Abstract
BackgroundDurum wheat often faces water scarcity and high temperatures, two events that usually occur simultaneously in the fields. Here we report on the stress responsive strategy of two durum wheat cultivars, characterized by different water use efficiency, subjected to drought, heat and a combination of both stresses.ResultsThe cv Ofanto (lower water use efficiency) activated a large set of well-known drought-related genes after drought treatment, while Cappelli (higher water use efficiency) showed the constitutive expression of several genes induced by drought in Ofanto and a modulation of a limited number of genes in response to stress. At molecular level the two cvs differed for the activation of molecular messengers, genes involved in the regulation of chromatin condensation, nuclear speckles and stomatal closure. Noteworthy, the heat response in Cappelli involved also the up-regulation of genes belonging to fatty acid β-oxidation pathway, glyoxylate cycle and senescence, suggesting an early activation of senescence in this cv. A gene of unknown function having the greatest expression difference between the two cultivars was selected and used for expression QTL analysis, the corresponding QTL was mapped on chromosome 6B.ConclusionOfanto and Cappelli are characterized by two opposite stress-responsive strategies. In Ofanto the combination of drought and heat stress led to an increased number of modulated genes, exceeding the simple cumulative effects of the two single stresses, whereas in Cappelli the same treatment triggered a number of differentially expressed genes lower than those altered in response to heat stress alone. This work provides clear evidences that the genetic system based on Cappelli and Ofanto represents an ideal tool for the genetic dissection of the molecular response to drought and other abiotic stresses.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-14-821) contains supplementary material, which is available to authorized users.
Highlights
Durum wheat often faces water scarcity and high temperatures, two events that usually occur simultaneously in the fields
drought stress (DS) was imposed by withholding water and allowing the pots to reach a Soil Water Content (SWC) equal to 12.5%, while heat stress (HS) was imposed progressively exposing the plants for two days at 30°C followed by additional two days at 34°C, and subsequently to 40°C
Cappelli showed a lower RWC compared to Ofanto, a condition that could be explained by a different capacity of water uptake from soil
Summary
Durum wheat often faces water scarcity and high temperatures, two events that usually occur simultaneously in the fields. The molecular response of plants to abiotic stress is mediated by a number of molecules involved in signal transduction leading to the activation of specific gene networks resulting from the re-programming of cell expression machinery. To these networks belong genes coding for a variety of proteins involved in DNA remodeling, transcription regulation, protein modifications, etc. A number of publications described the transcriptional changes induced in response to drought [7,8,9] and heat [10,11] stresses, much less is known when plants are simultaneously subjected to drought and heat stress, an event very common under field conditions. Most of the publications cited above have been carried out on seedlings and might not reflect exactly the molecular response of crops exposed to stress when plants are in more advanced growing stages
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