Plant protection with beneficial microbes is considered to be a promising alternative to chemical control of pests and pathogens. Beneficial microbes can boost plant defences via induced systemic resistance (ISR), enhancing plant resistance against future biotic stresses. Although the use of ISR-inducing microbes in agriculture seems promising, the activation of ISR is context-dependent: it often occurs only under particular biotic and abiotic conditions, thus making its use unpredictable and hindering its application. Although major breakthroughs in research on mechanistic aspects of ISR have been reported, ISR research is mainly conducted under highly controlled conditions, differing from those in agricultural systems. This forms one of the bottlenecks for the development of applications based on ISR-inducing microbes in commercial agriculture. We propose an approach that explicitly incorporates context-dependent factors in ISR research to improve the predictability of ISR induction under environmentally variable conditions. Here, we highlight how abiotic and biotic factors influence plant–microbe interactions in the context of ISR. We also discuss the need to raise awareness in harnessing interdisciplinary efforts between researchers and stakeholders partaking in the development of applications involving ISR-inducing microbes for sustainable agriculture.

Although Ficus carica L. (fig) is one of the most resistant fruit tree species to salinity, no comprehensive studies are currently available on its molecular responses to salinity. Here we report a transcriptome analysis of F . carica cv. Dottato exposed to 100 mM sodium chloride for 7 weeks, where RNA-seq analysis was performed on leaf samples at 24 and 48 days after the beginning of salinization; a genome-derived fig transcriptome was used as a reference. At day 24, 224 transcripts were significantly up-regulated and 585 were down-regulated, while at day 48, 409 genes were activated and 285 genes were repressed. Relatively small transcriptome changes were observed after 24 days of salt treatment, showing that fig plants initially tolerate salt stress. However, after an early down-regulation of some cell functions, major transcriptome changes were observed after 48 days of salinity. Seven weeks of 100 mM NaCl dramatically changed the repertoire of expressed genes, leading to activation or reactivation of many cell functions. We also identified salt-regulated genes, some of which had not been previously reported to be involved in plant salinity responses. These genes could be potential targets for the selection of favourable genotypes, through breeding or biotechnology, to improve salt tolerance in fig or other crops.

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BackgroundFicus carica L. Objectives to determine survival, growth, biomass distribution, leaf gas exchange, and water relations. Methods typical experiment plants were irrigated with saline water at either 50, 100, or 200 mM NaCl concentration for seven-eight weeks. In year 1 we added two additional concentrations: 300 (then adjusted after one week to 250 for the remaining six weeks) and Results plant water status. Leaf photosynthetic rate (A) and stomatal conductance (g s ) decreased as salinity was increased beyond 50 mM NaCl after 18 days of stress in both years. Leaf chlorophyll concentrations were unaltered by salinity. Shoot growth stopped after two weeks of salinization at 100 mM NaCl and beyond. Leaf beginning of salinization due to extensive leaf drop. Plant dry weight for the 50, 100, and 200 mM NaCl respectively. The canopy-to-root ratio (both fresh and range. Conclusions of safe growth beyond previously reported threshunder saline conditions provided tolerant cultivars are planted.