Isolation of bacterial strains from compost teas and screening of their PGPR properties on potato plants

The beneficial effect of compost and compost tea on plant growth and protection is mainly associated with the microbial diversity and the presence of bacteria with plant growth–promoting effect. PGPR are considered as eco-friendly bio-fertilizers that may reduce the use of chemical pesticides and fertilizers. Three composts (AT, A10, and A30) were previously prepared from industrial wastes (olive mill wastewater, olive pomace, coffee ground, and phosphogypsum). In the present study, we isolated three bacterial strains from the compost teas. The phylogenetic identification of these bacterial strains (B.AT, B.A10, and B.A30) showed that they correspond to Serratia liquefaciens (B.AT and B.A10) and Achromobacter spanius (B.A30) species. A further characterization of the PGPR traits of these bacteria showed that they produce siderophore, exopolysaccharides, and IAA. Their effect on potato plant growth, yields, and tuber quality was performed under field culture conditions. Results showed that these strains can be characterized as PGPR, the best effect on potato plant growth was observed with Serratia liquefaciens (B.AT), the best yield and tuber quality was observed with Serratia liquefaciens (B.A10) while bacterial treatment with Achromobacter spanius (B.A30) is a Cd-tolerant PGPR.This work was financially supported by the Tunisian Ministry of High Education and Scientific Research

Improved growth and tuber quality of transgenic potato plants overexpressing either NHX antiporter, CLC chloride channel, or both

International audienceThe nutritional enhancement of potato plants (Solanum tuberosum L.,) is highly critical. As it is considered a worldwide basic vegetarian nutrition to maintain health. S. tuberosum is one of the foremost staples and the world's fourth-largest food crop. In advance, its need is increasing because of its high-industrial value and population blast. To improve both potato growth and behavior under harsh environmental conditions, we produced transgenic potato plants overexpressing either VvNHX (a sodium proton antiporter from Vitis vinifera), VvCLC (a chloride channel from Vitis vinifera), or both. Control and transgenic plants were grown in greenhouse and field under non-stressed conditions for 85 days in order to characterize their phenotype and evaluate their agronomical performance. To this aim, the evaluation of plant growth parameters, tuber yields and characteristics (calibers, eye number and color), the chemical composition of tubers, was conducted and compared between the different lines. The obtained results showed that transgenic plants displayed an improved growth (flowering precocity, gain of vigor and better vegetative growth) along with enhanced tuber yields and quality (increased protein and starch contents). Our findings provide then insight into the role played by the VvNHX antiport and the VvCLC channel and a greater understanding of the effect of their overexpression in potato plants

Plants take action to mitigate salt stress: Ask microbe for help, phytohormones, and genetic approaches

Global agriculture is a pivotal activity performed by various communities worldwide to produce essential human food needs. Plant productivity is limited by several factors, such as salinity, water scarcity, and heat stress. Salinity significantly causes short or long-term impacts on the plant photosynthesis mechanisms by reducing the photosynthetic rate of CO2 assimilation and limiting the stomatal conductance. Moreover, disturbing the plant water status imbalance causes plant growth inhibition. Up-regulation of several plant phytohormones occurs in response to increasing soil salt concentration. In addition, there are different physiological and biochemical mechanisms of salt tolerance, including ion transport, uptake, homeostasis, synthesis of antioxidant enzymes, and osmoprotectants. Besides that, microorganisms proved their ability to increase plant tolerance, Bacillus spp. represents the dominant bacteria of the rhizosphere zone, characterised as harmless microbes with extraordinary abilities to synthesise many chemical compounds to support plants in confronting salinity stress. In addition, applying arbuscular mycorrhizal fungi (AMF) is a promising method to decrease salinity-induced plant damage as it could enhance the growth rate relative to water content. In addition, there is a demand to search for new salt-tolerant crops with more yield and adaptation to unfavourable environmental conditions. The negative impact of salinity on plant growth and productivity, photosynthesis, stomatal conductance, and changes in plant phytohormones biosynthesis, including abscisic acid and salicylic acid, jasmonic acid, ethylene, cytokinins, gibberellins, and brassinosteroids was discussed in this review. The mechanisms evolved to adapt and/or survive the plants, including ion homeostasis, antioxidants, and osmoprotectants biosynthesis, and the microbial mitigate salt stress. In addition, there are modern approaches to apply innovative methods to modify plants to tolerate salinity, especially in the essential crops producing probable yield with a notable result for further optimisation and investigations