Salinization of soil with sodium chloride ions inhibits plant functions, causing reduction of yield of crops. Salt tolerant microorganisms have been studied to enhance crop growth under salinity. This review describes the performance of endophytic fungi applied to crops as a supplement to plant genetics or soil management to alleviate salt stress in crops. This is achieved via inducing systemic resistance, increasing the levels of beneficial metabolites, activating antioxidant systems to scavenge ROS, and modulating plant growth phytohormones. Colonization by endophytic fungi improves nutrient uptake and maintains ionic homeostasis by modulating ion accumulation, thereby restricting the transport of Na+ to leaves and ensuring a low cytosolic Na+:K+ ratio in plants. Participating endophytic fungi enhance transcripts of genes encoding the high Affinity Potassium Transporter 1 (HKT1) and the inward-rectifying K+ channels KAT1 and KAT2, which play key roles in regulating Na+ and K+ homeostasis. Endophytic-induced interplay of strigolactones play regulatory roles in salt tolerance by interacting with phytohormones. Future research requires further attention on the biochemical, molecular and genetic mechanisms crucial for salt stress resistance requires further attention for future research. Furthermore, to design strategies for sustained plant health with endophytic fungi, a new wave of exploration of plant-endophyte responses to combinations of stresses is mandatory.

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Alleviation of salinity stress in plants by endophytic plant-fungal symbiosis: Current knowledge, perspectives and future directions

Continuous cropping of soybean causes soil degradation and soybean yield decline, but these effects could be alleviated by crop rotation or the use of long-term continuously cropped soybean systems. However, the mechanism by which biotic and abiotic factors are affected by different cropping systems remain unclear. In this study, we comparatively investigated the bacterial and fungal abundance, diversity and community compositions in the bulk and rhizospheric soils of soybean continuously cropped in the short-term for 3 and 5 years (CC3 and CC5) and in the long-term for 13 years (CC13), as well as cropping rotation with maize in alternately for 5 years (CR5) using qPCR and high-throughput sequencing methods. The results showed that soil pH, and available nutrients such as N, P and K were significantly higher in the bulk soils of CC13 and CR in contrast to CC3 and CC5. The fungi/bacteria ratio was significantly higher in the rhizospheric soils of CC3 and CC5 than that in CR5 and CC13, indicating that short-term continuously cropped soybean decreases bacterial abundance but increases fungal abundance. The bacterial and fungal community structures were significantly altered by different cropping systems, and the soil pH and C/N were the primary soil factors in shifting the bacterial and fungal community structures in the bulk soils, respectively. Bacterial and fungal co-occurrence patterns were remarkably affected by cropping systems, which showed that CC13 and CR5 harbor co-occurrence networks that are more complex than CC3 and CC5. Moreover, CC13 and CR5 increased the relative abundances of potentially beneficial bacteria Bradyrhizobium sp. and Gemmatimonas sp. and fungi Mortierella sp. and Paecilomyces sp. but decreased the relative abundances of the pathogenic fungi Fusarium sp. in contrast to CC3 and CC5, which indicated that long-term continuous cropping of soybean might have generated a possibility of the development of disease-suppressive soils.

Long-term continuous cropping of soybean is comparable to crop rotation in mediating microbial abundance, diversity and community composition

The world faces two enormous challenges that can be met, at least in part and at low cost, by making certain changes in agricultural practices. There is need to produce enough food and fibre for a growing population in the face of adverse climatic trends, and to remove greenhouse gases to avert the worst consequences of global climate change. Improving photosynthetic efficiency of crop plants can help meet both challenges. Fortuitously, when crop plants' roots are colonized by certain root endophytic fungi in the genus Trichoderma, this induces up-regulation of genes and pigments that improve the plants' photosynthesis. Plants under physiological or environmental stress suffer losses in their photosynthetic capability through damage to photosystems and other cellular processes caused by reactive oxygen species (ROS). But certain Trichoderma strains activate biochemical pathways that reduce ROS to less harmful molecules. This and other mechanisms described here make plants more resistant to biotic and abiotic stresses. The net effect of these fungi's residence in plants is to induce greater shoot and root growth, increasing crop yields, which will raise future food production. Furthermore, if photosynthesis rates are increased, more CO2 will be extracted from the atmosphere, and enhanced plant root growth means that more sequestered C will be transferred to roots and stored in the soil. Reductions in global greenhouse gas levels can be accelerated by giving incentives for climate-friendly carbon farming and carbon cap-and-trade programmes that reward practices transferring carbon from the atmosphere into the soil, also enhancing soil fertility and agricultural production.

Endophytic strains of Trichoderma increase plants’ photosynthetic capability

Both drought and salinity represent the greatest plant abiotic stresses in crops. Increasing plant tolerance against these environmental conditions must be a key strategy in the development of future agriculture. The genus of Trichoderma filament fungi includes several species widely used as biocontrol agents for plant diseases but also some with the ability to increase plant tolerance against abiotic stresses. In this sense, using the species T. parareesei and T. harzianum, we have verified the differences between the two after their application in rapeseed (Brassica napus) root inoculation, with T. parareesei being a more efficient alternative to increase rapeseed productivity under drought or salinity conditions. In addition, we have determined the role that T. parareesei chorismate mutase plays in its ability to promote tolerance to salinity and drought in plants by increasing the expression of genes related to the hormonal pathways of abscisic acid (ABA) under drought stress, and ethylene (ET) under salt stress.

Trichoderma parareesei Favors the Tolerance of Rapeseed (Brassica napus L.) to Salinity and Drought Due to a Chorismate Mutase

Unravelling the biochemistry and genetics of ACC deaminase-An enzyme alleviating the biotic and abiotic stress in plants

Trichoderma harzianum mitigates salt stress in cucumber via multiple responses.

Large-Scale Synthesis of High Loading Co Single-Atom Catalyst with Efficient Oxidase-Like Activity for the Colorimetric Detection of Acid Phosphatase

Ultrafast synthesized monometallic nanohybrids as an efficient quencher and recognition antenna of upconversion nanoparticles for the detection of xanthine with enhanced sensitivity and selectivity.

Fengshou Tian

Papers

Trichoderma harzianum mitigates salt stress in cucumber via multiple responses.

Large-Scale Synthesis of High Loading Co Single-Atom Catalyst with Efficient Oxidase-Like Activity for the Colorimetric Detection of Acid Phosphatase

Ultrafast synthesized monometallic nanohybrids as an efficient quencher and recognition antenna of upconversion nanoparticles for the detection of xanthine with enhanced sensitivity and selectivity.

Two-dimensional lateral anatase-rutile TiO2 phase junctions with oxygen vacancies for robust photoelectrochemical water splitting.