Owing to the high interspecific biodiversity, halophytes have been regarded as a tool for understanding salt tolerance mechanisms in plants in view of their adaptation to climate change. The present study addressed the physiological response to salinity of six halophyte species common in the Mediterranean area: Artemisia absinthium, Artemisia vulgaris, Atriplex halimus, Chenopodium album, Salsola komarovii, and Sanguisorba minor. A 161-day pot experiment was conducted, watering the plants with solutions at increasing NaCl concentration (control, 100, 200, 300 and 600 mM). Fresh weight (FW), leaf stomatal conductance (GS), relative water content (RWC) and water potential (WP) were measured. A principal component analysis (PCA) was used to describe the relationships involving the variables that accounted for data variance. A. halimus was shown to be the species most resilient to salinity, being able to maintain FW up to 300 mM, and RWC and WP up to 600 mM; it was followed by C. album. Compared to them, A. vulgaris and S. komarovii showed intermediate performances, achieving the highest FW (A. vulgaris) and GS (S. komarovii) under salinity. Lastly, S. minor and A. absinthium exhibited the most severe effects with a steep drop in GS and RWC. Lower WP values appeared to be associated with best halophyte performances under the highest salinity levels, i.e., 300 and 600 mM NaCl.

Salicornia europaea, a halophytic species, was investigated to assess its ability to withstand salinity during seed germination, and to identify suitable indices to interpret salt tolerance at this delicate stage. Seed germination indices (germination percentage (GP), germination energy (GE), germination value (GV), coefficient of germination velocity (CVG), germination rate index (GRI), germination peak value (GPV), mean germination time (MGT), and time to 50% germination (T₅₀)) were calculated under increasing salinity (0, 100, 200, 300, 400, and 600 mM NaCl). Principal component analysis (PCA) was used to describe the relationships involving the variables that account for data variance. Two salinity thresholds were identified (100 and 600 mM NaCl) determining significant decreases in all the indices, except for T₅₀ and MGT. In fact, PCA based on generated correlation circle showed significant negative correlations (r close to −1) between salt stress and GP, GE, GRI, PV, GV, and CVG, whereas no correlation was observed with T₅₀ and MGT (r close to zero). Based on this, GP, GE, GRI, PV, GV, and CVG can be considered useful traits to assess salt tolerance during germination in S. europaea, while T₅₀ and MGT, that were not affected by the range of salinity levels investigated, should not be used for this purpose.

The concept of essential derivation refers to cases where a new variety is obtained from an initial variety (IV), of which it retains the expression of the essential characteristics resulting from the genotype or combination of genotypes of the IV. Protecting plant breeder's rights can be facilitated by identifying a species‐specific threshold level of similarity above which the new variety could be suspected as essentially derived (EDV). Amplified fragment length polymorphisms and simple sequence repeats proved suitable for measuring genetic similarity. Three approaches have been proposed for the definition of thresholds. According to the ‘calibration principle’, the critical level to discriminate EDVs is defined based on similarities among closely related genotypes. Adopting the ‘tail principle’, the threshold is placed at a given percentile of the distribution of the similarities within a reference population of independent genotypes. Finally, with the ‘pedigree principle’, the threshold is set starting from the a priori definition of breeding techniques that lead to EDVs. The tools and the approaches described in this review represent the basis for developing protocols useful in handling disputes of essential derivation.

Trait purity is a key factor for the successful utilization of biotech varieties and is currently assessed by analysis of individual seeds or plants. Here we propose a novel PCR-based approach to test trait purity that can be applied to bulk samples. To this aim the insertion site of a transgene is characterized and the corresponding sequence of the wild-type (wt) allele is used as diagnostic target for amplification. As a demonstration, we developed a real-time quantitative PCR method to test purity of glyphosate tolerant (Roundup Ready®, RR) soybean.