Search

Additional file 6: Figure S5. Three-dimension PCA for RNAseq correlation. Principal Component coordinates were calculated using sample read counts. Figure S6 - Hierarchical clustering map for differential expression genes.

Additional file 3: Figure S3. Flowchart of sequencing and de novo assembly of A.donax leaf and root transcriptome under cadmium treatment.

Additional file 4: Figure S4. Length distribution of transcripts and unigenes.

Additional file 2: Figure S2. Effect of cadmium treatment on morpho-biometric and physiological parameters of A. donax G10 ecotype. A) Main stem height per pot. B) Biomass dry weight. C) Net photosynthesis efficiency.

To compensate for the lack of information about the molecular mechanism involved in Arundo donax L. response to salt stress, we de novo sequenced, assembled and analyzed the A. donax leaf transcriptome subjected to two levels of long-term salt stress (namely, S3 severe and S4 extreme).The picture that emerges from the identification of differentially expressed genes is consistent with a salt dose-dependent response. Hence, a deeper re programming of the gene expression occurs in those plants grew at extreme salt level than in those subjected to severe salt stress, probably representing for them an “emergency” state. In particular, we analyzed clusters related to salt sensory and signaling, transcription factors, hormone regulation, Reactive Oxygen Species (ROS) scavenging, osmolyte biosynthesis and biomass production, all of them showing different regulation either versus untreated plants or between the two treatments. Importantly, the photosynthesis is strongly impaired in samples treated with both levels of salinity stress. However, in extreme salt conditions, a dramatic switch from C3 Calvin cycle to C4 photosynthesis is likely to occur, this probably being the more impressive finding of our work. Considered the distinct response to salt doses, genes either involved in severe or in extreme salt response could constitute useful markers of the physiological status of A. donax to deepen ourunderstanding of its biology and productivity in salinized soil. Finally, many of the unigenes identified in the present study have the potential to be used for the development of A. donax varieties with improved productivity and stress tolerance, in particular the knock out of the GTL1 gene acting as negative regulator of water use efficiency has been proposed as good target for genome editing.