https://hdl.handle.net/10481/31191 2026-04-11T22:27:49Z https://hdl.handle.net/10481/110953 Metabolic and physiological coordination of drought response and recovery in Porlieria chilensis Estay, Maria Jose; Sanhueza, Carolina; Fernández Del-Saz, Néstor; Bascuñan Godoy, Luisa; Ortiz Gutiérrez, José During drought stress and subsequent recovery, plants adjust their water–carbon dynamics, typically increasing intrinsic water-use efficiency (iWUE) and mobilizing non-structural carbohydrate (NSC) pools. However, in tree species, the physiological and metabolic changes underlying these adjustments remains poorly understood because their larger size, slower turnover rates, and complex compartmentalization of carbon and water fluxes make difficult to capture coordinated whole-plant responses under natural drought–recovery cycles. In Porlieria chilensis, a species currently classified as vulnerable, we performed short- and long-term drought experiments, followed by recovery conditions in juvenile trees to investigate sugar-mediated responses associated with the dynamics of NSC, iWUE and primary metabolites by combining enzymatic activities, δ¹³C and δ¹⁸O, respiration rates and omics technologies. Long-term drought increased significantly iWUEmes (integrating mesophyll conductance and δ¹³C) due to stomatal closure, and decreased starch content coinciding with an inactivation of ADP-glucose pyrophosphorylase (AGPase) activity. Short-term recovery restored photosynthetic activities to pre-stress levels, while long-term recovery triggered the upregulation of several sugar-related enzymes to replenish NSC pools, and the accumulation of metabolites involved in osmotic regulation and polyamine metabolism. We concluded that a sugar futile cycle may help to sustain leaf carbon metabolism, supporting osmotic balance and carbon reserves during prolonged drought and recovery in this species. Overall, these findings improved understanding of carbon dynamics and stress-induced metabolic imprinting in woody species, providing insights for restoration strategies and predicting plant responses to climate change. https://hdl.handle.net/10481/108631 A Genome-Wide Association Study Reveals QTLs and Candidate Genes Associated with the Carotenoid Content in the Flesh of Cucurbita pepo L. Fruit López, Alba; García, Alicia; Castro-Cegrí, Alejandro; Segura, María; Benítez, Álvaro; Palma, Francisco; Garrido Garrido, Dolores; Martínez, Cecilia; Jamilena, Manuel Considering the importance of carotenoids in the human diet, their enhancement is a key trait in current breeding programs. This study assessed lutein, zeaxanthin, α-carotene, and β-carotene levels in the flesh of mature fruits from 257 global C. pepo accessions. Lutein and β-carotene were the most prevalent, with top accessions identified for each carotenoid. A panel of 120 accessions with reliable carotenoid contents and genetic diversity was analyzed using 23,111 GBS-generated SNPs in genome-wide association studies (GWAS). Three genomic regions (qtl1, qtl3, and qtl13) on chromosomes 1, 3, and 13 were significantly linked to carotenoid levels, with alternative alleles increasing the carotenoid content, leading to yellowish–orange flesh. Seven candidate genes were identified: CpTIC56, CpHSHP70, and CpPDL8, which regulate carotenoid biosynthesis in chloroplasts; CpSPX and CpPHO1, associated with phosphate homeostasis and carotenoid buildup; CpMYB106, co-expressed with carotenoid biosynthesis genes; and a CpPPR RNA-binding protein. RNA-seq data from yellow- and white-fleshed fruits supported their involvement in carotenoid accumulation. These results improve our understanding of the genetic control of carotenoid buildup in C. pepo fruit, supporting breeding efforts for improved nutritional quality. https://hdl.handle.net/10481/108194 Ionomic Profile and Nutrient Use Efficiency in Sunflower Plants Treated with Plant-Derived Biostimulant Rich in Trigonelline Izquierdo Ramos, María José; Atero Calvo, Santiago; Navarro Morillo, Iván; Pérez-Millán, Rafael; Blasco León, Begoña In recent decades, the use of biostimulants has increased with the aim of creating an alternative to the use of chemical fertilizers and achieving sustainable agriculture. In this study, sunflower plants (Helianthus annuus L. cv. neoma) were grown under controlled conditions, and four trigonelline-rich extracts were applied as biostimulants through root and foliar applications. The plant growth parameters, nutrient concentrations, root metabolic activity, and nutrient use efficiency were evaluated. The results showed that the foliar application of extract 4 significantly improved the aboveground biomass and leaf area compared with the control treatments, with values of 44.30 g FW and 680.22 cm2 , respectively. Moreover, this extract enhanced nutrient accumulation. Meanwhile, foliar application of extract 3 improved macronutrient and micronutrient concentrations, as in the case of phosphorus, which increased by 74.2%, and iron, which increased by 107.3%. Root applications of extracts 3 and 4 increased apparent nutrient recovery, whereas foliar applications of extracts 3 and 4 improved internal nutrient use and productivity indices. Overall, the treatments showed no phytotoxicity and promoted growth, nutrient absorption, and nutrient use efficiency, with the best results observed in foliar treatments with high trigonelline content. These findings indicate that biostimulants with trigonelline-rich extracts could improve crop yield, reduce the use of fertilizer, and contribute to more sustainable agricultural systems. https://hdl.handle.net/10481/108062 Selenium nanoparticles enhance plant tolerance to salinity and protect from postharvest fungal infection Sierra, Sandra; Ortega-Muñoz, Mariano; Sánchez Aranda, Patricia; Castro-Cegrí, Alejandro; Sampedro Quesada, María Inmaculada; Pérez-Bueno, María Luisa; Garrido Garrido, Dolores; Palma Martín, Francisco José Nanotechnology is an emerging alternative to conventional phytochemicals for improving crop productivity and maintaining the postharvest fruit quality sustainably. In this work, selenium nanoparticles (SeNPs) were synthesized by reduction of sodium selenite with ascorbic acid and stabilized with the natural polysaccharide dextrin. These SeNPs averaged 27 nm in diameter and featured an amorphous structure, exhibiting a high antioxidant capacity at ≥ 10 mg L− 1 , and effective scavenging activity for reactive oxygen species (hydroxyl radical and hydrogen peroxide) at concentrations as low as 1 mg L− 1 . Applied to seedlings of edible leaf plant (lettuce), these SeNPs enhanced plant growth, particularly root growth, and salinity tolerance, being 5 mg L− 1 the optimum concentration. The SeNPs also showed antifungal activity against Botrytis cinerea, the main causal agent of gray mold in postharvest fruits: in vitro, SeNPs at 1 mg L− 1 caused a complete growth inhibition of B. cinerea, while in vivo, SeNPs at 10 mg L− 1 proved effective in preventing gray mold on grapes, raspberries and strawberries. As selenium could be incorporated into edible parts of the plant, and due to the interest in selenium fortification, the toxicity of SeNPs in humans was checked using Caenorhabditis elegans as a model system. Their low toxicity in this animal model, together with the positive effect on seedlings growth and salinity tolerance, and postharvest antifungal activity, lay the foundation for future research in the implementation of these SeNPs in the agri-food industry. https://hdl.handle.net/10481/107577 Comparative Effects of Iron Nanoparticles, Chelates, and Iron Sulfate on Biomass, Yield, and Nitrogen Assimilation in Spinach Franco-Lagos, Cristina L.; Navarro León, Eloy; Ochoa-Chaparro, Erick H.; Chávez-Mendoza, Celia; Muñoz-Márquez, Ezequiel; Guevara-Aguilar, Alexandro; Terrazas-Gómez, Marina; Sánchez, Esteban Foliar application with iron is a promising strategy for improving nitrogen nutrition and productivity in horticultural crops. In this study, the effect of the foliar application of iron oxide nanoparticles (IONPs) compared to conventional iron sources on physiological, biochemical, and productive parameters of Spinacia oleracea L. was evaluated. Plants were treated with different concentrations (0, 25, 50, and 100 ppm) of IONPs, ferric sulfate (FS), and iron chelate (IC). Biomass, yield, nitrate reductase enzyme activity, soluble protein and amino acid contents, SPAD values, and photosynthetic pigments were analyzed. The results showed that IONPs, particularly at 50–100 ppm, promoted significant increases in biomass (50% more than the control), yield (47%), and nitrate reductase enzyme activity (NRmax) (246%) compared to the control (0 ppm) without negatively affecting pigment levels or leaf physiological condition. Likewise, increases in soluble protein and photosynthetic pigment levels were observed, reflecting improved nitrogen assimilation and photosynthetic efficiency. These findings suggest that IONPs represent an efficient and safe alternative to traditional Fe sources, contributing to the development of sustainable agricultural systems aimed at improving the nutritional value and productivity of leafy crops.