ABSTRACT
This study evaluated the foliar antioxidant activity in nine Hevea brasiliensis genotypes from the ECC-1 (Élite Caquetá Colombia) selection and IAN 873 cultivar (control) in trees in the growth stage in two large-scale clonal trials in response to different climatic (semi-humid warm and humid warm sites) and seasonal (dry and rainy periods) conditions in the Colombian Amazon. The results indicated that Reactive Oxygen Species (ROS) production increased under conditions of lower water availability (dry period), leading to lipid peroxidation, high defense of photosynthetic pigments, and development of better osmotic adjustment capacity in the ECC 64, IAN 873, ECC 90, and ECC 35 genotypes due to high concentrations of carotenoids (0.40 mg g-1), reducing sugars (65.83 µg mg-1), and malondialdehyde (MDA) (2.44 nmol ml-1). In contrast, during the rainy period, a post-stress action was observed due to high contents of proline and total sugars (39.43 µg g-1 and 173.03 µg g-1, respectively). At the site level, with high Photosynthetically Active Radiation (PAR) values (1143 moles photons m-2 s-1), temperature (32.11°C), and lower precipitation (135 mm), higher antioxidant activity (chlorophylls a, b and total, carotenoids, and proline) was recorded at the humid warm site, demonstrating that the ECC 90, ECC 64, and ECC 66 genotypes are tolerant to water deficit compared to IAN 873. The ECC 64 genotype, independent of seasonal changes and site conditions, presented the highest contents in Chl a, total Chl, reducing sugars, total sugars, and MDA, showing a tendency to adapt to fluctuating conditions. This study showed that water fluctuations do not cause the same metabolic responses, these vary within the same species, depending on their developmental stage and the climatic and seasonal variations characteristic of the Colombian Amazon.
Subject(s)
Antioxidants , Genotype , Hevea , Plant Leaves , Water , Antioxidants/metabolism , Colombia , Plant Leaves/genetics , Plant Leaves/metabolism , Water/metabolism , Hevea/genetics , Hevea/metabolism , Photosynthesis/genetics , Plant Breeding/methods , Carotenoids/metabolism , Reactive Oxygen Species/metabolism , Malondialdehyde/metabolism , Lipid Peroxidation , SeasonsABSTRACT
Oil palm (Elaeis guineensis Jacq.) is a highly productive crop economically significant for food, cosmetics, and biofuels. Abiotic stresses such as low water availability, salt accumulation, and high temperatures severely impact oil palm growth, physiology, and yield by restricting water flux among soil, plants, and the environment. While drought stress's physiological and biochemical effects on oil palm have been extensively studied, the molecular mechanisms underlying drought stress tolerance remain unclear. Under water deficit conditions, this study investigates two commercial E. guineensis cultivars, IRHO 7001 and IRHO 2501. Water deficit adversely affected the physiology of both cultivars, with IRHO 2501 being more severely impacted. After several days of water deficit, there was a 40% reduction in photosynthetic rate (A) for IRHO 7001 and a 58% decrease in IRHO 2501. Further into the drought conditions, there was a 75% reduction in A for IRHO 7001 and a 91% drop in IRHO 2501. Both cultivars reacted to the drought stress conditions by closing stomata and reducing the transpiration rate. Despite these differences, no significant variations were observed between the cultivars in stomatal conductance, transpiration, or instantaneous leaf-level water use efficiency. This indicates that IRHO 7001 is more tolerant to drought stress than IRHO 2501. A differential gene expression and network analysis was conducted to elucidate the differential responses of the cultivars. The DESeq2 algorithm identified 502 differentially expressed genes (DEGs). The gene coexpression network for IRHO 7001 comprised 274 DEGs and 46 predicted HUB genes, whereas IRHO 2501's network included 249 DEGs and 3 HUB genes. RT-qPCR validation of 15 DEGs confirmed the RNA-Seq data. The transcriptomic profiles and gene coexpression network analysis revealed a set of DEGs and HUB genes associated with regulatory and transcriptional functions. Notably, the zinc finger protein ZAT11 and linoleate 13S-lipoxygenase 2-1 (LOX2.1) were overexpressed in IRHO 2501 but under-expressed in IRHO 7001. Additionally, phytohormone crosstalk was identified as a central component in the response and adaptation of oil palm to drought stress.
Subject(s)
Arecaceae , Droughts , Gene Expression Regulation, Plant , Stress, Physiological , Transcriptome , Stress, Physiological/genetics , Arecaceae/genetics , Arecaceae/physiology , Arecaceae/metabolism , Gene Expression Profiling , Photosynthesis/genetics , Plant Proteins/genetics , Plant Proteins/metabolismABSTRACT
Advancing chloroplast genetic engineering in Chlamydomonas reinhardtii remains challenging, decades after its first successful transformation. This study introduces the development of a chloroplast-optimized mNeonGreen fluorescent reporter, enabling in vivo observation through a sixfold increase in fluorescence via context-aware construct engineering. Our research highlights the influence of transcriptional readthrough and antisense mRNA pairing on post-transcriptional regulation, pointing to novel strategies for optimizing heterologous gene expression. We further demonstrate the applicability of these insights using an accessible experimentation system using glass-bead transformation and reestablishment of photosynthesis using psbH mutants, focusing on the mitigation of transcriptional readthrough effects. By characterizing heterologous expression using regulatory elements such as PrrnS, 5'atpA, and 3' rbcL in a sense-transcriptional context, we further documented up to twofold improvement in fluorescence levels. Our findings contribute new tools for molecular biology research in the chloroplast and evidence fundamental gene regulation processes that could enable the development of more effective chloroplast engineering strategies. This work not only paves the way for more efficient genetic engineering of chloroplasts but also deepens our understanding of the regulatory mechanisms at play.
Subject(s)
Chlamydomonas reinhardtii , Chloroplasts , Chlamydomonas reinhardtii/genetics , Chlamydomonas reinhardtii/metabolism , Chloroplasts/metabolism , Chloroplasts/genetics , Gene Expression Regulation, Plant , Transcription, Genetic , Genes, Reporter , Photosynthesis/genetics , RNA, Antisense/genetics , Luminescent Proteins/genetics , Luminescent Proteins/metabolismABSTRACT
MAIN CONCLUSIONS: In contrast to Neltuma species, S. tamarugo exhibited higher stress tolerance, maintaining photosynthetic performance through enhanced gene expression and metabolites. Differentially accumulated metabolites include chlorophyll and carotenoids and accumulation of non-nitrogen osmoprotectants. Plant species have developed different adaptive strategies to live under extreme environmental conditions. Hypothetically, extremophyte species present a unique configuration of physiological functions that prioritize stress-tolerance mechanisms while carefully managing resource allocation for photosynthesis. This could be particularly challenging under a multi-stress environment, where the synthesis of multiple and sequential molecular mechanisms is induced. We explored this hypothesis in three phylogenetically related woody species co-occurring in the Atacama Desert, Strombocarpa tamarugo, Neltuma alba, and Neltuma chilensis, by analyzing their leaf dehydration and freezing tolerance and by characterizing their photosynthetic performance under natural growth conditions. Besides, the transcriptomic profiling, biochemical analyses of leaf pigments, and metabolite analysis by untargeted metabolomics were conducted to study gene expression and metabolomic landscape within this challenging multi-stress environment. S. tamarugo showed a higher photosynthetic capacity and leaf stress tolerance than the other species. In this species, a multifactorial response was observed, which involves high photochemical activity associated with a higher content of chlorophylls and ß-carotene. The oxidative damage of the photosynthetic apparatus is probably attenuated by the synthesis of complex antioxidant molecules in the three species, but S. tamarugo showed the highest antioxidant capacity. Comparative transcriptomic and metabolomic analyses among the species showed the differential expression of genes involved in the biosynthetic pathways of key stress-related metabolites. Moreover, the synthesis of non-nitrogen osmoprotectant molecules, such as ciceritol and mannitol in S. tamarugo, would allow the nitrogen allocation to support its high photosynthetic capacity without compromising leaf dehydration tolerance and freezing stress avoidance.
Subject(s)
Desert Climate , Photosynthesis , Stress, Physiological , Transcriptome , Photosynthesis/genetics , Stress, Physiological/genetics , Chlorophyll/metabolism , Metabolomics , Plant Leaves/metabolism , Plant Leaves/genetics , Plant Leaves/physiology , Gene Expression Regulation, Plant , Gene Expression Profiling , Carotenoids/metabolism , Metabolome/genetics , ChileABSTRACT
The GOLDEN2-LIKE (GLK) transcription factors act as a central regulatory node involved in both developmental processes and environmental responses. Marchantia polymorpha, a basal terrestrial plant with strategic evolutionary position, contains a single GLK representative that possesses an additional domain compared to spermatophytes. We analyzed the role of MpGLK in chloroplast biogenesis and development by altering its levels, preforming transcriptomic profiling and conducting chromatin immunoprecipitation. Decreased MpGLK levels impair chloroplast differentiation and disrupt the expression of photosynthesis-associated nuclear genes, while overexpressing MpGLK leads to ectopic chloroplast biogenesis. This demonstrates the MpGLK functions as a bona fide GLK protein, likely representing an ancestral GLK architecture. Altering MpGLK levels directly regulates the expression of genes involved in Chl synthesis and degradation, similar to processes observed in eudicots, and causes various developmental defects in Marchantia, including the formation of dorsal structures such as air pores and gemma cups. MpGLK, also directly activates MpMAX2 gene expression, regulating the timing of gemma cup development. Our study shows that MpGLK functions as a master regulator, potentially coupling chloroplast development with vegetative reproduction. This illustrates the complex regulatory networks governing chloroplast function and plant development communication and highlight the evolutionary conservation of GLK-mediated regulatory processes across plant species.
Subject(s)
Chloroplasts , Gene Expression Regulation, Plant , Marchantia , Plant Proteins , Transcription Factors , Marchantia/genetics , Marchantia/growth & development , Marchantia/metabolism , Chloroplasts/metabolism , Chloroplasts/genetics , Transcription Factors/metabolism , Transcription Factors/genetics , Plant Proteins/metabolism , Plant Proteins/genetics , Plant Development/genetics , Photosynthesis/geneticsABSTRACT
Microalgae's ability to mitigate flue gas is an attractive technology that can valorize gas components through biomass conversion. However, tolerance and growth must be ideal; therefore, acclimation strategies are suggested. Here, we compared the transcriptome and lipidome of Desmodesmus abundans strains acclimated to high CO2 (HCA) and low CO2 (LCA) under continuous supply of model flue gas (MFG) and incomplete culture medium (BG11-N-S). Initial growth and nitrogen consumption from MFG were superior in strain HCA, reaching maximum productivity a day before strain LCA. However, similar productivities were attained at the end of the run, probably because maximum photobioreactor capacity was reached. RNA-seq analysis during exponential growth resulted in 16,435 up-regulated and 4,219 down-regulated contigs in strain HCA compared to LCA. Most differentially expressed genes (DEGs) were related to nucleotides, amino acids, C fixation, central carbon metabolism, and proton pumps. In all pathways, a higher number of up-regulated contigs with a greater magnitude of change were observed in strain HCA. Also, cellular component GO terms of chloroplast and photosystems, N transporters, and secondary metabolic pathways of interest, such as starch and triacylglycerols (TG), exhibited this pattern. RT-qPCR confirmed N transporters expression. Lipidome analysis showed increased glycerophospholipids in strain HCA, while LCA exhibited glycerolipids. Cell structure and biomass composition also revealed strains differences. HCA possessed a thicker cell wall and presented a higher content of pigments, while LCA accumulated starch and lipids, validating transcriptome and lipidome data. Overall, results showed significant differences between strains, where characteristic features of adaptation and tolerance to high CO2 might be related to the capacity to maintain a higher flux of internal C, regulate intracellular acidification, active N transporters, and synthesis of essential macromolecules for photosynthetic growth.
Subject(s)
Acclimatization , Carbon Dioxide , Lipidomics , Transcriptome , Carbon Dioxide/metabolism , Acclimatization/genetics , Lipidomics/methods , Microalgae/genetics , Microalgae/metabolism , Microalgae/growth & development , Gene Expression Profiling , Photosynthesis/genetics , Lipid Metabolism/genetics , Chlorophyceae/genetics , Chlorophyceae/metabolismABSTRACT
To analyze the effect of oligo-carrageenan (OC) kappa in the stimulation of growth in Arabidopsis thaliana, plants were sprayed on leaves with an aqueous solution of OC kappa at 1 mg mL-1, 5 times every 2 days and cultivated for 5 or 15 additional days. Plants treated with OC kappa showed an increase in rosette diameter, fresh and dry weight, and primary root length. Plants treated with OC kappa once and cultivated for 0 to 24 h after treatment were subjected to transcriptomic analyses to identify differentially expressed genes, mainly at 12 h after treatment. Transcripts encoding proteins involved in growth and development and photosynthesis were upregulated as well as enzymes involved in primary metabolism. In addition, plants treated with OC kappa once and cultivated for 0 to 96 h showed increased levels of transcripts encoding enzymes involved in C, N, and S assimilation at 6 and 12 h after treatment that remain increased until 96 h. Therefore, OC kappa increased the expression of genes encoding proteins involved in photosynthesis, C, N, and S assimilation, and growth in A. thaliana.
Subject(s)
Arabidopsis Proteins , Arabidopsis , Arabidopsis/metabolism , Carrageenan/pharmacology , Photosynthesis/genetics , Plants/metabolism , Gene Expression Profiling , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Gene Expression Regulation, PlantABSTRACT
Warming in the Antarctic Peninsula is one of the fastest on earth, and is predicted to become more asymmetric in the near future. Warming has already favored the growth and reproduction of Antarctic plant species, leading to a decrease in their freezing tolerance (deacclimation). Evidence regarding the effects of diurnal and nocturnal warming on freezing tolerance-related gene expression in D. antarctica is negligible. We hypothesized that freezing tolerance-related gene (such as CBF-regulon) expression is reduced mainly by nocturnal warming rather than diurnal temperature changes in D. antarctica. The present work aimed to determine the effects of diurnal and nocturnal warming on cold deacclimation and its associated gene expression in D. antarctica, under laboratory conditions. Fully cold-acclimated plants (8 °C/0 °C), with 16h/8h thermoperiod and photoperiod duration, were assigned to four treatments for 14 days: one control (8 °C/0 °C) and three with different warming conditions (diurnal (14 °C/0 °C), nocturnal (8 °C/6 °C), and diurnal-nocturnal (14 °C/6 °C). RNA-seq was performed and differential gene expression was analyzed. Nocturnal warming significantly down-regulated the CBF transcription factors expression and associated cold stress response genes and up-regulated photosynthetic and growth promotion genes. Consequently, nocturnal warming has a greater effect than diurnal warming on the cold deacclimation process in D. antarctica. The eco-physiological implications are discussed.
Subject(s)
Acclimatization , Cold Temperature , Acclimatization/genetics , Transcription Factors/metabolism , Photosynthesis/genetics , Gene Expression ProfilingABSTRACT
BACKGROUND: C4 photosynthesis is a mechanism that plants have evolved to reduce the rate of photorespiration during the carbon fixation process. The C4 pathway allows plants to adapt to high temperatures and light while more efficiently using resources, such as water and nitrogen. Despite decades of studies, the evolution of the C4 pathway from a C3 ancestor remains a biological enigma. Interestingly, species with C3-C4 intermediates photosynthesis are usually found closely related to the C4 lineages. Indeed, current models indicate that the assembly of C4 photosynthesis was a gradual process that included the relocalization of photorespiratory enzymes, and the establishment of intermediate photosynthesis subtypes. More than a third of the C4 origins occurred within the grass family (Poaceae). In particular, the Otachyriinae subtribe (Paspaleae tribe) includes 35 American species from C3, C4, and intermediates taxa making it an interesting lineage to answer questions about the evolution of photosynthesis. RESULTS: To explore the molecular mechanisms that underpin the evolution of C4 photosynthesis, the transcriptomic dynamics along four different leaf segments, that capture different stages of development, were compared among Otachyriinae non-model species. For this, leaf transcriptomes were sequenced, de novo assembled, and annotated. Gene expression patterns of key pathways along the leaf segments showed distinct differences between photosynthetic subtypes. In addition, genes associated with photorespiration and the C4 cycle were differentially expressed between C4 and C3 species, but their expression patterns were well preserved throughout leaf development. CONCLUSIONS: New, high-confidence, protein-coding leaf transcriptomes were generated using high-throughput short-read sequencing. These transcriptomes expand what is currently known about gene expression in leaves of non-model grass species. We found conserved expression patterns of C4 cycle and photorespiratory genes among C3, intermediate, and C4 species, suggesting a prerequisite for the evolution of C4 photosynthesis. This dataset represents a valuable contribution to the existing genomic resources and provides new tools for future investigation of photosynthesis evolution.
Subject(s)
Biological Evolution , Poaceae , Poaceae/genetics , Transcriptome , Photosynthesis/genetics , Plants/genetics , Plant Leaves/genetics , Plant Leaves/metabolismABSTRACT
A momentary increase in cytoplasmic Ca2+ generates an oscillation responsible for the activation of proteins, such as calmodulin and kinases, which interact with reactive oxygen species (ROS) for the transmission of a stress signal. This study investigated the influence of variations in calcium concentrations on plant defense signaling and photosynthetic acclimatization after mechanical damage. Solanum lycopersicum Micro-Tom was grown with 0, 2 and 4 mM Ca2+, with and without mechanical damage. The expression of stress genes was evaluated, along with levels of antioxidant enzymes, hydrogen peroxide, lipid peroxidation, histochemistry, photosynthesis and dry mass of organs. The ROS production generated by mechanical damage was further enhanced by calcium-free conditions due to the inactivation of the oxygen evolution complex, contributing to an increase in reactive species. The results indicated that ROS affected mechanical damage signaling because calcium-free plants exhibited high levels of H2O2 and enhanced expression of kinase and RBOH1 genes, necessary conditions for an efficient response to stress. We conclude that the plants without calcium supply recognized mechanical damage but did not survive. The highest expression of the RBOH1 gene and the accumulation of H2O2 in these plants signaled cell death. Plants grown in the presence of calcium showed higher expression of SlCaM2 and control of H2O2 concentration, thus overcoming the stress caused by mechanical damage, with photosynthetic acclimatization and without damage to dry mass production.
Subject(s)
Solanum lycopersicum , Solanum lycopersicum/metabolism , Hydrogen Peroxide/metabolism , Reactive Oxygen Species/metabolism , Calcium Signaling , Photosynthesis/genetics , Acclimatization , Antioxidants/metabolism , Gene Expression , Plant Leaves/metabolismABSTRACT
KEY MESSAGE: High pigment mutants in tomato (Solanum lycopersicum L.), a loss of function in the control of photomorphogenesis, with greater pigment production, show altered growth, greater photosynthesis, and a metabolic reprogramming. High pigment mutations cause plants to be extremely responsive to light and produce excessive pigmentation as well as fruits with high levels of health-beneficial nutrients. However, the association of these traits with changes in the physiology and metabolism of leaves remains poorly understood. Here, we performed a detailed morphophysiological and metabolic characterization of high pigment 1 (hp1) and high pigment 2 (hp2) mutants in tomato (Solanum lycopersicum L. 'Micro-Tom') plants under different sunlight conditions (natural light, 50% shading, and 80% shading). These mutants occur in the DDB1 (hp1) and DET1 (hp2) genes, which are related to the regulation of photomorphogenesis and chloroplast development. Our results demonstrate that these mutations delay plant growth and height, by affecting physiological and metabolic parameters at all stages of plant development. Although the mutants were characterized by higher net CO2 assimilation, lower stomatal limitation, and higher carboxylation rates, with anatomical changes that favour photosynthesis, we found that carbohydrate levels did not increase, indicating a change in the energy flow. Shading minimized the differences between mutants and the wild type or fully reversed them in the phenotype at the metabolic level. Our results indicate that the high levels of pigments in hp1 and hp2 mutants represent an additional energy cost for these plants and that extensive physiological and metabolic reprogramming occurs to support increased pigment biosynthesis.
Subject(s)
Solanum lycopersicum , Carbon/metabolism , Chromosomal Proteins, Non-Histone/metabolism , Solanum lycopersicum/metabolism , Photosynthesis/genetics , Pigmentation/genetics , Plant Leaves/metabolism , Plant Proteins/genetics , Plants/metabolismABSTRACT
Heterobaric leaves have bundle sheath extensions (BSEs) that compartmentalize the parenchyma, whereas homobaric leaves do not. The presence of BSEs affects leaf hydraulics and photosynthetic rate. The tomato (Solanum lycopersicum) obscuravenosa (obv) mutant lacks BSEs. Here, we identify the obv gene and the causative mutation, a nonsynonymous amino acid change that disrupts a C2H2 zinc finger motif in a putative transcription factor. This mutation exists as a polymorphism in the natural range of wild tomatoes but has increased in frequency in domesticated tomatoes, suggesting that the latter diversified into heterobaric and homobaric leaf types. The obv mutant displays reduced vein density, leaf hydraulic conductance and photosynthetic assimilation rate. We show that these and other pleiotropic effects on plant development, including changes in leaf insertion angle, leaf margin serration, minor vein density, and fruit shape, are controlled by OBV via changes in auxin signaling. Loss of function of the transcriptional regulator AUXIN RESPONSE FACTOR 4 (ARF4) also results in defective BSE development, revealing an additional component of a genetic module controlling aspects of leaf development important for ecological adaptation and subject to breeding selection.
Subject(s)
Solanum lycopersicum , Indoleacetic Acids/metabolism , Solanum lycopersicum/metabolism , Photosynthesis/genetics , Plant Breeding , Plant Leaves/metabolism , Plant Proteins/metabolismABSTRACT
Wheat crop is very sensitive to osmotic stress conditions. As an abiotic stress, drought may exert a considerable effect on the levels of specialized metabolites in plants. These metabolites may exert beneficial biological activities in the prevention or treatment of disorders linked to oxidative stress in plants and humans. Furthermore, osmoprotector accumulation helps wheat to increase the maintenance of osmotic balance. Therefore, identifying wheat genotypes with better drought tolerance is extremely important. In this sense, this research aimed to understand agronomic, physiological and biochemical responses of spring wheat strains and cultivars to drought stress, under field conditions, and jointly select strains via multi-trait index. We evaluated agronomic, physiological and biochemical variables in 18 genotypes under field condition. The results demonstrated that all variables were affected by the drought. Most genotypes were significantly reduced in grain yield, except VI_14774, VI_14668, VI_9007 and TBIO_ATON. The variables related to photosynthesis were also affected. An increase above 800% was observed in proline contents in genotypes under drought. Sodium and potassium also increased, mainly for VI_131313 (Na), while VI_130758 and VI_14774 presented increased K. We evaluated the antioxidant potential of the different strains and the total content of phenolic compounds. The most drought-responsive genotypes were BRS_264, VI_14050 and VI_14426. Reduced grain yield and photosynthetic variables, and increased specialized metabolism compounds are due to plant defense mechanisms against drought conditions. Furthermore, variation in genotypes can be explained by the fact that each plant presents a different defense and tolerance mechanism, which may also occur between genotypes of the same species. Four strains were selected by the multivariate index: VI_14055, VI_14001, VI_14426 and VI_1466. Such results allow us to predict which genotype(s) performed best in semi-arid environments and under climatic fluctuations.
Subject(s)
Droughts , Triticum , Antioxidants/metabolism , Genotype , Humans , Photosynthesis/genetics , Stress, Physiological/genetics , Triticum/metabolismABSTRACT
Botryococcus braunii produce liquid hydrocarbons able to be processed into combustion engine fuels. Depending on the growing conditions, the cell doubling time can be up to 6 days or more, which is a slow growth rate in comparison with other microalgae. Few studies have analyzed the cell cycle of B. braunii. We did a bioinformatic comparison between the protein sequences for retinoblastoma and cyclin-dependent kinases from the A (Yamanaka) and B (Showa) races, with those sequences from other algae and Arabidopsis thaliana. Differences in the number of cyclin-dependent kinases and potential retinoblastoma phosphorylation sites between the A and B races were found. Some cyclin-dependent kinases from both races seemed to be phylogenetically more similar to A. thaliana than to other microalgae. Microscopic observations were done using several staining procedures. Race A colonies, but not race B, showed some multinucleated cells without chlorophyll. An active mitochondrial net was detected in those multinucleated cells, as well as being defined in polyphosphate bodies. These observations suggest differences in the cell division processes between the A and B races of B. braunii.
Subject(s)
Amino Acid Sequence/genetics , Cell Division/genetics , Hydrocarbons/metabolism , Microalgae/genetics , Arabidopsis/genetics , Cell Cycle/genetics , Cell Lineage/genetics , Chlorophyll/genetics , Computer Simulation , Hydrocarbons/chemistry , Microalgae/growth & development , Photosynthesis/geneticsABSTRACT
Cultivated tomato Solanum lycopersicum (Slyc) is sensitive to water shortages, while its wild relative Solanum peruvianum L. (Sper), an herbaceous perennial small shrub, can grow under water scarcity and soil salinity environments. Plastic Sper modifies the plant architecture when suffering from drought, which is mediated by the replacement of leaf organs, among other changes. The early events that trigger acclimation and improve these morphological traits are unknown. In this study, a physiological and transcriptomic approach was used to understand the processes that differentiate the response in Slyc and Sper in the context of acclimation to stress and future consequences for plant architecture. In this regard, moderate (MD) and severe drought (SD) were imposed, mediating PEG treatments. The results showed a reduction in water and osmotic potential during stress, which correlated with the upregulation of sugar and proline metabolism-related genes. Additionally, the senescence-related genes FTSH6 protease and asparagine synthase were highly induced in both species. However, GO categories such as "protein ubiquitination" or "endopeptidase inhibitor activity" were differentially enriched in Sper and Slyc, respectively. Genes related to polyamine biosynthesis were induced, while several cyclins and kinetin were downregulated in Sper under drought treatments. Repression of photosynthesis-related genes was correlated with a higher reduction in the electron transport rate in Slyc than in Sper. Additionally, transcription factors from the ERF, WRKY and NAC families were commonly induced in Sper. Although some similar responses were induced in both species under drought stress, many important changes were detected to be differentially induced. This suggests that different pathways dictate the strategies to address the early response to drought and the consequent episodes in the acclimation process in both tomato species.
Subject(s)
Acclimatization/genetics , Solanum lycopersicum/genetics , Stress, Physiological/genetics , Acclimatization/physiology , Droughts , Gene Expression/genetics , Gene Expression Profiling/methods , Gene Expression Regulation, Plant/genetics , Solanum lycopersicum/metabolism , Osmosis/physiology , Photosynthesis/genetics , Plant Leaves/metabolism , Plant Proteins/genetics , Salinity , Solanum/genetics , Solanum/metabolism , Transcription Factors/genetics , Transcriptome/geneticsABSTRACT
The aim of this study was to identify the correlation between photochemical efficiency and candidate genes expression to elucidate the drought tolerance mechanisms in coffee progenies (Icatu Vermelho IAC 3851-2 × Catimor UFV 1602-215) previously identified as tolerant in field conditions. Four progenies (2, 5, 12 and 15) were evaluated under water-deficit conditions (water deficit imposed 8 months after transplanting seedlings to the pots) and under irrigated system. Evaluations of physiological parameters and expression of candidate genes for drought tolerance were performed. Progeny 5 showed capacity to maintain water potential, which contributed to lower qP variation between irrigated and deficit conditions. However, the increases of qN and NPQ in response to stress indicate that this progeny is photochemically responsive to small variations of Ψam protecting the photosystem and maintaining qP. Data obtained for progeny 12 indicated a lower water status maintenance capacity, but with increased qN and NPQ providing maintenance of the ɸPSII and ETR parameters. A PCA analysis revealed that the genes coding regulatory proteins, ABA-synthesis, cellular protectors, isoforms of ascorbate peroxidase clearly displayed a major response to drought stress and discriminated the progenies 5 and 12 which showed a better photochemical response. The genes CaMYB1, CaERF017, CaEDR2, CaNCED, CaAPX1, CaAPX5, CaGolS3, CaDHN1 and CaPYL8a were up-regulated in the arabica coffee progenies with greater photochemical efficiency under deficit and therefore contributing to efficiency of the photosynthesis in drought tolerant progenies.
Subject(s)
Coffea/physiology , Droughts , Gene Expression Regulation, Plant , Photosynthesis/genetics , Stress, Physiological/genetics , Adaptation, Biological , Gene Expression Profiling , Plant Physiological Phenomena , Time FactorsABSTRACT
The C4 crop maize (Zea mays) is the most widely grown cereal crop worldwide and is an essential feedstock for food and bioenergy. Improving maize yield is important to achieve food security and agricultural sustainability in the 21st century. One potential means to improve crop productivity is to enhance photosynthesis. ictB, a membrane protein that is highly conserved across cyanobacteria, has been shown to improve photosynthesis, and often biomass, when introduced into diverse C3 plant species. Here, ictB from Synechococcus sp. strain PCC 7942 was inserted into maize using Agrobacterium-mediated transformation. In three controlled-environment experiments, ictB insertion increased leaf starch and sucrose content by up to 25% relative to controls. Experimental field trials in four growing seasons, spanning the Midwestern United States (Summers 2018 & 2019) and Argentina (Winter 2018 & 2019), showed an average of 3.49% grain yield improvement, by as much as 5.4% in a given season and up to 9.4% at certain trial locations. A subset of field trial locations was used to test for modification of ear traits and ФPSII, a proxy for photosynthesis. Results suggested that yield gain in transgenics could be associated with increased ФPSII, and the production of longer, thinner ears with more kernels. ictB localized primarily to the microsome fraction of leaf bundle-sheath cells, but not to chloroplasts. Extramembrane domains of ictB interacted in vitro with proteins involved in photosynthesis and carbohydrate metabolism. To our knowledge, this is the first published evidence of ictB insertion into a species using C4 photosynthesis and the largest-scale demonstration of grain yield enhancement from ictB insertion in planta. Results show that ictB is a valuable yield gene in the economically important crop maize, and are an important proof of concept that transgenic manipulation of photosynthesis can be used to create economically viable crop improvement traits.
Subject(s)
Cyanobacteria/metabolism , Photosynthesis/genetics , Zea mays/metabolism , Argentina , Biomass , Carbohydrate Metabolism/genetics , Carbohydrates/biosynthesis , Carbohydrates/genetics , Carbon Cycle , Carbon Dioxide/metabolism , Chlorophyll/metabolism , Chloroplasts/metabolism , Crop Production , Cyanobacteria/genetics , Membrane Proteins/genetics , Midwestern United States , Plant Leaves/metabolism , Plants, Genetically Modified/genetics , Plants, Genetically Modified/metabolism , Zea mays/genetics , Zea mays/growth & developmentABSTRACT
The photosynthesis process is determined by the intensity level and spectral quality of the light; therefore, leaves need to adapt to a changing environment. The incident energy absorbed can exceed the sink capability of the photosystems, and, in this context, photoinhibition may occur in both photosystem II (PSII) and photosystem I (PSI). Quantum yield parameters analyses reveal how the energy is managed. These parameters are genotype-dependent, and this genotypic variability is a good opportunity to apply mapping association strategies to identify genomic regions associated with photosynthesis energy partitioning. An experimental and mathematical approach is proposed for the determination of an index which estimates the energy per photon flux for each spectral bandwidth (Δλ) of the light incident (QI index). Based on the QI, the spectral quality of the plant growth, environmental lighting, and the actinic light of PAM were quantitatively very similar which allowed an accurate phenotyping strategy of a rice population. A total of 143 genomic single regions associated with at least one trait of chlorophyll fluorescence were identified. Moreover, chromosome 5 gathers most of these regions indicating the importance of this chromosome in the genetic regulation of the photochemistry process. Through a GWAS strategy, 32 genes of rice genome associated with the main parameters of the photochemistry process of photosynthesis in rice were identified. Association between light-harvesting complexes and the potential quantum yield of PSII, as well as the relationship between coding regions for PSI-linked proteins in energy distribution during the photochemical process of photosynthesis is analyzed.
Subject(s)
Chlorophyll , Genome-Wide Association Study , Light , Photosynthesis/genetics , Photosystem II Protein Complex/genetics , Photosystem II Protein Complex/metabolism , Plant Leaves/metabolismABSTRACT
Previously regarded as an intriguing photosynthetic curiosity, the occurrence of C4 and Crassulacean acid metabolism (CAM) photosynthesis within a single organism has recently emerged as a source of information for future biotechnological use. Among C4/CAM facultative species, Portulaca oleracea L. has been used as a model for biochemical and gene expression analysis of C4/CAM under field and laboratory conditions. In the present work, we focussed on developing molecular tools to facilitate functional genomics studies in this species, from the optimisation of RNA isolation protocols to a method for stable genetic transformation. Eleven variations of RNA extraction procedures were tested and compared for RNA quantity and quality. Also, 7 sample sets comprising total RNA from hormonal and abiotic stress treatments, distinct plant organs, leaf developmental stages, and subspecies were used to select, among 12 reference genes, the most stable reference genes for RT-qPCR analysis of each experimental condition. Furthermore, different explant sources, Agrobacterium tumefaciens strains, and regeneration and antibiotic selection media were tested in various combinations to optimise a protocol for stable genetic transformation of P. oleracea. Altogether, we provide essential tools for functional gene analysis in the context of C4/CAM photosynthesis, including an efficient RNA isolation method, preferred reference genes for RT-qPCR normalisation for a range of experimental conditions, and a protocol to produce P. oleracea stable transformants using A. tumefaciens.
Subject(s)
Portulaca , Carbon Dioxide , Crassulacean Acid Metabolism , Genomics , Photosynthesis/genetics , Portulaca/geneticsABSTRACT
Pfaffia glomerata possesses potential pharmacological and medicinal properties, mainly owing to the secondary metabolite 20-hydroxyecdysone (20E). Increasing production of biomass and 20E is important for industrial purposes. This study aimed to evaluate the influence of irradiance on plant morphology and production of 20E in P. glomerata grown in vitro. Nodal segments of accessions 22 and 43 (Ac22 and Ac43) were inoculated in culture medium containing MS salts and vitamins. Cultures were maintained at 25 ± 2 °C under a 16-h photoperiod and subjected to irradiance treatments of 65, 130, and 200 µmol m-2 s-1 by fluorescent lamps. After 30 days, growth parameters, pigment content, stomatal density, in vitro photosynthesis, metabolites content, and morphoanatomy were assessed. Notably, Ac22 plants exhibited 10-fold higher 20E production when cultivated at 200 µmol m-2 s-1 than at 65 µmol m-2 s-1, evidencing the importance of light quantity for the accumulation of this metabolite. 20E production was twice as high in Ac22 as in Ac43 plants although both accessions responded positively to higher irradiance. Growth under 200 µmol m-2 s-1 stimulated photosynthesis and consequent biomass accumulation, but lowered carotenoids and anthocyanins. Furthermore, increasing irradiance enhanced the number of palisade and spongy parenchyma cells, enhancing the overall growth of P. glomerata. Graphical abstract.