Plant NHX Antiporters: From Function to Biotechnological Application, with Case Study.

Salt stress is one of the major abiotic stresses that negatively affect crops worldwide. Plants have evolved a series of mechanisms to cope with the limitations imposed by salinity. Molecular mechanisms, including the upregulation of cation transporters such as the Na+/H+ antiporters, are one of the processes adopted by plants to survive in saline environments. NHX antiporters are involved in salt tolerance, development, cell expansion, growth performance and disease resistance of plants. They are integral membrane proteins belonging to the widely distributed CPA1 sub-group of monovalent cation/H+ antiporters and provide an important strategy for ionic homeostasis in plants under saline conditions. These antiporters are known to regulate the exchange of sodium and hydrogen ions across the membrane and are ubiquitous to all eukaryotic organisms. With the genomic approach, previous studies reported that a large number of proteins encoding Na+/H+ antiporter genes have been identified in many plant species and successfully introduced into desired species to create transgenic crops with enhanced tolerance to multiple stresses. In this review, we focus on plant antiporters and all the aspects from their structure, classification, function to their in silico analysis. On the other hand, we performed a genome-wide search to identify the predicted NHX genes in Argania spinosa L. We highlighted for the first time the presence of four putative NHX (AsNHX1-4) from the Argan tree genome, whose phylogenetic analysis revealed their classification in one distinct vacuolar cluster. The essential information of the four putative NHXs, such as gene structure, subcellular localization and transmembrane domains was analyzed.

Screening of microalgae liquid extracts for their bio stimulant properties on plant growth, nutrient uptake and metabolite profile of Solanum lycopersicum L.

The present study investigates the biostimulant effects of 18 Crude Bio-Extracts (CBEs) obtained from Microalgae and Cyanobacteria on tomato plant growth, chlorophyll content, nutrient uptake and metabolite profile. Significant root and shoot length improvement (112.65%, 53.70%); was recorded at treatment with Aphanothece sp and C. ellipsoidea CBEs respectively. Meanwhile, the highest root and shoot dry weight (DW) (34.81%, 58.69%) were obtained at treatment with Aphanothece sp. The latter also displayed the maximum uptake of Nitrogen, phosphorus and potassium, which increased by 185.17%, 119.36% and 78.04% respectively compared with non-treated plants. Principal Component Analysis (PCA) confirmed that Phosphorus and Potassium levels in roots were closely related to enhanced Root length, whereas Nitrogen and chlorophyll b were closely related to Shoot and root DW. Additionally, Gas Chromatography-mass spectrometry (GC-MS) indicated that treatment with CBEs, induced the production of a vast array of metabolites. Treated plants recorded higher accumulation of palmitic and stearic acids, which could indicate a stimulation in de novo Lipid synthesis. CBEs also triggered the accumulation of pyridine-3-carboxamide (an amide active form of vitamin B3) and Linolenic acid; one of the key precursors in the biosynthetic pathway leading to plant jasmonates. Our results are a first step towards understanding the effects of microalgal extracts on plant physiology and biochemical pathways. Further investigations on biochemical fractionation of microalgal extracts and agronomic tests of their purified bioactive compounds could be a useful principal novelty for in-depth study of CBE action mechanisms. Other useful tools include; Comparative hormone profiling of treated and non-treated plants accompanied with combined High-Throughput Plant Phenotyping, transcriptomics and metabolomics analysis.

Effect of Microalgae Polysaccharides on Biochemical and Metabolomics Pathways Related to Plant Defense in Solanum lycopersicum.

Microalgae are photosynthetic microorganisms that produce several bioactive molecules that have received considerable attention in scientific and industrial communities. Today, many plant biostimulants including seaweed extracts and polysaccharides are used in agriculture. However, microalgae have not been largely exploited in this field as a potential source of plant bio stimulants. This study investigated the biostimulatory effects of microalgae polysaccharides on different metabolomic and biochemical pathways related to plant defense. 0.2 mg mL-1 of crude polysaccharides extracted from four green microalgae strains was injected into tomato plants (Solanum lycopersicum). ß-1,3-glucanase activity, lipid remodeling, phenylalanine ammonia lyase (PAL), Lipoxygenase (LOX), and antioxidant enzyme (APX, POD and CAT) activities were evaluated 48 h after treatment. Plants treated with crude polysaccharides extracted from. C. vulgaris and C. sorokiniana exhibited a significant increase in ß-1,3-glucanase activity. Accordingly, C. sorokiniana crude polysaccharides had a significant stimulatory effect on PAL activity with a percentage increase of 188.73% compared to the control. GC/MS quantitative lipidomics analysis revealed that treatment with D. salina, C. sorokiniana, and C. reinhardtii crude polysaccharides increased PUFA content by 50.37%, 34.46%, and 33.37% respectively. Microalgae polysaccharides also enhanced stearic acid, palmitic acid, and VLCFA content, the optimal value of which increased by 45.50%, 32.83%, and 60.60% respectively under treatment with C. reinhardtii crude polysaccharides compared with the control. C. vulgaris and C. reinhardtii crude polysaccharides also exhibited higher APX and POD activity respectively. The present results therefore indicate the potentiality of microalgae crude polysaccharides as a promising renewable bio resource in the development plant bio stimulants.