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The escalating risks of drought and salinization due to climate change and anthropogenic activities are a major global concern. Rhizobium–legume (herb or tree) symbiosis is proposed as an ideal solution for improving soil fertility and rehabilitating arid lands, representing a crucial direction for future research. Consequently, several studies have focused on enhancing legume tolerance to drought and salinity stresses using various techniques, including molecular-based approaches. These methods, however, are costly, time-consuming, and cause some environmental issues. The multiplicity of beneficial effects of soil microorganisms, particularly plant growth-promoting bacteria (PGPB) or plant-associated microbiomes, can play a crucial role in enhancing legume performance and productivity under harsh environmental conditions in arid zones. PGPB can act directly or indirectly through advanced mechanisms to increase plant water uptake, reduce ion toxicity, and induce plant resilience to osmotic and oxidative stress. For example, rhizobia in symbiosis with legumes can enhance legume growth not only by fixing nitrogen but also by solubilizing phosphates and producing phytohormones, among other mechanisms. This underscores the need to further strengthen research and its application in modern agriculture. In this review, we provide a comprehensive description of the challenges faced by nitrogen-fixing leguminous plants in arid and semi-arid environments, particularly drought and salinity. We highlight the potential benefits of legume–rhizobium symbiosis combined with other PGPB to establish more sustainable agricultural practices in these regions using legume–rhizobium–PGPB partnerships. [ABSTRACT FROM AUTHOR]

Tuber aestivum, commonly known as the summer truffle, is typically found in various parts of Europe where it grows naturally. However, its presence in Portugal was not confirmed until now. The first fruit bodies were collected in April 2024 at stone pine stands (Alenquer and Arruda dos Vinhos, Lisbon) and in June at holm oak stands (Salir, Faro). These specimens are characterized by hypogeous, subglobose, black ascomata with a peridium surface covered with pyramidal warts. Ascopores are subglobose-to-broadly ellipsoid, distinctively ornamented, usually 1–6 per asci. According to the results of the internal transcribed spacer (ITS) rDNA sequence analysis, these specimens form a well-supported group within the Aestivum clade, with T. aestivum being the closest phylogenetic taxon. This remarkable discovery opens up new opportunities for truffle exploitation in Portugal thanks to the summer truffle's gastronomical value and high market prices. [ABSTRACT FROM AUTHOR]

Rhizobia strains expressing the enzyme 1-aminocyclopropane-1-carboxylate ( ACC) deaminase have been reported to display an augmented symbiotic performance as a consequence of lowering the plant ethylene levels that inhibit the nodulation process. Genes encoding ACC deaminase ( acdS) have been studied in Rhizobium spp.; however, not much is known about the presence of acdS genes in Mesorhizobium spp. The aim of this study was to assess the prevalence and phylogeny of acdS genes in Mesorhizobium strains including a collection of chickpea-nodulating mesorhizobia from Portugal. ACC deaminase genes were detected in 10 of 12 mesorhizobia type strains as well as in 18 of 18 chickpea Mesorhizobium isolates studied in this work. No ACC deaminase activity was detected in any Mesorhizobium strain tested under free-living conditions. Despite the lack of ACC deaminase activity, it was possible to demonstrate that in Mesorhizobium ciceri UPM- Ca7T, the acdS gene is transcribed under symbiotic conditions. Phylogenetic analysis indicates that strains belonging to different species of Mesorhizobium, but nodulating the same host plant, have similar acdS genes, suggesting that acdS genes are horizontally acquired by transfer of the symbiosis island. This data, together with analysis of the symbiosis islands from completely sequenced Mesorhizobium genomes, suggest the presence of the acdS gene in a Mesorhizobium common ancestor that possessed this gene in a unique symbiosis island. [ABSTRACT FROM AUTHOR]

A survey was conducted during the months of April–June 2003 in the northeast Portugal (Bragança district) in order to characterize the hemoparasite population of an autochthonous Mirandesa breed of Bos taurus. The polymerase chain reaction (PCR) analysis of the bovine blood revealed that 3 out of 116 animals were infected with Theileria and/or Babesia parasites, while reverse line blot hybridisation (RLB) analysis showed that these animals were infected with Theileria buffeli/orientalis. Cloning and sequencing confirmed the RLB results. Database sequence searches combined with phylogenetic analysis of the partial 18S ribosomal RNA gene sequences obtained enabled us to place the parasites in question as members of the T. buffeli/orientalis group, confirming the PCR/RLB diagnosis. [Copyright &y& Elsevier]

Rhizobia are soil bacteria able to form symbioses with legumes and fix atmospheric nitrogen, converting it into a form that can be assimilated by the plant. The biological nitrogen fixation is a possible strategy to reduce the environmental pollution caused by the use of chemical N-fertilizers in agricultural fields. Successful colonization of the host root by free-living rhizobia requires that these bacteria are able to deal with adverse conditions in the soil, in addition to stresses that may occur in their endosymbiotic life inside the root nodules. Stress response genes, such as otsAB , groEL , clpB , rpoH play an important role in tolerance of free-living rhizobia to different environmental conditions and some of these genes have been shown to be involved in the symbiosis. This review will focus on stress response genes that have been reported to improve the symbiotic performance of rhizobia with their host plants. For example, chickpea plants inoculated with a Mesorhizobium strain modified with extra copies of the groEL gene showed a symbiotic effectiveness approximately 1.5 fold higher than plants inoculated with the wild-type strain. Despite these promising results, more studies are required to obtain highly efficient and tolerant rhizobia strains, suitable for different edaphoclimatic conditions, to be used as field inoculants., Competing Interests: Conflict of Interest: All authors declare no conflicts of interest in this paper.