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RNA-seq analysis of leaf lettuce treated with 100 μmol L⁻¹ melatonin at high temperature during the growth period (the control group did not receive exogenous melatonin under the same conditions). (A) In 100 μmol L⁻¹ melatonin treatment (HM), the leaf developmental stages of phenotypes changed significantly at 0, 6, 9, 15, 18, and 27 days with different stem lengths, and whole plants were characterized. Scale bars = 5 cm. (B) In the control group that did not have exogenous melatonin (H), the leaf developmental stages of phenotypes changed significantly on 0, 6, 9, 15, 18, and 27 days with different stem lengths, and whole plants were characterized. Scale bars = 5 cm. (C) Volcano plot visualizing differentially expressed genes (DEGs). The DEGs are shown in red and green. The x-axis represents the fold change in HM6 vs. H6, HM96 vs. H9, HM15 vs. H15, HM18 vs. H18 and HM27 vs. H27 (on a log2 scale), and the y-axis represents the negative log10-transformed p values (p < 0.05) of the t test for determining differences between the samples. (D) Cluster analysis of DEGs during different leaf treatments.
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High temperature is one of the primary environmental stress factors affecting the bolting of leaf lettuce. To determine the potential role of melatonin in regulating high-temperature induced bolting in leaf lettuce (Lactuca sativa L.), we conducted melatonin treatment of the bolting-sensitive cultivar “S39.” The results showed that 100 μmol L⁻¹ mel...
Citations
... Altas temperaturas são um dos principais fatores de estresse ambiental que afetam o pendoamento da alface (Chen et al., 2022), fato que compromete tanto a qualidade quanto a produção (Hao et al., 2022). Observa-se que um menor comprimento de caule resulta da adaptação da planta a elevadas temperaturas, que leva a uma maior lentidão no início do alongamento do caule e ao prolongamento da fase vegetativa, resultando em maior período de cultivo no campo, com uma maior produtividade. ...
... Altas temperaturas são um dos principais fatores de estresse ambiental que afetam o pendoamento da alface (Chen et al., 2022), fato que compromete tanto a qualidade quanto a produção (Hao et al., 2022). Observa-se que um menor comprimento de caule resulta da adaptação da planta a elevadas temperaturas, que leva a uma maior lentidão no início do alongamento do caule e ao prolongamento da fase vegetativa, resultando em maior período de cultivo no campo, com uma maior produtividade. ...
O cultivo de alface em hidroponia é crescente no Brasil o que faz com que se torne necessário a realização de estudos que avaliem as cultivares disponíveis no mercado em diversos locais e ambientes de cultivo, visto que algumas podem apresentar variações no desempenho agronômico em função de condições climáticas. Este estudo teve por objetivo avaliar o desempenho agronômico de cultivares de alface do grupo solta crespa em sistema de cultivo hidropônico em dois diferentes ambientes de cobertura: estufa coberta com polietileno de baixa densidade e telado vermelho foto conversora. O delineamento utilizado foi o de blocos casualizados com três repetições e dez cultivares (Amanda, Brida, Caipira, Camila, Cristal, Invicta, Solaris, Thais, Vanda e Vera). As variáveis analisadas foram: massa fresca total e comercial, massa fresca de caule e de raiz, número de folhas, comprimento e diâmetro de caule e teor de massa seca. A cultivar Brida, apresentou a maior massa fresca total (330,08 g planta-1) e comercial (308,50 g planta-1) no cultivo com cobertura de polietileno e também maior massa fresca total (341,2 g planta-1) e comercial (322,6 g planta-1) no cultivo em tela vermelha. Todas cultivares avaliadas, em ambos ambientes de cultivo, apresentaram tamanho para o mercado in natura.
... In lettuce, the great majority of transcriptomic studies related to anthocyanins are focused on the differences between green and red varieties (Moreno-Escamilla et al., 2020;Su et al., 2020). RNA-seq has also been used to study different abiotic stresses in this crop, e.g., high and low temperatures (Park et al., 2020;Chen et al., 2022a), the presence of heavy metals (Xiong et al., 2021), and even drought (Koyama et al., 2021). However, the specific effect of environmental factors on lettuce anthocyanin regulation has been scarcely studied, except in the case of different light conditions (Zhang et al., 2018;Wada et al., 2022). ...
Lettuce is a crop particularly vulnerable to drought. A transcriptomic study in the variety ‘Romired’ and the wild relative Lactuca homblei was conducted to understand the increase in anthocyanins (only significant in L. homblei) in response to drought previously observed. RNA-seq revealed more differentially expressed genes (DEGs), especially upregulated, in the wild species, in which the most abundant and significant GO terms were involved in regulatory processes (including response to water). Anthocyanin synthesis was triggered in L. homblei in response to drought, with 17 genes activated out of the 36 mapped in the phenylpropanoid-flavonoid pathway compared to 7 in ‘Romired’. Nineteen candidate DEGs with the strongest change in expression and correlation with both anthocyanin content and drought were selected and validated by qPCR, all being differentially expressed only in the wild species with the two techniques. Their functions were related to anthocyanins and/or stress response and they harboured 404 and 11 polymorphisms in the wild and cultivated species, respectively. Some wild variants had high or moderate predicted impacts on the respective protein function: a transcription factor that responds to abiotic stresses, a heat shock protein involved in stomatal closure, and a phospholipase participating in anthocyanin accumulation under abiotic stress. These genetic variants could explain the differences in the gene expression patterns between the wild (significantly up/downregulated) and the cultivated (no significant changes) species. The diversity of this crop wild relative for anthocyanin-related genes involved in the response to drought could be exploited to improve lettuce resilience against some adverse climate effects.
... For instance, tomato plants are highly sensitive to heat stress during flowering and fruit set stages, impacting yield and fruit quality [15,16]. Lettuce, typically a cool-season crop, is prone to bolting and altered taste of increased bitterness under high temperatures in the 32 -37°C range causing reduction in market value [17][18][19]. While little or no comprehensive research exists on the temperature responses of Mexican mint and industrial hemp, thermal stress can significantly alter the production of essential Mexican mint oil as well as the cannabinoid content and fiber quality of industrial hemp [20,21]. ...
Temperature stress is a major abiotic factor significantly impacting crop growth, development and productivity. In this study, we investigated the effects of different growth temperatures (10°C, 22°C, and 35°C) on the morphological, physiological and biochemical responses of five important crop species: green lettuce, hemp, mint, red lettuce and tomato. The results revealed that plant height and stem girth of tomato plants were not significantly (p > 0.05) altered under 22°C and 35°C, but were reduced by ca. 61.9% and 65.7% respectively under 10°C compared to 22°C. Green lettuce plants grown under 22°C had significantly (p < 0.001) higher total chlorophyll content of ca. 35.9% than those under 10°C. Mint plants exposed to extreme temperatures of 35°C and 10°C showed significant (p < 0.001) reductions of up to 19.7%, 60.2%, and 45.8% in chlorophyll fluorescence indices Fv/Fm, Fv/Fo, and total chlorophyll content, respectively, compared to those grown under 22°C. Malonaldehyde content (MDA) in mint and tomato plants increased by ca. 686.7% and 476.4%, respectively, under 10°C compared to 22°C, while in red lettuce, MDA content was reduced by ca. 136% under 10°C compared to 35°C. Notably, flavonoid accumulation was significantly higher in hemp plants compared to other species. The results suggest that crop species exhibit diverse responses to temperature stress, extending beyond morphological, physiological and biochemical adaptations. This diversity shows the differential adaptive strategies employed by various plant species in response to temperature stress conditions. The findings of this study can be explored by various crop improvement programs to enhance the tolerance of these crops to temperature extremes, thereby contributing to food security amidst the threats posed by climate change.
... AtMYB15 was reported to play an important role in inducing disease resistance through secondary cell wall formation [13]. LsMYB15 and BpMYB15 are also involved in heat stress resistance and flavonoid biosynthesis in lettuce and birch; therefore, they are potentially related to stress responses [44,45]. Moreover, OsMYB4 and ZmMYB39, which are closely related to PagMYB148, are involved in cold stress resistance in rice and maize, respectively [46,47]. ...
MYB transcription factors containing an R2R3 DNA-binding domain are involved in the regulation of various physiological processes, such as responses to abiotic stresses, including salt stress. In poplar, various MYB transcription factors regulate stress responses. In this study, we aimed to identify the correlation between the transcription factor MYB148 and salt stress responses in the hybrid poplar (Populus alba × P. glandulosa). We induced a mutation in the MYB-binding domain of PagMYB148 using CRISPR/Cas9-mediated editing of the PagMYB148 gene, which induced a more suppressed expression of PagMYB148 than that in the wild-type. Although salt and drought treatments enhance the expression of PagMYB148, the pagmyb148-transgenic plants exhibited more sensitive phenotypes than the wild-type plants under salt stress. After exposure to salinity stress, the chlorophyll content was lower in pagmyb148-transgenic plants than in wild-type plants, whereas the mutation increased ion leakage from cells. Additionally, the expression of genes involved in the salt stress response was higher in pagmyb148-transgenic plants than in the wild-type. After salt treatment, pagmyb148-transgenic plants exhibited an increased level of H2O2 and reduced activity of antioxidant enzymes. In summary, the MYB148 transcription factor is involved in the regulation of salt stress resistance in hybrid poplar trees. This report contributes to providing a basis for further investigating the molecular mechanisms of the poplar PagMYB148 transcription factor under abiotic stress.
... Its development and yield are greatly affected by heat stress. The lettuce plants are temperature-sensitive because the high temperatures would promote bolting while consumers are willing to purchase non-bolted lettuce in the market (Chen et al. 2022;Li et al. 2022). The biomass and morphology of lettuce reflected its yield and quality. ...
This study investigates the effects of selected PGPB on lettuce growth performance under heat-stress conditions. Bacterial plant growth-promoting potentials have been characterized and identified successfully in ongoing studies. Based on in vitro plant growth-promoting potential, the top five bacteria were ranked and identified as Acinetobacter sp. GRB12, Bacillus sp. GFB04, Klebsiella sp. LFB06, Klebsiella sp. GRB10, and Klebsiella sp. GRB04. They were mixed to inoculate on lettuce (Lactuca sativa L.) in temperature-controlled greenhouses. Another in-vivo chamber experiment was conducted by using Bacillus sp. GFB04 and Klebsiella sp. GFB10. Plant physiological traits (chlorophyll fluorescence and transpiration) and nutrient contents were measured at harvest, along with growth, development, and yield component analyses. Uninoculated plants under heat-stress condition showed poor growth performance. In contrast, plants with PGPB inoculation showed improved growth under heat-stress conditions, as the uptake of nutrients was facilitated by the symbionts. Inoculation also improved lettuce photosystem II efficiency and decreased total water use under heat stress. In conclusion, the current study suggests that PGPB inoculation successfully enhances lettuce heat-tolerance. PGPB application could potentially help improve sustainable production of lettuce with less fertilization under increasing temperatures.
... Lettuce (Lactuca sativa L.) is a primary vegetable cultivated in fields or facilities, valued for its significant culinary and economic importance [1,2]. Unfortunately, during cultivation, it is susceptible to various abiotic and biotic stresses, including high salinity, drought, extreme temperatures (both high and low), and pathogen infections [3,4]. Particularly, it is prone to bolting under the influence of high temperatures, a process that limits the marketability of lettuce [5]. ...
... Exogenous melatonin was applied every 3 days, and the plants were sampled at around 9 am after 30 days of high-temperature treatment. We selected leaves on days 0, 6,9,15,18, and 27 (in triplicate), measured the physiological parameters of the leaves, and conducted RNA-seq analysis [4]. By analyzing the transcriptome data, we identified transcriptional changes associated with the LsGRAS genes under these conditions. ...
... The identified recombinant plasmid was then transformed into Agrobacterium GV3101, and the infection solution was prepared. The infection buffer comprised 10 mM magnesium chloride, 10 mM MES buffer, and 20 mM acetylsyringone (MMA) [4]. The experiment was categorized into three groups: a blank control group (WT), a negative control group (TRV2-TRV1), and an experimental group (TRV2-LsGRAS13). ...
Lettuce is susceptible to high-temperature stress during cultivation, leading to bolting and affecting yield. Plant-specific transcription factors, known as GRAS proteins, play a crucial role in regulating plant growth, development, and abiotic stress responses. In this study, the entire lettuce LsGRAS gene family was identified. The results show that 59 LsGRAS genes are unevenly distributed across the nine chromosomes. Additionally, all LsGRAS proteins showed 100% nuclear localization based on the predicted subcellular localization and were phylogenetically classified into nine conserved subfamilies. To investigate the expression profiles of these genes in lettuce, we analyzed the transcription levels of all 59 LsGRAS genes in the publicly available RNA-seq data under the high-temperature treatment conducted in the presence of exogenous melatonin. The findings indicate that the transcript levels of the LsGRAS13 gene were higher on days 6, 9, 15, 18, and 27 under the high-temperature (35/30 °C) treatment with melatonin than on the same treatment days without melatonin. The functional studies demonstrate that silencing LsGRAS13 accelerated bolting in lettuce. Furthermore, the paraffin sectioning results showed that flower bud differentiation in LsGRAS13-silenced plants occurred significantly faster than in control plants. In this study, the LsGRAS genes were annotated and analyzed, and the expression pattern of the LsGRAS gene following melatonin treatment under high-temperature conditions was explored. This exploration provides valuable information and identifies candidate genes associated with the response mechanism of lettuce plants high-temperature stress.
... Our findings indicate a significant accumulation of ABA in EBF plants, suggesting its potential role as a key metabolite in such plants. Furthermore, the expression patterns of ABA-related genes exhibited a positive correlation with stem length during the development of leaf lettuce, consistent with the outcomes of the investigation [31]. All evidence indicated that studying the changes in differential metabolites in EBF plants was necessary. ...
The root of Angelica sinensis is utilized in Traditional Chinese medicine to enhance blood replenishment and facilitate blood circulation. The early bolting and flowering (EBF) of A. sinensis, however, compromises the quality of the roots and restricts the yield of medicinal substances. The study was conducted to compare the transcriptomic and metabolomic profiles between EBF plants and normal plants of two cultivars of A. sinensis, followed by validation of the transcriptome results using qRT-PCR. There were 3677 DEGs in EBF plants compared to normal plants of cultivar 2 (Mingui No.2), and cultivar 4 (Mingui No.4) was 3354. The main differential metabolites in the EBF and normal plants were phenolic acids, flavonoids, lignans, and coumarins. The analysis of 5 EBF-related pathways revealed 28 genes exhibiting differential expression and 5 metabolites showing differential accumulation. The expression of the Lhcb5, Lhcb2, Lhcb6, Lhcb1, Lhca4, ATPG1, EGLC, CELB, AMY, glgA, CYCD3, SnRK2, PYL, AHK2, AUX1, BSK, FabI/K, ACACA and FabV decreased and the expression of the PsbR, PsbA, LHY, FT, CO, malQ, HK, GPI and DELLA increased in EBF plants. In addition, the Abscisic acid, d-Glucose-6P, α-d-Glucose-1P, NADP+, and ADP were more significantly enriched in EBF plants. The findings offer novel perspectives on the EBF mechanisms in A. sinensis and other medicinal plants of the Apiaceae family.
... These stresses have led to severe declines in harvest indices in many regions of the world and have limited their geographical distribution [7,8] . Thus, delayed bolting and owering are preferred for lettuce to maximize harvestable yield while maintaining cooking quality [9] . Plants as sessile organisms evolved different strategies to regulate their physiology in response to uctuating environmental conditions [10] . ...
... To investigate the expression pro les of 59 LsGRAS members in lettuce under exogenous melatonin, we downloaded publicly available leaf transcriptome data from NCBI (Bio project PRJNA810911) [9] and conducted RNA-Seq analysis. The results showed that the changing pattern of the LsGRAS13 gene was consistent. ...
... Transcriptome data of the LsGRAS genes in leaves and under high-temperature stress in lettuce were obtained from our previous study [9] . To be speci c the lettuce plant was treated with exogenous melatonin for 100 µmol L − 1 melatonin, with the control 0 µmol L − 1 melatonin, while high-temperature stress was also applied to the plant. ...
Lettuce is one of the most popular leafy vegetables in the world, but it is prone to high-temperature stress in the cultivation process leading to bolting, which affects the yield. The plant-specific transcription factors, GRAS proteins, play an important role which regulates plant growth development and abiotic stress. However, there is no comprehensive study of the GRAS gene family in lettuce. In this study, the complete LsGRAS genome was identified its expression was analyzed. The results showed that the 59 LsGRAS genes were classified phylogenetically divided into 4 conserved subfamilies and distributed unevenly on 9 chromosomes, with 50% physically adjacent to at least one another and 100% localized on the nucleus. Chromosome localization and gene structure analysis suggested that duplication events and a large number presence of intronless genes might be the reason why the LsGRAS gene family expands massively. Combined with gene annotation and interaction network analysis, the expression pattern of the LsGRAS gene under high-temperature treatment was analyzed, revealing the potential different functions of the LsGRAS gene under high-temperature stress. In conclusion, this study provides valuable information and candidate genes for improving the ability of lettuce to tolerate high-temperature stress.
... In this sense, lettuce wild relatives, e.g., Lactuca serriola L., have been used to explore the differential expression of candidate genes responsible for the synthesis of antioxidant compounds [7,9]. Transcriptomic studies to evaluate the response to different abiotic stresses, e.g., cold [10], heat [11,12], heavy metals [13,14], drought [15,16] and UV radiation [17] have been performed in lettuce. However, before this work, anthocyanin regulation has not been studied either under drought stress or in different tissues in the genus Lactuca. ...
Lettuce is a popular vegetable source of bioactive compounds, like anthocyanins, powerful antioxidants present in red and semi-red varieties. Selection of reliable reference genes (RGs) for the normalization of real-time quantitative PCR (qPCR) data is crucial to obtain accurate gene expression results. Among the genes with totally unrelated biological functions, six candidate RGs (ADF2, CYB5, iPGAM, SCL13, TRXL3-3, and VHA-H) with low variation in expression according to RNA-seq analyses, were selected for future expression studies of anthocyanin-related genes in three different experiments: leaf colour comparison (green vs. red) in commercial varieties; tissue comparison (leaf vs. stem) in a wild relative; and drought stress experiment in commercial and traditional varieties, and a wild relative. Expression profiles of the candidate RGs were obtained by qPCR and their stability was assessed by four different analytical tools, geNorm, NormFinder, BestKeeper, and Delta Ct method, all integrated in RefFinder. All results considered, we recommend CYB5 to be used as RG for the leaf colour experiment and TRXL3-3 for the tissue and drought stress ones, as they were the most stable genes in each case. RNA-seq is useful to preselect novel RGs although validation by qPCR is still advisable. These results provide helpful information for gene expression studies in Lactuca spp. under the described conditions.
