Red and blue light are both vital factors for plant growth and development. We examined how different ratios of red light to blue light (R/B) provided by light-emitting diodes affected photosynthetic ...performance by investigating parameters related to photosynthesis, including leaf morphology, photosynthetic rate, chlorophyll fluorescence, stomatal development, light response curve, and nitrogen content. In this study, lettuce plants (Lactuca sativa L.) were exposed to 200 μmol⋅m(-2)⋅s(-1) irradiance for a 16 h⋅d(-1) photoperiod under the following six treatments: monochromatic red light (R), monochromatic blue light (B) and the mixture of R and B with different R/B ratios of 12, 8, 4, and 1. Leaf photosynthetic capacity (A max) and photosynthetic rate (P n) increased with decreasing R/B ratio until 1, associated with increased stomatal conductance, along with significant increase in stomatal density and slight decrease in stomatal size. P n and A max under B treatment had 7.6 and 11.8% reduction in comparison with those under R/B = 1 treatment, respectively. The effective quantum yield of PSII and the efficiency of excitation captured by open PSII center were also significantly lower under B treatment than those under the other treatments. However, shoot dry weight increased with increasing R/B ratio with the greatest value under R/B = 12 treatment. The increase of shoot dry weight was mainly caused by increasing leaf area and leaf number, but no significant difference was observed between R and R/B = 12 treatments. Based on the above results, we conclude that quantitative B could promote photosynthetic performance or growth by stimulating morphological and physiological responses, yet there was no positive correlation between P n and shoot dry weight accumulation.
•AMF outperforms phosphate in favouring nutrient uptake.•AMF boosts photosynthesis & secondary metabolism.•Transcriptome analysis reveals molecular bases of several AMF effects.•AMF triggers distinct ...gene expression compared to phosphate.•Gene expression correlates with plant traits.
Lettuce (Lactuca sativa L.) is an annual autogamous diploid plant belonging to Asteraceae and is among the top ten most profitable crops worldwide due to its nutritional value. Nevertheless, lettuce is an intensive crop with high input demand, especially fertilisers, both in soil-bound and soilless culture, with negative impact on the environment and production costs. In this context, arbuscular mycorrhizal symbioses could help to reduce the impact of fertilisers, improving plant nutrition, particularly regarding phosphorus, and contributing to growing healthier plants for human consumption. In our work, we compared lettuce plants (cv. Salinas) grown in soilless culture with optimal phosphorus concentration in the nutrient solution, with sub-optimal phosphorus nutrition and with plants grown with sub-optimal phosphorus concentration and inoculated with the fungus Funneliformis mosseae before transplanting.
Higher levels of primary and secondary metabolites along with increased biomass were observed for mycorrhizal plants compared to lettuces grown with optimal and sub-optimal concentrations of phosphate. Gene expression profile was analysed in both roots and leaves, and transcriptomic values were associated with growth and biochemical parameters. Three-thousand and fifty-seven genes were differentially regulated by mycorrhizal symbiosis and 2,606 genes by optimal phosphate nutrition.
Different genes related to photosynthesis, solute transport, metabolism of phytohormones, redox homeostasis, and transcriptional regulation resulted differentially regulated between culture conditions. Mycorrhizal plants also boosted the activation of genes involved in phenylpropanoids and carotenoids metabolism. In conclusion, growth, biochemical, and transcriptomic data show that symbiotic plants benefit both plant growth and leaf content of health promoting phytochemicals through genetic pathways that largely differed those activated in plants grown with optimal phosphorus supply.
Currently, there is a lack of information about the influence of foliar-applied nanoplastics on crop growth and nutritional quality. To fill the knowledge gap, soil-grown lettuces (Lactuca sativa L.) ...were foliar-exposed to polystyrene nanoplastics (PSNPs) at 0, 0.1 and 1 mg/L for one month. Foliar exposure to PSNPs significantly decreased the dry weight, height, and leaf area of lettuce by 14.3%–27.3%, 24.2%–27.3%, and 12.7%–19.2%, respectively, compared with the control. Similarly, plant pigment content (chlorophyll a, b and carotenoid) was considerably reduced (9.1%, 8.7%, 12.5%) at 1 mg/L PSNPs. However, the significant increase in electrolyte leakage rate (18.6%–25.5%) and the decrease in total antioxidant capacity (12.4%–26%) were the key indicators of oxidative stress in lettuce leaves, demonstrating the phytotoxicity of PSNPs by foliar exposure. In addition, the remarkable reduction in micronutrients and essential amino acids demonstrated a decrease in nutritional quality of lettuce caused by PSNPs. Besides, SEM and TEM analysis indicated the possible absorption of PSNPs through leaves stoma and the translocation downwards to plant roots. This study provides new information about the interaction of airborne NPs with plants. It also warns against atmospheric NPs pollution that the adverse effects of airborne NPs on crop production and food quality should be assessed as a matter of urgency.
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•Foliar exposure to PSNPs significantly decreased plant biomass, height, and leaf area of lettuce.•Foliage exposure to PSNPs caused oxidative stress and impaired antioxidant system.•PSNPs could be absorbed by lettuce leaves and then transported down to plant roots.•PSNPs reduced the micronutrients and essential amino acids contents in lettuce.
•Biostimulant effect on metabolic profile of salt-stressed lettuce plants was explored.•Biostimulant improved crop tolerance to salinity.•Biostimulant enhanced nitrogen metabolism and Fv/Fm-ratio ...efficiency.•Metabolomic analysis revealed significant changes related to biostimulant application.
Plant-derived protein hydrolysates represent new biostimulant products able to improve crop tolerance to abiotic stresses. The aim of the study was to determine growth, root morphology, SPAD index, chlorophyll fluorescence, leaf mineral composition, and metabolic profiling of greenhouse lettuce either untreated or treated (root or leaf-root application) with a plant-derived protein hydrolysate. For foliar application, plants were sprayed with a solution containing 2.5mlL−1 of biostimulant, whereas for root application, 100mL of solution with the same concentration was applied to the growing medium at weekly intervals. Lettuce plants were supplied with two nutrient solutions: non-salt control (1mM NaCl) or 25mM NaCl. Salt stress decreased shoot and root dry biomass, SPAD index, chlorophyll fluorescence, leaf mineral composition and increased foliar proline concentration. Root and leaf-root application of the biostimulant increased fresh yield, dry biomass and root dry weight of lettuce under salinity conditions. This was associated with an improvement of plant nitrogen metabolism and an increase of the Fv/Fm-ratio efficiency in biostimulant-treated plants. Oxidative stress mitigation, increase in osmolytes, changes in sterols and terpenes composition, as well as the less expected increase in glucosinolates were also observed in biostimulant-treated plants grown under saline conditions. The present study proves that the application of plant-derived protein hydrolysate increases plant performance when plants are grown under salinity conditions. The most favorable metabolic profile was obtained when biostimulant was applied to both roots and leaves.
The Colorado River is contaminated with perchlorate concentrations of 1.5-8 microgram/L, an anion linked to thyroid dysfunction. Over 90% of the lettuce (Lactuca sativa L.) consumed during the winter ...months in the United States is produced in the Lower Colorado River region. Studies were conducted in this region to survey the potential for lettuce perchlorate accumulation and estimate potential human exposure to perchlorate from lettuce. Total uptake of perchlorate in the above-ground plant of iceberg lettuce was approximately 5 g/ha. Exposure estimates ranged from 0.45 to 1.8 microgram/day depending on lettuce types and trimming. For all lettuce types, hypothetical exposures were less than 4% of the reference dose recommended by the National Academy of Sciences. Results show the relative iodide uptake inhibition potential because of lettuce nitrate was 2 orders of magnitude greater than that associated with the corresponding trace levels of perchlorate. These data support the conclusion that potential perchlorate exposures from lettuce irrigated with Colorado River water are negligible relative to acute or long-term harmful amounts.
Microbial inoculants such as
-based products are receiving great interest among researchers and agricultural producers for their potential to improve crop productivity, nutritional quality as well as ...resistance to plant pathogens/pests and numerous environmental stresses. Two greenhouse experiments were conducted to assess the effects of
-based biostimulants under suboptimal, optimal and supraoptimal levels of nitrogen (N) fertilization in two leafy vegetables: Iceberg lettuce (
L.) and rocket (
Mill.). The yield, nutritional characteristics, N uptake and mineral composition were analyzed for each vegetable crop after inoculation with
strains
(GV41) or
(T22), and results were compared to non-inoculated plants. In addition, the effect of the
-based biostimulants on microbes associated with the rhizosphere in terms of prokaryotic and eukaryotic composition and concentration using DGGE was also evaluated.
-based biostimulants, in particular GV41, positively increased lettuce and rocket yield in the unfertilized plots. The highest marketable lettuce fresh yield was recorded with either of the biostimulant inoculations when plants were supplied with optimal levels of N. The inoculation of rocket with GV41, and to a lesser degree with T22, elicited an increase in total ascorbic acid under both optimal and high N conditions.
GV41 increased N-use efficiency of lettuce, and favored the uptake of native N present in the soil of both lettuce and rocket. The positive effect of biostimulants on nutrient uptake and crop growth was species-dependent, being more marked with lettuce. The best biostimulation effects from the
treatments were observed in both crops when grown under low N availability. The
inoculation strongly influenced the composition of eukaryotic populations in the rhizosphere, in particularly exerting different effects with low N levels in comparison to the N fertilized plots. Overall, inoculations with
may be considered as a viable strategy to manage the nutrient content of leafy horticulture crops cultivated in low fertility soils, and assist vegetable growers in reducing the use of synthetic fertilizers, developing sustainable management practices to optimize N use efficiency.
Lettuce (Lactuca sativa L.) is a globally important leafy vegetable that can be grown worldwide. Due to the rapid growth of population and the human desire to progress, there have been a lot of ...studies made by researchers, especially in genetic engineering. Improvements in regeneration system and transformation methodology have helped to increase the transformation efficiency and stable expression of transgenes in lettuce. Lettuce transgenic research carried out so far has mainly focused on using lettuce bioreactor to produce pharmaceutical protein and vaccines, improving nutritional and physiological value of lettuce. There are no comprehensive and detailed reviews available combining research developments with major regeneration system and basic genetic transformation in lettuce. This is an attempt to overview the progress in regeneration system, genetic transformation and biotechnological applications in the last decades as well as future implications.
•Cos lettuce plants were grown under irradiation patterns in which spectral photon flux density distribution changes over time.•Growth was promoted by shifting the irradiation times of blue and red ...lights.•Diurnal PPFD change contributed to the growth promoting effects.•Blue and red light monochromatic irradiation contributed to elongation of leaves.
This study examined the growth and morphology of cos lettuce (Lactuca sativa L.) to ascertain the effects of irradiation patterns with combinations of blue and red LED light, with spectral photon flux density changing with a period of 24h. In experiment 1, plants were grown under irradiation patterns in which plants were irradiated with blue and red LED lights at a PPFD of 90μmolm−2s−1 for 14h per day respectively. The red LED light irradiation starting time was simultaneous to or delayed 1, 4, or 7h from the blue LED light irradiation starting time. Results showed that the shoot fresh weight of plants grown under irradiation patterns with red LED light irradiation being delayed 4 or 7h from blue LED light irradiation was significantly greater than that under irradiation patterns with blue and red LED light irradiation starting simultaneously. This result showed that the growth of plants can be promoted merely by temporally shifting the irradiation hours of blue and red LED lights. We then conducted experiments to assess the mechanism of the observed growth-promoting effect from viewpoints of the diurnal PPFD change and duration of blue and red light monochromatic irradiation. The results of these experiments revealed that the diurnal PPFD change contributed to the growth-promoting effect and that blue and/or red light monochromatic irradiation increased the total leaf area of plants.
O substrato utilizado na produção de alface (Lactuca sativa L.), exerce papel primordial, no desenvolvimento inicial da planta. Neste sentido, com o presente trabalho objetivou-se avaliar a produção ...de mudas de alface em função de diferentes combinações de substratos. O experimento foi implantado em um delineamento inteiramente casualizado, com seis repetições. Constituídas por 24 mudas cada. Utilizou-se a variedade de alface Elba. Determinou-se o número de folhas (NF) em unidades de cada planta; comprimento de parte aérea (CPA) em cm; comprimento da raiz (CR) em cm; massa fresca da parte aérea (MFPA) e a massa fresca da raiz (MFRA) foram pesadas em balança analítica com precisão de 0,001g e os resultados obtidos registrados em g. planta-1. Foram avaliados quatro substratos, sendo um a própria terra, e três alternativos que foram escolhidos devido a sua disponibilidade na região: cama de frango, palha de arroz carbonizada, esterco de gado. Para todas as avaliações, ao final do ciclo da alface, de todos os outros substratos orgânico o que teve um maior valor significativo para desenvolvimento da cultura, foi o que continha terra preta + cama de frango.
Epidemiological studies have shown that regular consumption of fruits and vegetables is associated with reduced risk of chronic diseases. Vegetables can provide vitamins, phenolics, flavonoids, ...minerals and dietary fibers for optimal health benefits. However, some nutrients contained in many fruits and vegetables cannot meet of the complete nutrition need in the human body. Biotechnology has the potential to improve the nutritional value of crops. Considering the high consumption of romaine lettuce in human diet worldwide, the objective of study is to enhance the contents of vitamin C, phenolics and antioxidant activity in lettuce leaves by genetic engineering techniques. The gene expression level, vitamin C content, total phenolics, as well as total and cellular antioxidant activities were analyzed by real-time PCR, HPLC, FolinaCiocalteu, Hydro-PSC and CAA methods, respectively. The bio-fortification of genetically engineered lettuce increased vitamin C up to 48.94 A- 1.34 mg/100 g FW following the increased over-expression of At GLDH. This is almost a 3.2-fold increase as the content when compared with wild type lettuce (p < 0.05). In addition, phenolic compounds in transgenic lettuce contained 120.4 A- 1.62 mg GA equiv./100 g FW, almost double the phenolic content of the wild type. Total antioxidant activities were 735.4 A- 47.7 ?mol vitamin C equiv./100 g FW, cellular antioxidant activities were 7.33 A- 0.86 ?mol quercetin equiv./100 g FW (PBS wash) and 18.14 A- 0.68 ?mol quercetin equiv./100 g FW (No PBS wash) in transgenic lettuce, respectively, 1.5, 4 and twofold increases when compared with the wild type. This study suggests that bio-fortification by genetic engineering has great potential to improve vitamin C, phenolic contents and antioxidant activity in lettuce.
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