Hydrogen peroxide and salt stress in radish: effects on growth, physiology, and root quality.

Hydrogen peroxide (H2O2) plays a central role in responses to salt stress, a major abiotic stress that impacts crop yield worldwide. Despite the evidence that H2O2 mitigates salt stress and improves post-harvest quality on several species, its effects on radish were not investigated so far. Thus, the objective of this study was to evaluate the exogenous application of H2O2 on salt stress mitigation of radish growth, physiology, and post-harvest quality. For this, radish plants were grown in pots for 30 days, being watered with non-saline (0.31 dS m-1) or saline water (120 mM NaCl, 12.25 dS m-1). Plants were leaf-sprayed weekly with water (control - 0 µM H2O2) or H2O2 (150 or 1500 µM) solutions. The experimental design was completely randomized in a 3 × 2 factorial scheme (H2O2 treatments × salt stress conditions). The growth, physiology (gas exchanges, photochemical efficiency, relative water content, electrolyte leakage, and the contents of chlorophylls and carotenoids), and post-harvest attributes of globular roots (color, anthocyanins, vitamin C, phenolic compounds, and soluble solids) were determined. Salt stress decreased gas exchanges and increased electrolyte leakage, which resulted in stunted radish growth, and increased the contents of antioxidants, such as anthocyanins, soluble solids, and vitamin C, improving globular root quality. Conversely, H2O2 did not mitigate salt stress effects on radish growth, photosynthetic capacity, and oxidative damages. Although H2O2 increased vitamin C under non-stressed condition, it was decreased under salt stress. Thus, we conclude that H2O2 did not mitigate salt stress on radish growth and quality. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-024-01476-z.

In Vitro Propagation of "Salsaparrilha" [Herreria salsaparrilha Mart. (Asparagaceae)]: An Antisyphilitic Medicinal Species.

An efficient procedure for in vitro propagation of Herreria salsaparrilha Martius was established from single-node explants (fourth and fifth nodes from apex to the base) derived from donor plants maintained under shading-house conditions. After surface sterilization, explants are inoculated in test tubes containing 15 mL of Murashige and Skoog (MS) medium without growth regulators. Cultures are maintained under 35 µmol m-2 s-1 irradiance, a 16/8-h light/dark light regime, at 26 ± 2 °C. The subcultures are carried out under the same conditions, adding 6-benzyladenine 1.0 mg/L and Phytagel® 2.8 g/L. Shoots are elongated and rooted by transferring individual shoots to half-strength MS medium without growth regulators. After 25-30 days, elongated rooted shoots are transferred to plastic pots containing 25-30 mL of sterile distilled water, covered with a transparent plastic bag, and kept under the same growth room conditions for 2 days. Plants are transferred to cups containing autoclaved and washed sand and kept in a shading house (50% light interception) for acclimatization. True-to-type adult plants were successfully recovered under ex vitro conditions.

Advances in Tissue Culture and Transformation Studies in Non-model Species: Passiflora spp. (Passifloraceae).

In this chapter, we report advances in tissue culture applied to Passiflora. We present reproducible protocols for somatic embryogenesis, endosperm-derived triploid production, and genetic transformation for such species knowledge generated by our research team and collaborators in the last 20 years. Our research group has pioneered the work on passion fruit somatic embryogenesis, and we directed efforts to characterize several aspects of this morphogenic pathway. Furthermore, we expanded the possibilities of understanding the molecular mechanism related to developmental phase transitions of Passiflora edulis Sims. and P. cincinnata Mast., and a transformation protocol is presented for the overexpression of microRNA156.

Advances in Tissue Culture and Transformation Studies in Non-model Species: Bixa orellana L. (Bixaceae).

Over the years, our team has dedicated significant efforts to studying a unique natural dye-producing species, annatto (Bixa orellana L.). We have amassed knowledge and established foundations that support the applications of gene expression analysis in comprehending in vitro morphogenic regeneration processes, phase transition aspects, and bixin biosynthesis. Additionally, we have conducted gene editing associated with these processes. The advancements in this field are expected to enhance breeding practices and contribute to the overall improvement of this significant woody species. Here, we present a step-by-step protocol based on somatic embryogenesis and an optimized transformation protocol utilizing Agrobacterium tumefaciens.

Pre-harvest application of sodium nitroprusside enhances storage root quality in red beet cultivated under normal and drought conditions.

BACKGROUND: The role of nitric oxide (NO) in plant stress tolerance, as well as in increasing post-harvest quality, has been extensively demonstrated in several fruits and vegetable crops; however, the effects of its pre-harvest application on post-harvest quality are still poorly documented. Therefore, the pre-harvest application of NO in red beet (Beta vulgaris subsp. vulgaris) plants cultivated under well-watered and drought conditions was evaluated to assess whether it improves the post-harvest quality of their storage roots. Red beet plants cultivated under well-watered (80% of water holding capacity) or drought condition (15% of water holding capacity) were sprayed weekly with water (control) or 100 µmol L-1 sodium nitroprusside (SNP), an NO donor. Sixty-six days after sowing, red beet roots were harvested, and root yield, total sugar yield, reducing sugars, non-reducing sugars, proteins, lipids, root ashes, root moisture, soluble solids, titratable acidity, pH, vitamin C, total phenolics, total betalains, betacyanins, betaxanthins and antioxidant capacity were determined. RESULTS: While drought led to a reduction in root yield, sugars, lipids and titratable acidity, it increased phenolic compounds, betalains and the antioxidant capacity of beets. SNP reversed the negative effects of drought on sugar, lipid and organic acid contents and increased antioxidant capacity independent of stress. CONCLUSION: Pre-harvest SNP treatment reversed drought-induced yield reductions in beets, while boosting bioactive compounds and antioxidant capacity. It also enhanced vitamin C content independently, indicating its dual role in stress mitigation and beet quality improvement. Future research should explore other crops and stress conditions. © 2024 Society of Chemical Industry.

Salicylic Acid and Water Stress: Effects on Morphophysiology and Essential Oil Profile of Eryngium foetidum.

The exogenous application of bioregulators, such as salicylic acid (SA), has exhibited promising outcomes in alleviating drought stress. Nevertheless, its impact on culantro (Eryngium foetidum L.) remains unexplored. Thus, the aim of this study was to assess how SA impacts the growth, morphophysiology, and essential oil composition of culantro when subjected to drought. To achieve this, culantro plants were grown under three different watering regimes: well-watered, drought-stressed, and re-watered. Additionally, they were either treated with SA (100 µM) or left untreated, with water serving as the control. SA application did not mitigate the effects of drought in biomass production but increased biomass, leaf number, leaf area, and photosynthetic pigments under well-irrigated and re-watered conditions. After a drought period followed by re-watering, plants recovered membrane integrity independently of SA application. Water stress and the exogenous application of SA also modulated the profile of essential oils. This is the first report about SA and drought affecting growth and essential oil composition in culantro.

Chemodiversity of Dissolved Soil Organic Matter from Amazon Rainforest as Influenced by Deforestation.

Many biogeochemical processes are modulated by dissolved organic matter (DOM), but the drivers influencing the chemodiversity of DOM compounds in Amazonian soils are poorly understood. It has also been theorized whether deforestation controls the decline of DOM. In this study, we collected soil samples from thirty sites across different regions of Brazil's Legal Amazon, and we investigated the trade-offs among soil physical-chemical properties and DOM chemodiversity. We employed optical spectroscopy, Fourier transform ion cyclotron resonance, and multivariate analysis. Our results indicated that, despite variations in land use and soil physical-chemical properties, factors such as the deforested site, geometric mean diameter, weighted average diameter, and soil organic carbon were the main influencers of DOM chemodiversity variation. These findings highlight the importance of considering DOM chemodiversity as closely related to land use and its potential use in developing deforestation models for predicting soil quality decline in Brazil's Legal Amazon.

Plant age-dependent dynamics of annatto pigment (bixin) biosynthesis in Bixa orellana.

Age affects the production of secondary metabolites, but how developmental cues regulate secondary metabolism remains poorly understood. The achiote tree (Bixa orellana L.) is a source of bixin, an apocarotenoid used in diverse industries worldwide. Understanding how age-dependent mechanisms control bixin biosynthesis is of great interest for plant biology and for economic reasons. Here we overexpressed miRNA156 (miR156) in B. orellana to comprehensively study the effects of the miR156-SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) module on age-dependent bixin biosynthesis in leaves. Overexpression of miR156 in annatto plants (miR156ox) reduced BoSPL transcript levels, impacted leaf ontogeny, lessened bixin production, and increased abscisic acid levels. Modulation of expression of BoCCD4-4 and BoCCD1, key genes in carotenoid biosynthesis, was associated with diverting the carbon flux from bixin to abscisic acid in miR156ox leaves. Proteomic analyses revealed an overall low accumulation of most secondary metabolite-related enzymes in miR156ox leaves, suggesting that miR156-targeted BoSPLs may be required to activate several secondary metabolic pathways. Our findings suggest that the conserved BomiR156-BoSPL module is deployed to regulate leaf dynamics of bixin biosynthesis, and may create novel opportunities to fine-tune bixin output in B. orellana breeding programs.

Irrigation level and substrate type on the acclimatization and development of mandacaru (Cereus jamacaru DC.): an emblematic cactus from Brazilian semiarid region.

Mandacaru is a cactus with great socioeconomic potential, but lack of information about its cultivation hinders its domestication. Here, we aimed to evaluate the acclimatization and vegetative development of mandacaru under different substrates and irrigation levels. For this, seeds inoculated in vitro were grown for 120 days, being transplanted to pots containing four types of substrate (S1-caatinga soil + gravel; S2-washed sand + organic matter + soil + charcoal; S3-washed sand + cattle manure + soil + sand; S4-commercial organic substrate). Pots were irrigated with 100% of the field capacity (FC) once-a-week, or with 50% FC twice-a-week, and kept in a greenhouse for six months. The experimental design was completely randomized, in a 4 × 2 factorial scheme, with six replications. Plant height and diameter, axial and radial growth rate, fresh and dry mass of stem and root, water content, and photosynthetic pigments were determined. Growth was affected mainly by the substrate, with S4 resulting in higher growth and pigment content, while S1 was impaired and S2 and S3 resulted in intermediate growth. The use of S4 and 100% FC once per week was the best condition for mandacaru.

Water stress and exogenous carnitine on growth and essential oil profile of Eryngium foetidum L.

Water stress influences plant growth and metabolism. Carnitine, an amino acid involved in lipid metabolism, has been related to responses of plants to abiotic stresses, also modulating their metabolites. Culantro (Eryngium foetidum L.) is a perennial herb, rich in essential oils, native to Latin America, commonly used due to its culinary and medicinal properties. Here, we investigated the effect of exogenous carnitine on morphophysiology and the essential oil profile of culantro plants under water stress. For this, plants were grown under three water conditions: well-watered, drought stress, and re-watered; and sprayed with exogenous carnitine (100 µM) or water (control). Culantro growth was impaired by drought and enhanced by re-watering. Carnitine, in turn, did not reverse drought effects on growth, and impaired the growth of re-watered plants, also improving photosynthetic pigment content. Water conditions and carnitine application changed the essential oil profile of the plants. Drought and re-watering improved the production of eryngial, which was even increased with exogenous carnitine in re-watered plants. In addition, hydroquinone was only produced with the combination of re-watering and carnitine application. The application of exogenous carnitine can be a strategy to induce the production of essential oil compounds with cosmetic and pharmaceutical importance in culantro. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03757-y.