Systemic acquired resistance is a powerful mechanism, based on the salicylic acid (SA) signaling pathway, which allows plants to resist to a wide range of pathogens. High SA, moreover, plays a key role in plant tolerance to abiotic stress. It seems, therefore, desirable to supply analogs of SA or stimulate the production of endogenous SA. Unfortunately, the chemical substances or physical means used for this effect often display a variable efficacy. After providing a review of them, we defend three major ideas: (i) plant resistance inducers (PRIs) must be combined for higher efficacy, notably for exploiting synergic effects between the SA and other signaling pathways, (ii) disease pressure can be reduced by exploiting the fungicidal properties displayed by some PRIs, (iii) biostimulants and crop management techniques should be used to ensure that plants have the resources they need to synthesize the compounds and structures required for efficient and lasting resistance. Some PRIs could also be used for their biostimulant effects in stress conditions. It could be concluded that holistic approaches which jointly address the issues of defense and tolerance stimulation, disease pressure and resource availability in plants are the ones that will allow for substantial reduction in fungicide use without sacrificing crop performance.

Seedling pre‐emergence is a critical phase of development for successful crop establishment because of its susceptibility to environmental conditions. In a context of reduced use of inorganic fertilizers, the genetic bases of the response of seedlings to nitrate supply received little attention. This issue is important even in legumes where nitrate absorption starts early after germination, before nodule development. Natural variation of traits characterizing seedling growth in the absence or presence of nitrate was investigated in a core collection of 192 accessions of Medicago truncatula. Plasticity indexes to the absence of nitrate were calculated. The genetic determinism of the traits was dissected by genome‐wide association study (GWAS). The absence of nitrate affected seed biomass mobilization and root/shoot length ratio. However, the large range of genetic variability revealed different seedling performances within natural diversity. A principal component analysis (PCA) carried out with plasticity indexes highlighted four physiotypes of accessions differing in relationships between seedling elongation and seed biomass partitioning traits in response to the absence of nitrate. Finally, GWAS revealed 45 associations with single or combined traits corresponding to coordinates of accessions on PCA, as well as two clusters of genes encoding sugar transporters and glutathione transferases surrounding loci associated with seedling elongation traits.

Introduction: The current study aimed to explore the in vitro antioxidant, anti-inflammatory, antidiabetic, and dermatoprotective properties of lemon peel essential oil (EO). Methods: The chemical composition of lemon EOs extracted from the lemon of three cities in Morocco was investigated using gas chromatography-mass spectrometry (GC-MS) analysis. The antioxidant property was estimated by two complementary tests: Ferric ion reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH). The in vitro anti-inflammatory activity was assessed by the inhibition of albumin denaturation and proteinase. Inhibitory properties of α-glucosidase and α-amylase were used to reveal the antidiabetic activity of lemon peel EOs. Dermatoprotective property was evaluated by the tyrosinase inhibition method. Results: In addition to high amounts of polyphenols and flavonoids, GC-MS analysis of lemon peel EOs demonstrated the presence of D-limonene, β–pinene, and γ-terpinene as the main compounds in the three samples studied. Lemon peel EOs exhibited significant antioxidant activities by IC50 values ranging from 40.57 µg/mL to 100.22 µg/mL and 113.63 µg/mL to 180.90 µg/mL obtained by DPPH and FRAP tests, respectively. in vitro inhibition of enzymes involved in inflammatory response revealed that lemon peel EOs presented remarkable inhibitory activities against albumin denaturation (230.48 µg/mL>IC50<341.13 µg/mL) and proteinase (199.70 µg/mL>IC50<307.05 µg/mL). Moreover, lemon peel EOs demonstrated powerful inhibition of α-amylase and α-glucosidase with various IC50 values (1689.06 µg/ mL>IC50>4000 µg/mL and 1021.58 µg/mL>C50<2467.62 µg/mL), respectively. These EOs also revealed significant inhibition of tyrosinase with IC50 values ranging from 248.42 μg/ mL to 378.02 μg/mL. Conclusion: These results revealed that lemon peel EOs might constitute a new product with beneficial biological abilities against the mentioned complications.

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