Drought resiliency strategies combine developmental, physiological, cellular, and molecular mechanisms. Here, we compare drought responses in two resilient spring wheat (Triticum aestivum) genotypes: a well-studied drought-resilient Drysdale and a resilient genotype from the US Pacific North-West Hollis. While both genotypes utilize higher water use efficiency through the reduction of stomatal conductance, other mechanisms differ. First, Hollis deploys the drought escape mechanism to a greater extent than Drysdale by accelerating the flowering time and reducing root growth. Second, Drysdale uses physiological mechanisms such as non-photochemical quenching (NPQ) to dissipate the excess of harvested light energy and sustain higher Fv/Fm and ϕPSII, whereas Hollis maintains constant NPQ but lower Fv/Fm and ϕPSII values. Furthermore, more electron donors of the electron transport chain are in the oxidized state in Hollis than in Drysdale. Third, many ROS homeostasis parameters, including peroxisome abundance, transcription of peroxisome biogenesis genes PEX11 and CAT, catalase protein level, and enzymatic activity, are higher in Hollis than in Drysdale. Fourth, transcription of autophagy flux marker ATG8.4 is upregulated to a greater degree in Hollis than in Drysdale under drought, whereas relative ATG8 protein abundance under drought stress is lower in Hollis than in Drysdale. These data demonstrate the activation of autophagy in both genotypes and a greater autophagic flux in Hollis. In conclusion, wheat varieties utilize different drought tolerance mechanisms. Combining these mechanisms within one genotype offers a promising strategy to advance crop resiliency.
Triticum monococcum subsp. monococcum as a first cultivated diploid wheat species possesses desirable agronomic and quality characteristics. Drought and salinity are the most dramatic environmental stress factors that have serious impact on yield and quality of crops; however, plants can use alternative defense mechanisms against these stresses. The posttranscriptional alteration of gene expression by microRNAs (miRNAs) is one of the most conserved mechanisms. In plant species including wheat genomes, miRNAs have been implicated in the management of salt and drought stress; however, studies on einkorn wheat (Triticum monococcum subsp. monococcum) are not yet available. In this study, we aimed to identify conserved miRNAs in einkorn wheat using next generation sequencing technology and bioinformatics analysis. In order to include a larger set of miRNAs, small RNA molecules from pooled plant samples grown under normal, drought, and salinity conditions were used for the library preparation and sequence analysis. After bioinformatics analysis, we identified 167 putative mature miRNA sequences belonging to 140 distinct miRNA families. We also presented a comparative analysis to propose that miRNAs and their target genes were involved in salt and drought stress control in addition to a comprehensive analysis of the scanned target genes in the T. aestivum genome.
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