Salinity strongly limits soil fertility in the Mediterranean region. Thanks to its fast growth and biomass production, Populus alba L. is an interesting forest species for Mediterranean ecosystems and its native germplasm can provide genetic resources to improve tolerance to drought and salinity stress. The objective of this study was to investigate the mechanisms that underlie the variability of response to salinity stress within this species. Two Populus alba genotypes with contrasting phenotypes were selected from natural populations in Northern and Southern Italy. An experiment was carried out with plants individually grown in sand and submitted to a shock salinity stress. Ecophysiological measurements monitored the functionality of the leaf apparatus during the experiment and leaf samples were collected at 3h, 27h, and 75h after the starting of stress treatment to analyse gene expression and mineral uptake. Both photosynthetic assimilation and mithocondria respiration showed a significant reduction in salt treated plants compared to control. Leaf sodium content increased during the experiment, consistently with the duration of the stress treatment. Transcriptome regulation in leaves was analysed by cDNA microarrays. A RNA pooling design was applied to obtain a time course analysis of transcriptome regulation induced by salt stress. For both genotypes the number of differentially regulated genes increased from 3h to 75h. A detailed transcriptome analysis was then carried out on the individual plants collected at 75h. At this time point, most stress-regulated genes were down-regulated and common between the two genotypes. A small set of genes showed an expression profile significantly different between the two genotypes. Importantly, some of these genes showed an opposite behaviour between the genotypes compared (i.e. down- versus up-regulated). These genes are candidates for the intra-specific variability of salt stress response. The results of microarray analyses will be discussed in relation to the putative function of the stress-regulated genes and to the ecophysiological and mineral analyses.
Ecophysiological response and transcriptome regulation in mediterranean Populus alba genotypes submitted to shock salinity stress
Beritognolo I;Loreto F;Brilli F;
2006
Abstract
Salinity strongly limits soil fertility in the Mediterranean region. Thanks to its fast growth and biomass production, Populus alba L. is an interesting forest species for Mediterranean ecosystems and its native germplasm can provide genetic resources to improve tolerance to drought and salinity stress. The objective of this study was to investigate the mechanisms that underlie the variability of response to salinity stress within this species. Two Populus alba genotypes with contrasting phenotypes were selected from natural populations in Northern and Southern Italy. An experiment was carried out with plants individually grown in sand and submitted to a shock salinity stress. Ecophysiological measurements monitored the functionality of the leaf apparatus during the experiment and leaf samples were collected at 3h, 27h, and 75h after the starting of stress treatment to analyse gene expression and mineral uptake. Both photosynthetic assimilation and mithocondria respiration showed a significant reduction in salt treated plants compared to control. Leaf sodium content increased during the experiment, consistently with the duration of the stress treatment. Transcriptome regulation in leaves was analysed by cDNA microarrays. A RNA pooling design was applied to obtain a time course analysis of transcriptome regulation induced by salt stress. For both genotypes the number of differentially regulated genes increased from 3h to 75h. A detailed transcriptome analysis was then carried out on the individual plants collected at 75h. At this time point, most stress-regulated genes were down-regulated and common between the two genotypes. A small set of genes showed an expression profile significantly different between the two genotypes. Importantly, some of these genes showed an opposite behaviour between the genotypes compared (i.e. down- versus up-regulated). These genes are candidates for the intra-specific variability of salt stress response. The results of microarray analyses will be discussed in relation to the putative function of the stress-regulated genes and to the ecophysiological and mineral analyses.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
