## Introduction  
The salinization of cultivable soils is a major issue that humankind will soon have to face. It has been estimated that around 20% of the world's land is cultivable, and over 30%, at present, is affected by salinization [1]. Moreover, it has been calculated by economists and agronomists that each year, about 10% of arable soils increase their own salt content, due, for instance, to irrigation with salted water and the use of incorrect agricultural practices, such as abundant use of mineral fertilizers [2]. Consequently, it is conceivable that in the next thirty years, more than 50% of them will be severely affected by a high salt content, causing a reduction in crop yields and also their palatability. It has been recognized that a relevant role to maintain and improve plant health is played by rhizosphere microorganisms colonizing the fine plant roots. The new-generation sequence (NGS) technique, able to sequence up to the whole genome of every kind of living being, has revealed an unknown world of microorganisms that inhabit the rhizosphere, and many of them carry out the function of plant growth promoters (PGP microorganisms), reducing either biotic or abiotic stresses, such as that caused, for instance, by soil salinization [3]. The tolerance to high salt concentrations of certain microorganism strains and their capability to improve the plant wellness have been demonstrated by several studies, also reported in this Special Issue, which, in fact, has collected papers focused on the interactions among plants and microorganisms when they are exposed to salty and/or arid soil. In this framework, seven papers have been published meeting the interest of the readers. In particular, [PERSON] et al. [4] focused their attention on the selection of novel halo/thermo-tolerant bacteria from the rhizosphere of glycopytes and haplotypes, grown in compost-amended soil and watered with 150/300 mM NaCl. Beneficial effects on the biomass, well-being and resilience, exerted on the assayed crops (maize, tomato, sunflower and quinoa), were clearly demonstrated when soils were amended with 20% compost, despite the very high soil electrical conductivity (EC). The role of compost amendment was not only to provide organic matter and nutrients to plants, but also to increase the ecological resilience under salinity stress, being compost rich in halo-(4.0 M NaCl)/thermo tolerant rhizobacteria (55 \({}^{\circ}\)C). The authors were able to isolate 13 rhizobacteria from the plant rhizosphere, cultivated in soil amended with compost and watered with high concentrations of NaCl; some of these showed several biochemical PGP features. The key role of PGPB was also highlighted in the paper of [PERSON] et al. [5]. In fact, even in this work, the authors aimed at isolating and characterizing halotolerant bacteria, associated with the rhizosphere and root tissues of _Scaevola ramossissima_ (Sm.) [PERSON], envisaging their application in saline agriculture. In this case, the endophytic and rhizosphere bacteria were isolated from wild and crop-cultivated plants, growing in different estuarine conditions. The isolated halotolerant strains, belonging to the _Salinicola_, _Pseudomonas_, _Oceanobacillus_, _Halomonas_, _Proviencia_, _Bacillus_, _Psychroacterium_ genera, also exhibited several plant growth-promoting traits. These kinds of collections represent a valuable resource that can be used to optimize the crop cultivation of plants, under different environmental conditions,and for the attenuation of salt stress in non-halophytes. The role of endophytic bacteria was further developed and expounded by [PERSON] et al. [6]. In their work, they isolated approximately 60 bacterial endophytes from three economically relevant plant species (cucumber, tomato and sorghum), cultivated in three different soils. Five of them were selected as plant growth promoters and were used to inoculate sorghum seeds. Following this, plant growth promotion activity was assessed on sorghum plants exposed to salinity stress.