The geomagnetic field (GMF) is an environmental factor affecting the mineral nutrient uptake of plants and a contributing factor for efficient iron (Fe) uptake in Arabidopsis seedlings. Understanding the mechanisms underlining the impact of the environment on nutrient homeostasis in plants requires disentangling the complex interactions occurring among nutrients. In this study we investigated the effect of GMF on the interplay between iron (Fe) and sulfur (S) by exposing Arabidopsis thaliana plants grown under single or combined Fe and S deficiency, to near-null magnetic field (NNMF) conditions. Mineral analysis was performed by ICP-MS and capillary electrophoresis, whereas the expression of several genes involved in Fe and S metabolism and transport was assayed by qRT-PCR. The results show that NNMF differentially affects (i) the expression of some Fe- and S-responsive genes and (ii) the concentration of metals in plants, when compared with GMF. In particular, we observed that Cu content alteration in plant roots depends on the simultaneous variation of nutrient availability (Fe and S) and MF intensity (GMF and NNMF). Under S deficiency, NNMF-exposed plants displayed variations of Cu uptake, as revealed by the expression of the SPL7 and miR408 genes, indicating that S availability is an important factor in maintaining Cu homeostasis under different MF intensities. Overall, our work suggests that the alteration of metal homeostasis induced by Fe and/or S deficiency in reduced GMF conditions impacts the ability of plants to grow and develop.

Background Rice is one of the most salt sensitive crops at seedling, early vegetative and reproductive stages. Varieties with salinity tolerance at seedling stage promote an efficient growth at early stages in salt affected soils, leading to healthy vegetative growth that protects crop yield. Saltol major QTL confers capacity to young rice plants growing under salt condition by maintaining a low Na+/K+ molar ratio in the shoots. Results Marker-assisted backcross (MABC) procedure was adopted to transfer Saltol locus conferring salt tolerance at seedling stage from donor indica IR64-Saltol to two temperate japonica varieties, Vialone Nano and Onice. Forward and background selections were accomplished using polymorphic KASP markers and a final evaluation of genetic background recovery of the selected lines was conducted using 15,580 SNP markers obtained from Genotyping by Sequencing. Three MABC generations followed by two selfing, allowed the identification of introgression lines achieving a recovery of the recurrent parent (RP) genome up to 100% (based on KASP markers) or 98.97% (based on GBS). Lines with highest RP genome recovery (RPGR) were evaluated for agronomical-phenological traits in field under non-salinized conditions. VN1, VN4, O1 lines were selected considering the agronomic evaluations and the RPGR% results as the most interesting for commercial exploitation. A physiological characterization was conducted by evaluating salt tolerance under hydroponic conditions. The selected lines showed lower standard evaluation system (SES) scores: 62% of VN4, and 57% of O1 plants reaching SES 3 or SES 5 respectively, while only 40% of Vialone Nano and 25% of Onice plants recorded scores from 3 to 5, respectively. VN1, VN4 and O1 showed a reduced electrolyte leakage values, and limited negative effects on relative water content and shoot/root fresh weight ratio. Conclusion The Saltol locus was successfully transferred to two elite varieties by MABC in a time frame of three years. The application of background selection until BC3F3 allowed the selection of lines with a RPGR up to 98.97%. Physiological evaluations for the selected lines indicate an improved salinity tolerance at seedling stage. The results supported the effectiveness of the Saltol locus in temperate japonica and of the MABC procedure for recovering of the RP favorable traits.

The use of sulfur (S) stable isotopes to study S metabolism in plants is still limited by the relatively small number of studies. It is generally accepted that less S stable isotope discrimination occurs during sulfate (SO42–) uptake. However, S metabolism and allocation are expected to produce separations of S stable isotopes among the different plant S pools and organs. In this study, we measured the S isotope composition of the main S pools of rice plants grown under different SO42– availabilities in appropriate closed and open hydroponic-plant systems. The main results indicate that fractionation against 34S occurred during SO42– uptake. Fractionation was dependent on the amount of residual SO42– in the solution, showing a biphasic behavior related to the relative expression of two SO42– transporter genes (OsSULTR1;1 and OsSULTR1;2) in the roots. S isotope separations among S pools and organs were also observed as the result of substantial S isotope fractionations and mixing effects occurring during SO42– assimilation and plant S partitioning. Since the S stable isotope separations conserve the memory of the physiological and metabolic activities that determined them, we here underline the potential of the 32S/34S analysis for the detailed characterization of the metabolic and molecular processes involved in plant S nutrition and homeostasis.

IntroductionAppropriate postharvest treatment, as well as adequate conditions of storage, can be adopted to elongate the lifespan of cut flowers. Thidiazuron (TDZ), a substituted phenylurea, and 1-methylcycloproene (1-MCP), a non-toxic inhibitor of ethylene perception, are nowadays substances commonly used to prevent early damage caused by senescence and to delay chlorophyll degradation. Ranunculus asiaticus L. is cultivated for cut flower production and is highly sensitive to ethylene and leaf yellowing. In this study, the effect of different pulse-tratment in prolonging cut ranunculus vase life was analyzed.MethodsTDZ 10 µM, 1-MCP 500 ppb, and a combination of both were applied for 24 hours after harvest. The effect of the treatments was evaluated by performing non-destructive (% loss of fresh weight, chlorophyll a fluorescence, in vivo chlorophyll content, and Nitrogen Flavonol Index – NFI) and destructive (chlorophyll, carotenoids, anthocyanins concentration, and phenolic index) analyses at 0, 1, 12, and 14 days from treatments. Results and DiscussionFlower wilting was delayed by 4 days in 1-MCP + TDZ 10 µM treatments, which also reduced weight loss and chlorophyll degradation compared to controls. The effectiveness of these compounds in preventing senescence has been confirmed by the decreased biosynthesis of phenolic compounds.