Response Of Lettuce Research Articles

Identification and Preliminary Functional Analysis of Responsive Genes to Short-term Heat Stress in Lettuce

Lettuce is a commonly consumed vegetable worldwide, due to its crisp edible organs and rich nutrition. Heat stress is known to seriously threaten its growth and development. However, research on lettuce response to heat stress focusing on molecular aspects is limited. Therefore, we aimed to understand the complex molecular mechanisms underlying the regulation of lettuce plant response to heat stress (37 °C), by transcriptomic analysis of a heat-resistant lettuce variety (K482) following heat stress treatment for 1.5 and 3 days. A total of 3798 and 4121 differentially expressed genes (DEGs) were identified at 1.5 and 3 days vs. the control after heat treatment, respectively; they were mostly enriched in protein processing in the systemic lupus erythematosus, alcoholism, neurotrophin signaling pathways, and the cell cycle. Most DEGs were NACs, HSPs, MYBs, bHLHs, and WRKYs. Transcriptome analysis showed that the NAC domain transcription factor LsNAC28, which is associated with heat response, is up-regulated during heat stress and LsNAC28 inhibited yeast growth under heat stress (37 °C). These findings provide a basis to comprehensively understand the complex molecular mechanism of lettuce response to heat stress.

Trait component analysis of lettuce in response to daily light integrals at two growth stages

AbstractLittle is known about the relative impact of lighting duration and light intensity on lettuce production, as well as whether daily light integrals (DLIs) play a significant role during different plant growth stages. Four DLIs were tested: 8.64, 11.52, 12.96, and 17.28 mol m−2 day−1 as supplemental lighting, which were obtained from a combination of supplemental light intensities at 200 and 300 µmol m−2 day−1 for 12 and 16 h. Sunlight was used as control. A direct correlation was observed between DLIs and yield, total fresh weight, and total dry weight. Under supplemental lighting, relative growth rate (RGR) increased due to an increase in net assimilation rate (NAR) rather than in leaf area ratio (LAR). Plants in the seedling stage were more sensitive to an elevation in DLI than in the head stage. This was confirmed by a greater increase in NAR compared to their corresponding control under the same DLI. Increasing DLI also improved lettuce quality via reducing nitrate and increasing protein content. Higher DLIs (12.96 and 17.28 mol m−2 day−1) led to a decrease in maximum quantum yield of photosystem II and an increase in performance index. In conclusion, manipulating RGR through NAR adjustments proved to be more effective than changes in LAR, and adjusting supplemental DLI at each stage was necessary to achieve a larger NAR and, consequently, a larger RGR.

Improved morphological and yield responses of green lettuce (Lactuca sativa L.) grown with seaweed extract as a hydroponic nutrient solution

Sargassum polycystum is among the seaweed species in the Philippines that are considered coastal waste after drifting on the shorelines. Although there has been a report on the potential of S. polycystum as a biostimulant for certain crops, its utilization as a hydroponic nutrient solution is not yet thoroughly analyzed. Thus, a study utilizes various ratios of S. polycystum seaweed extract (SE) mixed with commercial hydroponic nutrient solution (CHNS) to the growth and yield of green leaf lettuce grown under the Kratky method of hydroponic system. Treatments are 100% CHNS and percentage replacements of CHNS with SE (25%, 50%, and 75%, respectively). The result shows a 10.53% increase in lettuce plant height grown under 25% and 50% SE compared to 100% CHNS. A similar result is also observed in the lettuce leaf width (14.29%), leaf length (7.14%), and plant weight (22.41%). Regarding root length, replacing 50% SE resulted in longer root length (44.83%) and more leaves (10%) compared to lettuce plants grown under 100% CHNS. However, replacement of SE beyond 50% is detrimental to leaf length and comparable to all growth and yield parameters with 100% CHNS. Regarding the return on investment, 50% SE replacement has the highest return of 98.62% compared to 100% CHNS, with 49.87% only for a projected six cropping cycles. Hence, a 50% replacement of CHNS with SE from its recommended rate can be suggested for more profitable production of green leaf lettuce under a hydroponic system.

Assessing the response lettuce and arugula to MC-LR-contaminated water irrigation: photosynthetic changes and antioxidant defense.

Irrigation of crops with cyanotoxin-contaminated water poses a significant risk to human health. The direct phytotoxic effects of microcystin-LR (MC-LR), one of the most toxic and prevalent microcystin variants in water bodies, can induce physiological stress and hinder crop development and production. This study investigated the impact of environmentally relevant concentrations of MC-LR (1 to 10µg L-1) on photosynthetic parameters and antioxidant response of lettuce (Lactuca sativa L.) and arugula (Eruca sativa L.) following irrigation with contaminated water. During the 15-day experiment, lettuce and arugula were exposed to various concentrations of MC-LR, and their photosynthetic rates, stomatal conductance, leaf tissue transpiration, and intercellular CO2 concentrations were measured using an infrared gas analyzer. These results suggest that the influence of MC-LR on gas exchange in crops is concentration-dependent, with notable disruptions during exposure and recovery tendency during detoxification. Antioxidant response analysis revealed that glutathione S-transferase (GST) and superoxide dismutase (SOD) activities were upregulated during the exposure phase in the presence of MC-LR. However, GST activity decreased during the detoxification phase in both crops, although the effects of the toxin at 10µg L-1 were still evident in arugula. The internal H2O2 concentration in the crops increased after exposure to MC-LR, showing a time- and concentration-dependent pattern, with an increase during the exposure phase (days 1-7) and a decrease during the detoxification phase (days 8-15). Irrigation of lettuce and arugula with MC-LR-contaminated water affected various aspects of the photosynthetic apparatus and antioxidant responses, which could influence the general health and productivity of exposed crops at environmentally relevant microcystin concentrations. Furthermore, investigation of additional vegetable species and long-term MC-LR exposure can be crucial for understanding the extent of contamination risk, detoxification mechanisms, and other parameters affecting these crops.

Evaluation of Growth, Yield and Quality of Head Lettuce in Response to Salicylic Acid Foliar Spraying

Evaluation of Growth, Yield and Quality of Head Lettuce in Response to Salicylic Acid Foliar Spraying

The Effect of Exogenous Selenium Supplementation on the Nutritional Value and Shelf Life of Lettuce

Lettuce (Lactuca sativa) is rich in vitamins, minerals, and bioactive components, serving as an important source of selenium (Se) intake for humans. This study investigated the effects of Se treatment on lettuce using different concentrations of sodium selenite (Na2SeO3), focusing on biomass, physiological indicators, nutritional composition, and physiological changes during storage. Through correlation analysis of the transcriptome and Se species, the absorption and conversion mechanisms of Se in lettuce were revealed. The results showed that Se treatment initially increased the chlorophyll content in lettuce, followed by a decrease. Soluble sugar, soluble protein, total phenols, and anthocyanins increased at low Se concentrations but decreased at high concentrations. Flavonoid content decreased only at 1 mg/L Se, while other treatments were higher than the control group. GSH content and superoxide dismutase, catalase, and peroxidase activities initially increased and then decreased, while malondialdehyde (MDA) content first decreased and then increased. Five Se species, including Se (IV), Se (VI), selenocysteine (SeCys2), selenomethionine (SeMet), and methylselenocysteine (MeSeCys), were detected in lettuce leaves after Se treatment, with SeMet being the most abundant. During storage, Se-treated lettuce exhibited lower weight loss, a*, b*, browning index, and color difference (ΔE) values compared to the control group. CAT and POD activities and GSH content also followed a trend of initial increase followed by a decrease. Transcriptome data analysis revealed that genes such as MYB1, RPK1, PTR44, NTRC, WRKY7, and CSLD3 were associated with the stress response of Se-treated lettuce.

Physiological and growth responses of lettuce plants submitted of 2,4-D simulated drift

Pesticide drift is due to the transport of the active ingredient to areas not targeted by spraying, causing negative effects on the sensitive crops’ development. The aim of this study was to evaluate lettuce response to simulated 2,4-D drift. Experiments were conducted in the greenhouse, in a randomized complete block design with four replications. The treatments consisted of nine different doses of the 2,4-D herbicide, which are: 0; 1.56; 3.125; 6.20; 12.5; 25; 50; 75; and 100% from the recommended dose (670 g a.a. ha-1). The application occurred when the lettuce plants had four to six true leaves. The analyzed variables were visual injury (phytotoxicity), development parameter (phyllochron), growth (rosette diameter and dry mass of the aerial part), and photosynthetic parameters (gas exchange). The lettuce crop showed high sensitivity to the 2,4-D herbicide, with the lowest dose resulting in significant phytotoxic damage to plants, and from 12.5% of the recommended 2,4-D dose, visual injuries were greater than 90%. The plants´ development and growth were negatively affected by the increased drift doses, culminating in enhanced phyllochron and reduction in rosette diameter and dry mass of the aerial part. The gas exchange of the crop was affected from 6.20% of the recommended dose, causing a reduction in the CO2 assimilation rate, stomatal conductance, transpiration rate and rubisco carboxylation efficiency.

Determination of the physiological response of lettuce to different irrigation water salinities (NaCl) and leaching fractions

Determination of the physiological response of lettuce to different irrigation water salinities (NaCl) and leaching fractions

Integrated transcriptomic and metabolomic analysis provides insights into cold tolerance in lettuce (Lactuca sativa L.)

The popular leafy vegetable lettuce (Lactuca sativa L.) is susceptible to cold stress during the growing season, which slows growth rate, causes leaf yellowing and necrosis, and reduced yield and quality. In this study, transcriptomic and metabolomic analyses of two cold-resistant lettuce cultivars (GWAS-W42 and F11) and two cold-sensitive lettuce cultivars (S13K079 and S15K058) were performed to identify the mechanisms involved in the cold response of lettuce. Overall, transcriptome analysis identified 605 differentially expressed genes (DEGs), including significant enrichment of genes involved in the flavonoid and flavonol (CHS, CHI, F3H, FLS, CYP75B1, HCT, etc.) biosynthetic pathways related to oxidation–reduction and catalytic activity. Untargeted metabolomic analysis identified fifteen flavonoid metabolites and 28 other metabolites potentially involved in the response to cold stress; genistein, quercitrin, quercetin derivatives, kaempferol derivatives, luteolin derivatives, apigenin and their derivatives accumulate at higher levels in cold-resistant cultivars. Moreover, MYBs, bHLHs, WRKYs and Dofs also play positive role in the low temperature response, which affected the expression of structural genes contributing to the variation of metabolites between the resistant and sensitive. These results provide valuable evidence that the metabolites and genes involved in the flavonoid biosynthetic pathway play important roles in the response of lettuce to cold stress.

Growth, phytochemical concentration, nutrient uptake, and water consumption of butterhead lettuce in response to hydroponic system design and growing season

Two hydroponic system designs (nutrient film technique: NFT, and deep water culture: DWC) were set up in a climate-controlled greenhouse to compare growth, nutrients and water uptake patterns, yield and quality of lettuce (Lactuca sativa cv. Butterhead) during fall (October through November) and summer (July-August) growing conditions. The research was conducted with four system replicates for each hydroponic design and each system contained nine lettuce plants. Plant photosynthetic properties, growth parameters, and irrigation solution nutrient concentrations were measured weekly. At the end of the production cycle, plants were harvested for leaf area, fresh and dry yield of shoots and roots, nutritional and phytochemical concentrations. In the study, DWC system had better water quality properties than NFT including less seasonal water temperature fluctuation, which supported lettuce with better photosynthetic rates, growth rate and fresh yield in fall. Tipburn symptoms were only observed in summer, and NFT grown lettuce had significantly lower shoot calcium and magnesium concentrations than DWC in both fall and summer seasons, which led to more severe tip burn symptom in summer. In addition, better water quality in DWC also benefited lettuce with higher antioxidant concentrations than NFT, which included 9.4 % higher vitamin C in fall, 34.6 % higher total carotenoids in fall, 40.6 % higher non-acidified phenols in fall, as well as 12.9 % higher total chlorophyll in summer. Although there were marginal differences in fresh yield, most types of mineral nutrients and antioxidants between DWC and NFT, DWC performed better than NFT with less tipburn in summer as well as increased yield, total carotenoids, vitamin C and non-acidified phenols in fall.

Response of lettuce grown in potting soil semi-solidified with agar

Response of lettuce grown in potting soil semi-solidified with agar

Boosting the resilience to drought of crop plants using wood distillate: A pilot study with lettuce (Lactuca sativa L.)

Increasingly severe drought driven by climate change is harming crop quality and productivity, making it crucial to find nature-based solutions like wood distillate (WD) to aid crops withstand these stressful conditions. This study investigated the effects of WD application on the growth and stress responses of lettuce (Lactuca sativa L.) under drought conditions. The experiment included periodic measurements of plant growth-related parameters and stress indices to evaluate the effectiveness of WD in mitigating drought-induced damage. The results showed a significant increase (13–26 %) in fresh biomass of the aboveground portion of lettuce treated with WD, indicating the potential of WD as a biostimulant to promote plant growth. In addition, treatment with WD led to a significant increase in total soluble protein content (14–28 %), showing a possible positive effect on protein synthesis. The enhancement of anti-radical activity (measured in terms of DPPH) following the application of WD up to 42 % reflected the ability of the plant to scavenge harmful reactive oxygen species and alleviate oxidative stress. The observed reduction (up to 19 % in comparison with control) in MDA content also confirmed the effectiveness of WD in protecting the integrity of plant cell membranes from oxidative damage. Despite the beneficial effects on anti-radical activity, the total content of the antioxidant compounds (phenols and flavonoids) decreased with the use of WD (5–14 %), most likely suggesting complex interactions between WD and the biosynthesis of these secondary metabolites. The study showed the positive effect of WD application on the growth and stress tolerance of lettuce plants under drought conditions. These results can provide new insights into sustainable agricultural practices and the potential application of WD as a nature-based and effective means to improve crop productivity, especially in water scarce areas.

Application of Chlorophyll Fluorescence Analysis Technique in Studying the Response of Lettuce (Lactuca sativa L.) to Cadmium Stress.

To reveal the impact of cadmium stress on the physiological mechanism of lettuce, simultaneous determination and correlation analyses of chlorophyll content and photosynthetic function were conducted using lettuce seedlings as the research subject. The changes in relative chlorophyll content, rapid chlorophyll fluorescence induction kinetics curve, and related chlorophyll fluorescence parameters of lettuce seedling leaves under cadmium stress were detected and analyzed. Furthermore, a model for estimating relative chlorophyll content was established. The results showed that cadmium stress at 1 mg/kg and 5 mg/kg had a promoting effect on the relative chlorophyll content, while cadmium stress at 10 mg/kg and 20 mg/kg had an inhibitory effect on the relative chlorophyll content. Moreover, with the extension of time, the inhibitory effect became more pronounced. Cadmium stress affects both the donor and acceptor sides of photosystem II in lettuce seedling leaves, damaging the electron transfer chain and reducing energy transfer in the photosynthetic system. It also inhibits water photolysis and decreases electron transfer efficiency, leading to a decline in photosynthesis. However, lettuce seedling leaves can mitigate photosystem II damage caused by cadmium stress through increased thermal dissipation. The model established based on the energy captured by a reaction center for electron transfer can effectively estimate the relative chlorophyll content of leaves. This study demonstrates that chlorophyll fluorescence techniques have great potential in elucidating the physiological mechanism of cadmium stress in lettuce, as well as in achieving synchronized determination and correlation analyses of chlorophyll content and photosynthetic function.

Growth performance and metabolic changes in lettuce inoculated with plant growth promoting bacteria in a hydroponic system

Crop cultivation in hydroponic systems is often exposed to both abiotic and biotic stresses, which impact growth. One possible approach to alleviating these stresses and improving plant growth is by utilizing plant growth-promoting bacteria (PGPB). Our previous study has shown the efficacy of two PGPB strains, Pseudomonas lundensis UB 53 and Pseudomonas migulae UB 54, in promoting growth and stimulating the generation of plant defense enzymes to mitigate biotic and abiotic stress in lettuce grown in a nutrient film technique (NFT) hydroponic system. Therefore, this study purposed to assess metabolic changes in lettuce in response to P. lundensis UB 53 and P. migulae UB 54 inoculation in a NFT hydroponic system. The results exhibited that these bacteria enhanced IAA accumulation and lettuce growth in a NFT hydroponic system. A total of 58 metabolites were detected in the root samples, including primary and secondary metabolites. It also influenced 12 metabolic pathways, with emphasis on five pathways, including the metabolism of alpha-linolenic acid, inositol phosphate, pyruvate, sulfur, and the phosphatidylinositol signaling system. These results highlight the significant roles of myo-inositol and acetic acid in metabolic pathways during the interaction between lettuce and PGPB.

Effects of polystyrene, polyethylene, and polypropylene microplastics on the soil-rhizosphere-plant system: Phytotoxicity, enzyme activity, and microbial community

The widespread presence of soil microplastics (MPs) has become a global environmental problem. MPs of different properties (i.e., types, sizes, and concentrations) are present in the environment, while studies about the impact of MPs having different properties are limited. Thus, this study investigated the effects of three common polymers (polystyrene, polyethylene, and polypropylene) with two concentrations (0.01% and 0.1% w/w) on growth and stress response of lettuce (Lactuca sativa L.), soil enzymes, and rhizosphere microbial community. Lettuce growth was inhibited under MPs treatments. Moreover, the antioxidant system, metabolism composition, and phyllosphere microbiome of lettuce leaves was also perturbed. MPs reduced phytase activity and significantly increased dehydrogenase activity. The diversity and structure of rhizosphere microbial community were disturbed by MPs and more sensitive to polystyrene microplastics (PSMPs) and polypropylene microplastics (PPMPs). In general, the results by partial least squares pathway models (PLS-PMs) showed that the presence of MPs influenced the soil-rhizosphere-plant system, which may have essential implications for assessing the environmental risk of MPs.

Composts of diverse green wastes improve the soil biological quality, but do not alleviate drought impact on lettuce (Lactuca sativa L.) growth

AbstractIntense soil cultivation and climate change have detrimental effects on soils. Solutions are needed to improve the biological quality and water holding capacity of agricultural soils. A greenhouse experiment was conducted to investigate the interactive effect of compost application and drought stress on a soil/plant system in order to determine the improvement of soil quality and plant growth and the alleviation of drought stress. Lettuce (Lactuca sativa L.) was grown under greenhouse conditions in a sandy soil with sufficient mineral fertilizer application to test the effect of five compost types (three made from municipal garden and park wastes with differing nutrient contents, one from municipal household waste, and one from farm plant residues) applied at 30 Mg ha−1 dry weight, with which we compared soil quality and plant growth to soil without compost application. Treatment pots were irrigated or subjected to drought conditions during the last 14 days of lettuce growth. Assays of potential N mineralization during 28 days, dehydrogenase and β‐glucosidase activities, and a phospholipid fatty acid (PLFA) analysis were performed to assess effects on soil biological quality. Gas exchange, leaf relative water content, biomass, nitrogen accumulation, and root tip growth of lettuce were measured to investigate compost and drought stress effects on lettuce physiology. All composts improved indices of soil biological quality significantly, except for fungal abundance, relative to soil without compost. The greatest increase was obtained from farm compost, which significantly increased potential nitrogen (N) mineralization and soil enzyme activities of β‐glucosidase and dehydrogenase by factors of 4, 2, and 43, respectively. Furthermore, soil with farm compost generally showed a higher abundance of soil microbial organisms compared with soil without compost, which could be related to its high cellulose and hemicellulose contents. The lowest abundance of microbial organisms was generally found in soil with garden and park waste compost with a medium nutrient content, which could be related to its low organic matter content. The beneficial effect of compost on soil biological quality did not lead to improved lettuce growth, which suggests that soil biological quality (ameliorated by compost application) is not important for a fast‐growing crop, such as lettuce, that is sufficiently fertilized. Drought stress reduced aboveground lettuce biomass, root tip growth, and the abundance of most soil microbial groups significantly, but compost in soil did not alleviate these negative effects. In conclusion, the farm compost made from grass–clover, straw, and vegetable residues is superior to garden and park waste and household waste composts in terms of beneficial effects on soil biological quality. Compost clearly improved soil biological quality, but did not influence lettuce's response to drought stress. The knowledge gained in this study is useful for producing tailor‐made compost with desired effects of improved soil biological quality.

Metabolic response of lettuce (Lactuca sativa L.) to polystyrene nanoplastics and microplastics after foliar exposure

Foliar exposure to polystyrene nanoplastics and microplastics exerted varied effects on the metabolism of lettuce (Lactuca sativa L.).

Postharvest Quality of Lettuce (Lactuca Sativa L.) as Influenced by Salinity Stress

Salinity is one of the abiotic stresses and one of the major constraints to plant growth, development, productivity, postharvest quality, and nutrition. Plant responses to high salinity affects its morphological and developmental aspects of growth as well as its physiological and biochemical processes. Lettuce is an important crop for human diet; however, it is moderately sensitive to salinity stress. Hence, this study was conducted to examine the response of lettuce to different salinity levels. The study was laid out in Randomized Complete Block Design (RCBD) replicated three times with five sodium chloride (NaCl) concentrations as treatments. This includes the control (water); 500 parts/million (ppm); 1,000 ppm; 5,000 ppm; and10,000 ppm. Results show that salinity stress did not significantly influence on yield, leaf moisture content, color deterioration, percent weight loss, wilting, texture, and Visual Quality Rating (VQR) of harvested lettuce. Furthermore, it also did not significantly influence on some biochemical properties specifically on initial pH and initial titratable acidity (TA), final total soluble solids (TSS) and TA, leaf chlorophyll, sugar, and starch content. Lettuce planted on potting media with various levels of salinity during it growth and development until harvesting significantly obtained a significantly lower initial TSS during postharvest analysis than those lettuce planted in potting media without any added salt content. Therefore, lettuce can still survive when planted in soil containing up to 10,000 ppm NaCl without impairing its growth, yield, physical characteristics, and some biochemical properties of harvested lettuce specifically on TA, chlorophyll, sugar, and starch content.

Lettuce Response to Enhanced Struvite Recovered from Faecal Sludge Effluent and the Probabilistic Health Risk Assessment of Heavy Metals Through the Intake of the Lettuce.

Precipitating magnesium ammonium phosphate (MAP) to include potassium (K) has been explored to improve the fertilizing ability of the product. The present study aims to precipitate a MAP that also contains K and determine the probable risk to human health through the daily consumption of lettuce cultivated with the enhanced struvite. Analysis of the precipitate revealed that adding cocoa bean husk as seed produced MAP with potassium (K) content. The concentration of the heavy metals in the fresh leaves (concentration range, safe limits in mg/kg) was Cu (6.14 – 12.13, 73.3), Cd (0.11 – 0.43, 0.2), Ni (0.44 – 0.85, 67.9), Pb (0.85 – 1.38, 0.3). The estimated daily intake of heavy metals via the consumption of lettuce grown with struvite was below the tolerable upper dietary intake levels. The 95th percentile of the hazard index for the control, NPK and struvite are 0.047, 0.605, (0.214 – 0.759) respectively. The struvite produced can significantly improve its performance as an alternate phosphorus fertilizer and also show if struvite is safe for use as a fertilizer.

The multifaceted response of lettuce (Lactuca sativa L.) to biofortification with iron

The multifaceted response of lettuce (Lactuca sativa L.) to biofortification with iron