Seed priming mitigates high salinity impact on germination of bread wheat (Triticum aestivum L.) by improving carbohydrate and protein mobilization.

Salinity is increasingly considered as a major environmental issue, which threatens agricultural production by decreasing yield traits of crops. Seed priming is a useful and cost-effective technique to alleviate the negative effects of salinity and to enable a fast and uniform germination. In this context, we quantified the effects of priming with gibberellic acid (GP), calcium chloride (CP), and mannitol (MP) on seed germination of three bread wheat cultivars and investigated their response when grown at high salinity conditions (200 mM NaCl). Salt exposure strongly repressed seed imbibition and germination potential and extended germination time, whereas priming enhanced uniformity and seed vigor. Seed preconditioning alleviated the germination disruption caused by salt stress to varying degrees. Priming mitigating effect was agent-dependent with regard to water status (CP and MP), ionic imbalance (CP), and seed reserve mobilization (GP). Na+ accumulation in seedling tissues significantly impaired carbohydrate and protein mobilization by inhibiting amylase and proteases activities but had lesser effects on primed seeds. CP attenuated ionic imbalance by limiting sodium accumulation. Gibberellic acid was the most effective priming treatment for promoting the germination of wheat seeds under salt stress. Moreover, genotypic differences in wheat response to salinity stress were observed between varieties used in this study. Ardito, the oldest variety, seems to tolerate better salinity in priming-free conditions; Aubusson resulted the most salt-sensitive cultivar but showed a high germination recovery under priming conditions; Bologna showed an intermediate behavior.

Marker-Assisted Introgression of the Salinity Tolerance Locus Saltol in Temperate Japonica Rice.

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.

Insight into Composition of Bioactive Phenolic Compounds in Leaves and Flowers of Green and Purple Basil.

Basil (Ocimum basilicum L.) is a culinary, medicinal, and ornamental plant appreciated for its antioxidant properties, mainly attributed to high content of rosmarinic acid. This species also includes purple varieties, characterized by the accumulation of anthocyanins in leaves and flowers. In this work, we compared the main morphological characteristics, the antioxidant capacity and the chemical composition in leaves, flowers, and corollas of green ('Italiano Classico') and purple ('Red Rubin' and 'Dark Opal') basil varieties. The LC-ESI-MS/MS analysis of individual compounds allowed quantifying 17 (poly)phenolic acids and 18 flavonoids, differently accumulated in leaves and flowers of the three varieties. The study revealed that in addition to rosmarinic acid, basil contains several members of the salvianolic acid family, only scarcely descripted in this species, as well as, especially in flowers, simple phenolic acids, such as 4-hydroxybenzoic acid and salvianic acid A. Moreover, the study revealed that purple leaves mainly contain highly acylated anthocyanins, while purple flowers accumulate anthocyanins with low degree of decoration. Overall, this study provides new biochemical information about the presence of not yet characterized bioactive compounds in basil that could contribute to boosting the use of this crop and to gaining new knowledge about the roles of these compounds in plant physiology.

Evaluation of Borage Extracts As Potential Biostimulant Using a Phenomic, Agronomic, Physiological, and Biochemical Approach.

Biostimulants are substances able to improve water and nutrient use efficiency and counteract stress factors by enhancing primary and secondary metabolism. Premise of the work was to exploit raw extracts from leaves (LE) or flowers (FE) of Borago officinalis L., to enhance yield and quality of Lactuca sativa 'Longifolia,' and to set up a protocol to assess their effects. To this aim, an integrated study on agronomic, physiological and biochemical aspects, including also a phenomic approach, has been adopted. Extracts were diluted to 1 or 10 mL L-1, sprayed onto lettuce plants at the middle of the growing cycle and 1 day before harvest. Control plants were treated with water. Non-destructive analyses were conducted to assess the effect of extracts on biomass with an innovative imaging technique, and on leaf photosynthetic efficiency (chlorophyll a fluorescence and leaf gas exchanges). At harvest, the levels of ethylene, photosynthetic pigments, nitrate, and primary (sucrose and total sugars) and secondary (total phenols and flavonoids) metabolites, including the activity and levels of phenylalanine ammonia lyase (PAL) were assessed. Moreover, a preliminary study of the effects during postharvest was performed. Borage extracts enhanced the primary metabolism by increasing leaf pigments and photosynthetic activity. Plant fresh weight increased upon treatments with 10 mL L-1 doses, as correctly estimated by multi-view angles images. Chlorophyll a fluorescence data showed that FEs were able to increase the number of active reaction centers per cross section; a similar trend was observed for the performance index. Ethylene was three-fold lower in FEs treatments. Nitrate and sugar levels did not change in response to the different treatments. Total flavonoids and phenols, as well as the total protein levels, the in vitro PAL specific activity, and the levels of PAL-like polypeptides were increased by all borage extracts, with particular regard to FEs. FEs also proved efficient in preventing degradation and inducing an increase in photosynthetic pigments during storage. In conclusion, borage extracts, with particular regard to the flower ones, appear to indeed exert biostimulant effects on lettuce; future work will be required to further investigate on their efficacy in different conditions and/or species.

Cell wall metabolism of peaches and nectarines treated with UV-B radiation: a biochemical and molecular approach.

BACKGROUND: Ultra-violet B (UV-B) radiation has been shown to improve, at least in selected genotypes, both the health-promoting potential and the aesthetic properties of tomato and peach fruits during their post-harvest period. The effects of post-harvest UV-B treatment on the cell-wall metabolism of peaches and nectarines (Prunus persica L. Batsch) were assessed in this study. Three cultivars, Suncrest (melting flesh, MF) and Babygold 7 (non-melting flesh, NMF) peaches and Big Top (slow melting, SM) nectarine, differing in the characteristics of textural changes and softening during ripening, were analysed. RESULTS: The effects of UV-B differ in relation to the cultivar considered. In MF 'Suncrest' fruit, UV-B treatment significantly reduced the loss of flesh firmness despite the slight increase in the presence and activity of endo-polygalacturonase. The activity of exo-polygalacturonase increased as well, while endo-1,4-ß-D-glucanase/ß-D-glucosidase, ß-galactosidase and pectin methylesterase were substantially unaffected by the treatment. The UV-B-induced reduction of flesh softening was paralleled by the inhibition of PpExp gene transcription and expansin protein accumulation. The UV-B treatment did not induce differences in flesh firmness between control and UV-B-treated NMF 'Babygold 7' and SM 'Big Top' fruit. CONCLUSION: Based on these results, post-harvest UV-B treatment may be considered a promising tool to improve shelf-life and quality of peach fruit.

Cinnamyl alcohol dehydrogenases in the mesocarp of ripening fruit of Prunus persica genotypes with different flesh characteristics: changes in activity and protein and transcript levels.

Development of fruit flesh texture quality traits may involve the metabolism of phenolic compounds. This study presents molecular and biochemical results on the possible role played by cinnamyl alcohol dehydrogenase (CAD; EC 1.1.1.195) during ripening [S3, S4 I (pre-climacteric) and S4 III (climacteric) stages] of peach [Prunus persica (L.) Batsch] fruit with different flesh firmness [non-melting flesh (NMF) 'Oro A'/melting flesh (MF) 'Springcrest' and 'Sanguinella'] and color (blood-flesh Sanguinella). A total of 24 putative full-length PRUPE_CAD genes were identified (in silico analysis) in the peach genome. The most abundant CAD isoforms, encoded by genes located on scaffolds 8 and 6, were probed by specifically developed anti-PRUPE_CAD sc8 and by anti-FaCAD (PRUPE_CAD sc6) polyclonal antibodies, respectively. PRUPE_CAD sc8 proteins (SDS-PAGE and native-PAGE/western blot) appeared responsible for the CAD activity (in vitro/in-gel assays) that increased with ripening (parallel to PRUPE_ACO1 transcripts accumulation and ethylene evolution) only in the mesocarp of Oro A and blood-flesh Sanguinella. Accumulation of PRUPE_CAD sc8 transcripts (semi-quantitative RT-PCR) occurred in all three cultivars, but in Oro A and Springcrest it was not always accompanied by that of the related proteins, suggesting possible post-transcriptional regulation. Flesh firmness, as well as levels of lignin, total phenolics and, where present (Sanguinella), anthocyanins, declined with ripening, suggesting that, at least in the studied peach cultivars, CAD activity is related to neither lignification nor differences in flesh firmness (NMF/MF). Further studies are necessary to clarify whether the high levels of CAD activity/expression in Sanguinella play a role in determining the characteristics of this blood-flesh fruit.

Peach fruit ripening: A proteomic comparative analysis of the mesocarp of two cultivars with different flesh firmness at two ripening stages.

A proteomic analysis was conducted on peach fruit mesocarp in order to better elucidate the biochemical and physiological events which characterize the transition of fruit from the "unripe" to the "ripe" phase. The first goal of the present work was to set-up a protocol suitable for improving protein extraction from peach mesocarp. The use of freeze-dried powdered tissue, together with the addition of phenol prior to the extraction with an aqueous buffer, significantly increased the protein yield and the quality of 2-DE gels. The proteomic profiles of the mesocarp from peach fruit of a non-melting flesh (NMF; 'Oro A') and a melting flesh (MF; 'Bolero') cultivar, at "unripe" and "ripe" stages as defined by some parameters typical of ripening, were then analyzed. The comparative analysis of the 2-DE gels showed that in NMF and MF peaches the relative volumes of 53 protein spots significantly changed in relation to both the ripening stage ("unripe" versus "ripe") and/or the genetic background of the cultivar ('Oro A' versus 'Bolero'). Thirty out of the 53 differently abundant spots were identified by LC-ESI-MS/MS. The analysis revealed enzymes involved in primary metabolism (e.g. C-compounds, carbohydrates, organic acids and amino acids) and in ethylene biosynthesis as well as proteins involved in secondary metabolism and responses to stress. Among these, 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) appeared to be one of the proteins with the largest change in relative abundance during the fruit transition from the pre-climacteric ("unripe") to the climacteric ("ripe") phase. Other proteins, such as S-adenosylmethionine synthetase and ß-cyanoalanine synthase involved in ethylene metabolism, were also identified. Moreover, the changes in the relative abundances of a sucrose synthase and an α-amylase suggested differences between the two cultivars in the carbohydrate import activity of ripe fruit. The different accumulation of a few typical ROS-scavenger enzymes suggested that a higher oxidative stress occurred in MF with respect to NMF fruit. This result, together with data concerning the levels of total proteins and free amino acids and those regarding proteins involved in the maintenance of tissue integrity, was consistent with the hypothesis that the last phase of ripening in MF fruit is characterized by the appearance of a senescence status. The present study appears to define well some of the biochemical and physiological events that characterize the ripening of peach and, at the same time, provides interesting indications that could be employed in future marker assisted selection (MAS) programmes aimed to obtain MF fruits with higher ability to preserve tissue functionality maintaining for a longer time their organoleptic characteristics.