Lipidomic Profiling of Argania spinosa L. (Skeels) Following Drought Stress.

Argan tree is frequently constrained by environmental stresses, especially drought. Lipids play crucial roles in stress adaptation, but lipidomic profiles in Argania spinosa under drought stress is largely unknown. The aim of this study was to identify lipid components potentially responsive to drought stress from leaves in the four argan ecotypes. For this, non-polar metabolite profiling was carried out using gas chromatography-mass spectrometry. We identified 228 components, the majority of which belonged to fatty acids and prenol lipids classes. The principal component analysis and partial least-squares discriminant analysis were applied to the lipidomics data to determine the component changes between all ecotypes. Based on the common components present in all ecotypes under contrast conditions, 21 metabolites belong fatty acids were identified with significant change. It was concluded that the majority of these components show up-accumulation in their content and involve in different pathways, especially in alpha-linolenic acid metabolism. The findings of this study provided new insights into the lipidomic study of argan leaves under drought stress and may be eventually contribute to overcoming drought; in addition, this could serve as a base for future studies on transcriptomic and proteomic to enhance the drought tolerance of forest trees.

Evaluation of microalgae polysaccharides as biostimulants of tomato plant defense using metabolomics and biochemical approaches.

Microalgal polysaccharides (PSs) may be an effective elicitor agent that can efficiently protect plants against biotic stresses. In this study, wee investigates, the effect of PS obtained from microalgae and cyanobacteria (D. salina MS002, P. tricorontum MS023, Porphyridium sp. MS081, Desmodesmus sp., D. salina MS067 and A. platensis MS001) on the biochemical and metabolomics markers linked to defense pathways in tomato plants. The phenylalanine ammonia lyase (PAL), chitinase, 1,3-beta-glucanase and peroxidase (POX) activities have been improved in tomato plants leaves treated by polysaccharides extracted from P. triocnutum (238.26%); Desmodesmus sp. (19.95%); P. triocnutum (137.50%) and Porphyridium sp. (47.28%) respectively. For proteins, polyphenols and H2O2, the maximum effect was induced by D. salina 067 (55.01%), Porphyridium sp. (3.97%) and A. platensis (35.08%) respectively. On the other hand, Gas Chromatography-mass spectrometry (GC-MS) metabolomics analysis showed that PSs induced the modification of metabolite profile involved in the wax construction of tomato leaves, such as fatty acids, alkanes, alkenes and phytosterol. PS treatments improved the accumulation of fatty acids C16:3, C18:2 and C18:3 released from the membrane lipids as precursors of oxylipin biosynthesis which are signaling molecules of plant defense. In addition, PS treatment induced the accumulation of C18:0 and Azelaic acid which is a regulator of salicylic acid-dependent systemic acquired resistance. However, molecular and metabolic studies can determine more precisely the mode of action of microalgal polysaccharides as biostimulants/elicitors plant defense.

Using two retrotransposon-based marker systems (SRAP and REMAP) for genetic diversity analysis of Moroccan Argan tree.

The Argania is an endemic genetic resource in Morocco holding an important ecological and socio-economical benefit. However, overgrazing and overharvesting lead to a serious downturn in the number of trees. To characterize genetic diversity within and among 24 populations, represented by 240 argan trees, four combinations of SRAP primers and eight combinations of REMAP primers were used. A total of 338 REMAP and 146 SRAP markers were amplified with a polymorphism of 100%. The average polymorphism information content value was 0.20 and 0.17 for SRAP and REMAP markers, respectively. The analysis of molecular variance showed that 26% of the genetic variation was partitioned among populations. The coefficient of gene differentiation was 0.2875 and gene flow was 1.2391. The average parameter diversity was: observed number of alleles (Na)=0.729, effective number of alleles (Ne)=1.131, Shannon's information index (I)=1.143; Nei's gene diversity (H)=0.093 and Percentage of Polymorphic Loci=35.68. The STRUCTURE and principal coordinate analysis revealed that the Argania spinosa L. populations were aggregated into 2 genetic groups. To detect outlier, baysecan software was used and 21 were detected (7 under selection, 14 under balancing selection) presenting posterior probability higher than 0.79. The current results can be explored in the design of management programs and to comprehend the adaptation mechanism of Argan tree.

Microalgae polysaccharides bio-stimulating effect on tomato plants: Growth and metabolic distribution.

Microalgae polysaccharides represent a potentially bioressource for the enhancement and the protection of agricultural crops. We investigate the possibility to use microalgae polysaccharides as a plant biostimulant. The crude polysaccharides extract (PS) from three microalgae strains were applied to Solanum lycopersicum plants by irrigation and compared basing on their effects on shoot and root length, nodes number and shoot and root dry weight. The application of 1 mg mL-1 PS from A. platensis, D. salina and Porphorydium sp. on tomato plants improved significantly the nodes number (NN), shoot dry weight (SDW), and shoot length (SS) by75 %, 46,6 %, 25,26 % compared to control respectively. Furthermore, crude PS treatment showed an improvement of carotenoid, chlorophyll and proteins content, and Nitrate Reductase (NR), NAD-Glutamate Dehydrogenase (NAD-GDH) activities in plants leaves compared to control. 1 mg mL-1 of Porphorydium sp. enhanced significantly the carotenoid content and NAD-GDH activity by 400 %, 200 % compared to control respectively. In the same way, A. platensis PS improved chl a, chl b and NR activity by 90.1 %, 102.7 % and 88.34 compared to control respectively. In addition, it is found that a PS treatment has affected the protein content, which reaches 88.3 % under 0.5 mg mL-1 of D. salina PS treatment. GC-MS metabolomics analysis also showed a change in lipids, sterol and alkanes profiles. Some sterols precursors were increased such as Cholesta-6,22,24-triene, which may indicate an enhancement of the biosynthesis of sterols and/or steroidal glycoalkaloids in treated plants. Therefore, this is an evidence to use microalgae polysaccharides as a plant biostimulant.