Project description:Background: Drought stress is the major environmental stress that affects plant growth and productivity. It triggers in plants a wide range of responses detectable at different scales: molecular, biochemical and physiological levels. At the molecular level the response to drought stress results in the differential expression of several metabolic pathways. For this reason, explore the subtle differences existing in gene expression of drought sensitive and drought tolerant genotypes allows to identify drought-related genes that could be used for selection of drought tolerance traits. Genome-wide RNA-Seq technology was used to compare the drought response of two sorghum genotypes characterized by contrasting water use efficiency. Results: the physiological measurements carried out confirmed the drought sensitivity of IS20351 and the drought tolerance of IS22330 previously studied. The expression of drought-related genes was more abundant in the sensitive genotype IS20351 compared to the tolerant IS22330. The Gene Ontology enrichment highlighted a massive increase in transcript abundance in “response to stress” and “abiotic stimulus”, “oxidation-reduction reaction” in the sensitive genotype IS20351 under drought stress. “Antioxidant” and “secondary metabolism”, “photosynthesis and carbon fixation process”, “lipids” and “carbon metabolism” were the pathways most affected by drought in the sensitive genotype IS20351. The sensitive genotype IS20351 showed under well-watered conditions a lower constitutive expression level of “secondary metabolic process” (GO:0019748) and “glutathione transferase activity” (GO:000004364). Conclusions: RNA-Seq analysis revealed to be a very useful tool to explore differences between sensitive and tolerant sorghum genotypes. The transcriptomic results supported all the physiological measurements and were crucial to clarify the tolerance of the two genotypes studied. The connection between the differential gene expression and the physiological response to drought states unequivocally the drought tolerance of the genotype IS22330 and the strategy adopted to cope with drought stress.

Project description:Grafting is a well-established practice for grapevine to facilitate propagation of productive and tolerant cultivars against several stress factors. It is also considered to be a suitable method for studying molecular aspects of root-to-shoot and/or shoot-to-root signaling events. So far, controlling only effect of rootstock over scion was investigated and root-to-shoot transcriptomic alterations were fallowed on the scions or graft interfaces. The objective of this study was to investigate transcriptomic and physiological influence of scion on the rootstock under drought stress. Therefore, drought tolerant 110R rootstock were firstly grafted with sultana seedless and tested under drought stress with its non-grafted counterpart. The results of treatment indicated that grafted 110R performed the highest root elongation under drought. We carried out a microarray based transcriptome analysis on the roots of grafted and non-grafted 110R to explain this drought derived interaction through scion-to-rootstock. The highest expression increase under drought was recorded for sugar (SWEET) and nitrate or di/tri-peptide (NRT1/ PTR FAMILY) transporter proteins. Expression level of these genes was more highly increased in grafted 110R than its non-grafted counterpart. This situation indicated their potential role in drought tolerance and scion/rootstock harmony. Overexpression of these transporters attributed to increased amount of released nutrient and nitrogen source from abscised leaves of sultana seedless under drought. Remobilization of these rich sources was suggested to chance transcriptomic response of rootstocks and enabled much better growth in grafted 110R. Other transcripts annotated to cell wall modification enzymes (chitinases), osmoregulator proteins (dehydrins, proline-glycine rich proteins) and secondary metabolites (stilbene synthase) were also more highly induced in grafted 110R. This is the first report indicating transcriptomic influence of scion on the grapevine rootstocks and representing the genes responsible in scion/rootstock harmony and drought tolerance.

Project description:Drought is one of the most important environmental fluctuations affecting tree growth and survival. Therefore, understanding of physiological and transcriptomic responses of trees to this stress factor will make important contributions to forest health and productivity. Here, we report comparative physiological and microarray based transcriptome analysis between drought resistant (N.62.191) and drought-sensitive (N.03.368.A) black poplar genotypes under well-watered (WWP), moderate drought (MD), severe drought (SD) and post drought re-watering (PDR) conditions. In the study, sensitive genotype exhibited a drought escape strategy with lower leaf water potential, higher reactive oxygen production, complete leaf abscission and subsequent terminal shoot necrosis under drought stress. On the other hand, resistant genotype had a dehydration tolerance indicating highly delayed leaf abscission under drought and fast growing capacity during re-watering conditions. Gene ontology enrichment analysis attributed drought susceptibility of black poplar to significant up-regulation of genes functional in transcription regulation (AP2/ERF, NAC and WRKY), cell wall modification (Expansins), fatty acid metabolism (enoyl-ACP reductase, lipid transport protein particle), protein degradation (endopeptidases), ethylene synthesis (1-aminocyclopropane-1-carboxylate) and riboflavin synthesis (GTP cyclohydrolase II) under drought stress. Transcriptomic comparison indicated significant down-regulation of photosynthesis, electron transport and carbohydrate metabolism related genes under drought stress in sensitive genotype. Although, similar reduction in carbohydrate metabolism was also recorded for resistant genotype, genes related with photosynthesis and electron transport systems were not down regulated even under SD for this genotype. Resistant genotype specific up-regulation of small heat shock proteins (sHSP) and bark storage proteins revealed importance of protein protection and nitrogen remobilization under drought stress, respectively. This is the first study associating BSP production to delayed leaf abscission and drought tolerance in trees.

Project description:Drought is an inevitable stress almost all terrestrial plants face in their life cycles. Desert dwelling plants show extreme adaptations to drought but their genomes are largely unexplored compared to drought sensitive model plants generally studied to understand plant drought tolerance. Haloxylon ammodendron is a pioneer species extremely tolerant to drought and capable of colonizing desert sand dunes. Seedling establishment is the most critical development stage in the survival of H. ammodendron. H. ammodendron seedlings are able to withstand high light, and low temperature stresses characteristic of temperate desert environments in addition to drought. We have investigated the genome-wide transcript responses under induced drought stress during early seedling establishment to identify prevailing basal and induced gene clusters that likely contribute to survival and stress adapted growth in H. ammodendron. We find staggering support for drought response transcript accumulation together with other transcripts that may transform the cellular expression space into a preadapted state for salt, light, osmotic, and temperature stress tolerance. While transcript accumulation is excessive for genes associated with abiotic stress tolerance under an induced drought treatment, H. ammodendron seems to enhance biotic stress tolerance simultaneously by down-regulation of several genes that would be found at an up-regulated state during pathogen entry in susceptible plants. We detected enriched basal level transcript allocation that suggests preadaptation to abiotic stresses as well as pathogen defense in H. ammodendron when compared to other Amaranthaceae family transcriptomes under stress neutral conditions. Amaranthaceae is one of the most enriched plant families for extremophytes. We found transcripts that are generally maintained at low levels and some induced only under abiotic stress in Arabidopsis thaliana to be highly expressed under basal conditions in the Amaranthaceae transcriptomes including H. ammodendron. These could be novel candidates to expand or initiate discovery of new stress adaptive gene networks and mechanisms naturally selected in extremophytes that allow survival under environmental stresses.

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Quantitative proteomic analysis of the role of miRNA156 in alfalfa under drought stress

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