold acclimatization, reenforcing the impression that the combination of cryoprotectant molecules is of great valve (Guy et al, 2008). Amongst these cryo-protectans, sugars, sugar alcohols and proline were exposed to be of higher significance.…”

Nonsense-mediated decay of sucrose synthase 1 mRNA with induced premature chain termination codon during cold acclimation in winter wheat

“…Janská et al (2011) also observed only a marginal effect of low temperature on the expression of genes involved in sucrose/starch metabolism in the crown of winter barley. They hypothesized that sucrose can be exported rather than cleaved into fructose and glucose, as the few genes that were significantly upregulated in the crown were indeed sucrose transporters.…”

“…Ss2 was expressed in the endosperm only, whereas Ss1 mRNA was expressed in both roots and leaves (Martinez de Ilarduya et al, 1993). Sucrose synthase activity increases during cold acclimation in leaves (Crespi et al, 1991;Sasaki et al, 2001;Janská et al, 2011). In wheat exposed to low temperature, Ss1 activity was found to be higher in the winter wheat cultivar Monopol than in the spring wheat cultivar Katepwa (Savitch et al, 2000).…”