Transcriptome assembly and abiotic related gene expression analysis of date palm reveal candidate genes involved in response to cadmium stress.

Date palm in Tunisia is of major economic importance but are also factors of social, environmental and economic stability. An annotated assembly of the transcriptome of cultivar Deglet Nour was reported. RNA was isolated from plant Cd-contaminated leaves, and 37,049 unique Illumina RNA-seq reads were used in a transcriptome assembly. The draft transcriptome assembly consists of 6789 contigs and 17.285 singletons with a means length of 858 bp and 1.042 bp, respectively. The final assembly was functionally annotated using Blast2GO software, allowing the identification of putative genes controlling important agronomic traits. The annotated transcriptome data sets were used to query all known Kyoto Encyclopedia of Genes and Genomes pathways. The most represented molecular functions and biological processes were nucleotide binding and transcription, transport and response to stress and abiotic and biotic stimuli. A prediction of the genes interaction network was proposed by selecting corresponding functionally similar genes from Arabidopsis datasets, downloaded by GeneMANIA version 2.1. Several Cd-responsive genes expression was monitored in in vitro isolated explant of Cd stressed Deglet Nour. Some chelators encoding genes were upregulated confirming in silico findings. Genes encoding HMs transporters in date palm showed expression enhancement more pronounced after 20 days of exposure. P. dactylifera transcriptome provides a valuable resource for future functional analysis of candidate genes involved in metal stress response.

RK, the first scorpion peptide with dual disintegrin activity on α1ß1 and αvß3 integrins.

Scorpion peptides are well known for their pharmaceutical potential on different targets. These include mainly the ion channels which were found to be highly expressed in many diseases, including cancer, auto-immune pathologies and Alzheimer. So far, however, the disintegrin activity had only been characterized for snake venom molecules. Herein, we present the first short peptide, purified from the venom of Buthus occitanus tunetanus, (termed RK) able to inhibit the cell adhesion of Glioblastoma, Melanoma and Rat pheochromocytoma to different extracellular matrix (ECM) receptors. Anti-integrin antibody assay suggests that RK interacts with both α1ß1 and αvß3 with a more pronounced effect for the former. The examination of the primary structure of RK suggests the involvement of two motifs: KSS, analogue to KTS which was characterized for α1ß1 Snake venom disintegrins, and ECD, analogue to RGD which was found to be active on αvß3. To assess their roles in the disintegrin activity of RK, we conducted a computational analysis. The molecular docking study shows that RK involves mainly two segments to interact with the α1ß1 integrin, but the peptide does not implicate the KSS motif in the interaction. The molecular modeling study, suggests the key contribution of the ECD segment in the interaction with αvß3 integrin.

The phytochelatin synthase gene in date palm (Phoenix dactylifera L.): Phylogeny, evolution and expression.

We studied date palm phytochelatin synthase type I (PdPCS1), which catalyzes the cytosolic synthesis of phytochelatins (PCs), a heavy metal binding protein, in plant cells. The gene encoding PdPCS1 (Pdpcs) consists of 8 exons and 7 introns and encodes a protein of 528 amino acids. PCs gene history was studied using Notung phylogeny. During evolution, gene loss from several lineages was predicted including Proteobacteria, Bilateria and Brassicaceae. In addition, eleven gene duplication events appeared toward interior nodes of the reconciled tree and four gene duplication events appeared toward the external nodes. These latter sequences belong to species with a second copy of PCs suggesting that this gene evolved through subfunctionalization. Pdpcs1 gene expression was measured in seedling hypocotyls exposed to Cd, Cu and Cr using quantitative real-time polymerase chain reaction (qPCR). A Pdpcs1 overexpression was evidenced in P. dactylifera seedlings exposed to metals suggesting that 1-the Pdpcs1 gene is functional, 2-there is an implication of the enzyme in metal detoxification mechanisms. Additionally, the structure of PdPCS1 was predicted using its homologue from Nostoc (cyanobacterium, NsPCS) as a template in Discovery studio and PyMol software. These analyses allowed us to identify the phytochelatin synthase type I enzyme in date palm (PdPCS1) via recognition of key consensus amino acids involved in the catalytic mechanism, and to propose a hypothetical binding and catalytic site for an additional substrate binding cavity.

Morphological, Physiological and Biochemical Impact of Ink Industry Effluent on Germination of Maize (Zea mays), Barley (Hordeum vulgare) and Sorghum (Sorghum bicolor).

The present study focuses on effects of untreated and treated ink industry wastewater on germination of maize, barley and sorghum. Wastewater had a high chemical oxygen demand (COD) and metal content compared to treated effluent. Germination decreased with increasing COD concentration. Speed of germination also followed the same trend, except for maize seeds exposed to untreated effluent (E), which germinated slightly faster than controls. These alterations of seedling development were mirrored by changes in soluble protein content. E exerted a positive effect on soluble protein content and maximum levels occurred after 10 days with treated effluent using coagulation/flocculation (TEc/f) process and treated effluent using combined process (coagulation/flocculation/biosorption) (TEc/f/b). Likewise, activity of α-amylase was influenced by effluent composition. Its expression depended on the species, exposure time and applied treatment. Nevertheless, current results indicated TEc/f/b had no observable toxic effects on germination and could be a beneficial alternative resource to irrigation water.

Physiological responses of fenugreek seedlings and plants treated with cadmium.

The bioaccumulation efficiency of cadmium (Cd) by fenugreek (Trigonella foenum-graecum) was examined using different concentrations of CdCl2. The germination rate was similar to control except at 10 mM Cd. However, early seedling growth was quite sensitive to the metal from the lowest Cd level. Accordingly, amylase activity was reduced substantially on treatment of seeds with 0.5, 1, and 10 mM Cd. Cadmium also affected various other plant growth parameters. Its accumulation was markedly lower in shoots as compared to roots, reducing root biomass by almost 50 %. Plants treated with 1 and 5 mM Cd presented chlorosis due to a significant reduction in chlorophyll b especially. Furthermore, at Cd concentrations greater than 0.1 mM, plants showed several signs of oxidative stress; an enhancement in root hydrogen peroxide (H2O2) level and in shoot malondialdehyde (MDA) content was observed. Conversely, antioxidant enzyme activities (superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT)) increased in various plant parts. Likewise, total phenolic and flavonoid contents reached their highest values in the 0.5 mM Cd treatment, consistent with their roles in quenching low concentrations of reactive oxygen species (ROS). Consequently, maintaining oxidant and antioxidant balance may permit fenugreek to hyperaccumulate Cd and allow it to be employed in extremely Cd polluted soils for detoxification purposes.