Rubisco Research Articles

Ecotoxicological assessment of copper and zinc in a common aquatic plant Ceratophyllum demersum: Physiological effects and biomarker responses

Utilizing and discharging chemical products containing trace metals lead to widespread contamination in the aquatic environment. Although copper (Cu) and zinc (Zn) are essential plant micronutrients, excessive concentrations may induce stress and mortality. This study investigated the physiological responses of a common aquatic plant, Ceratophyllum demersum, exposed to Cu (0, 2, 5, 10, and 50 μM) or Zn (0, 50, 100, 500, and 1000 μM) for 3 days. Both Cu and Zn were accumulated in plant tissues. Cu exposure led to severe phytotoxicity effects, manifested as a rapid decrease in photosynthetic efficiency (Fv/Fm and ՓPSII), a significant reduction in pigments and an increase in oxidative stress markers. In contrast, minor effects were observed in Zn-treated plants. In addition, Cu exposure suppressed the expression of D1, rubisco large subunit, and alpha-tubulin proteins but did not affect the PSI-B core subunit of PSI. Our study suggested that Cu is a potent phytotoxin by disturbing the principal reactions of photosynthesis and inducing oxidative stress and protein degradation. The overall health status of C. demersum was assessed by adopting the biomarker response index (BRI) approach. The effects of Cu were categorized as moderate in 2 μM and severe in 5, 10, and 50 μM whereas the effects of Zn were categorized as slight in 50 μM, negligible in 100 μM and major in 500 and 1000 μM. BRI effectively substantiates data interpretation of complex plant responses to trace metals and should be further adapted into biomonitoring suites in aquatic systems.

Immunoglobulin E-specific allergens against leaf in serum of dogs with clinical features of grass leaf allergy.

Grass leaf has been suspected of causing immunoglobulin (Ig)E-mediated immediate hypersensitivity reactions in humans and dogs. However, most studies in this area are case-control studies without in vitro data showing the involvement of IgE in the reaction. Laboratory studies have demonstrated the reactivity to a 50-55 kDa protein with clinical signs immediately after contact with grass leaf material. The clinical findings of dogs with atopic-like dermatitis immediately after contact with grass leaf material suggest the involvement of grass leaves as the allergen source. This study was designed to test the IgE-reactivity of grass leaf proteins in dogs with clinical signs and positive scratch test results against grass leaf material. The serum of 41 patients with a history of allergy and suspected to grass leaf material was immunoblotted against grass leaf extracts from five suspected grass species. The IgE-positive blots were separated with 2D gel electrophoresis and analysed with mass spectrometry (MS). Commercially supplied proteins were used to validate immunoblot activity. The serum of 25 dogs diagnosed with grass dermatitis had positive IgE-specific immunoblot against one or more grass leaf extracts. The MS data indicated a reactive band at 55 kDa to be beta-amylase or RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase) large subunit (RbLS). All tested dog sera showed IgE-reactivity with beta-amylase and some with RbLS. Canines with clinical signs of grass-related dermatitis had IgE-reactivity against grass leaf proteins. Serum IgE-reactivity to beta-amylase and RuBisCO large subunit may indicate that these proteins act as allergens, possibly causing pruritus and skin lesions.

CpDNA Sekansları Temelinde Trifolium L. Türlerinin Filogenetik İlişkileri

DNA barcoding is an important molecular approach in the determination of species diversity, evaluation of phylogenetic relationships and identification of taxonomically problematic species because of insufficient diagnostic characters. It has great importance to determine the barcoding regions that will give the best result in the evaluation of phylogenetic relationships in species like Trifolium that spread over wide geographical regions in the world and show high variation accordingly. For this aim, matK (maturase K) and rbcL (ribulose bisphosphate carboxylase gene) regions belonging to cpDNA(chloroplast DNA) was used to determine the barcoding ability and evaluate the taxonomy of the genus Trifolium. 63 taxa from matK region and 47 taxa from rbcL region were determined and used in this study. It was observed that transitional substitutions for matK and rbcL regions are higher than transversional substitutions with the rate of 51.52 % and 70.69 %, respectively. It can be stated that both of barcoding regions are valuable to reveal the phylogenetic relationships, in addition to their grouping ability the species as taxonomically. However, especially the using of matK sequence informations that have high variable sites (158) and grouping ability clearly for all taxa is strongly recommended.

Characterization of a novel thermophilic cyanobacterium within Trichocoleusaceae, Trichothermofontia sichuanensis gen. et sp. nov., and its CO2-concentrating mechanism.

Thermophiles from extreme thermal environments have shown tremendous potential regarding ecological and biotechnological applications. Nevertheless, thermophilic cyanobacteria remain largely untapped and are rarely characterized. Herein, a polyphasic approach was used to characterize a thermophilic strain, PKUAC-SCTB231 (hereafter B231), isolated from a hot spring (pH 6.62, 55.5°C) in Zhonggu village, China. The analyses of 16S rRNA phylogeny, secondary structures of 16S-23S ITS and morphology strongly supported strain B231 as a novel genus within Trichocoleusaceae. Phylogenomic inference and three genome-based indices further verified the genus delineation. Based on the botanical code, the isolate is herein delineated as Trichothermofontia sichuanensis gen. et sp. nov., a genus closely related to a validly described genus Trichocoleus. In addition, our results suggest that Pinocchia currently classified to belong to the family Leptolyngbyaceae may require revision and assignment to the family Trichocoleusaceae. Furthermore, the complete genome of Trichothermofontia B231 facilitated the elucidation of the genetic basis regarding genes related to its carbon-concentrating mechanism (CCM). The strain belongs to β-cyanobacteria according to its β-carboxysome shell protein and 1B form of Ribulose bisphosphate Carboxylase-Oxygenase (RubisCO). Compared to other thermophilic strains, strain B231contains a relatively low diversity of bicarbonate transporters (only BicA for HCO3- transport) but a higher abundance of different types of carbonic anhydrase (CA), β-CA (ccaA) and γ-CA (ccmM). The BCT1 transporter consistently possessed by freshwater cyanobacteria was absent in strain B231. Similar situation was occasionally observed in freshwater thermal Thermoleptolyngbya and Thermosynechococcus strains. Moreover, strain B231 shows a similar composition of carboxysome shell proteins (ccmK1-4, ccmL, -M, -N, -O, and -P) to mesophilic cyanobacteria, the diversity of which was higher than many thermophilic strains lacking at least one of the four ccmK genes. The genomic distribution of CCM-related genes suggests that the expression of some components is regulated as an operon and others in an independently controlled satellite locus. The current study also offers fundamental information for future taxogenomics, ecogenomics and geogenomic studies on distribution and significance of thermophilic cyanobacteria in the global ecosystem.

Transcriptomics Combined with Photosynthetic Physiology and Leaf Structure Analysis Revealed Increased Sugarcane Yield by Fenlong-Ridging

Fenlong-ridging (FL) is a new type of conservation tillage. In many crops, FL increases crop yield and quality; however, the cytology and molecular mechanisms of crops under FL is not completely understood. This study investigated soil physical and chemical properties under FL and conventional tillage (CK) during 2018–2019 (plant cane) and 2019–2022 (first stubble), and analyzed the agronomic trait, physiology, leaf anatomical structure, and gene expression related to photosynthesis between FL and CK of sugarcane (Guitang 42). Soil bulk density significantly increased, and soil porosity, water storage, and content of available nitrogen and phosphorus under FL were significantly higher than those under CK. Plant height, stem diameter, single stem weight, effective stem number and yield significantly increased under FL compared to under CK. Sugar content significantly increased in plant cane under FL. Chlorophyll content and the photosynthetic rate increased, with significantly higher activity of photosynthetic enzymes including NADP-malate dehydrogenase (NADP-MDH), phosphoenolpyruvate carboxylase (PEPC), and ribulose-1,5-bisphosphate carboxylase (RuBPC) under FL compared to CK. Fenlong-ridging cytology results showed that the mesophyll cells were large and arranged well, the Kranz anatomy was noticeable, and there were a high number of large chloroplasts in mesophyll cell and in the vascular bundle sheath. Furthermore, the bundle sheath in FL was larger than that in CK. Transcriptomics results showed that 19,357 differentially genes (DEGs) were up-regulated and 28,349 DEGs were down-regulated in sugarcane leaves under FL vs. CK. The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed that abundant DEGs were enriched in photosynthesis, photosynthesis-antenna protein, carotenoid biosynthesis, and other pathways associated with photosynthesis. Most expression was up-regulated, thus, facilitating photosynthesis regulation. Quantitative real-time polymerase chain reaction analysis revealed the up-regulation of genes related to photosynthesis (PsaH and PsbS) under FL. Overall, this study provides insights into the role of FL in increased sugarcane yield by integrating physiology, cytology, and proteomics analysis. These findings could be used to further improve its application and promotion.

Effect of nano-calcium carbonate on morphology, antioxidant enzyme activity and photosynthetic parameters of wheat (Triticum aestivum L.) seedlings

To meet the human demand for crop productivity, there are several challenges that researchers are involved in the photosynthetic efficiency of plants may be one of them. Nanotechnology can improve agricultural productivity by affecting the photosynthetic activity of plants. However, no studies have yet shown that nano-calcium carbonate (NCC) can play a role in improving photosynthetic performance of plants. In order to explore the effects of NCC on wheat seedling morphology, antioxidant enzyme activities and photosynthetic parameters, wheat roots were exposed to different concentrations of NCC (0, 25, 50, 100, 200, 400 mg L−1) through hydroponic experiments. Different concentrations affected root length, root surface area, root diameter, root volume and plant dry biomass. Compared to the control (0 mg L−1 of NCC) application (CK), wheat with 200 mg L−1 of NCC application showed 54% and 58% increase in superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities, respectively. As for photosynthesis-related physiological indicators, compared with CK, 200 mg L−1 of NCC significantly enhanced chlorophyll a (38%), chlorophyll b (20%), carotenoid content (19%), Rubisco activity (3.02-fold), net photosynthetic rate (Pn, 56%), transpiration rate (Tr, 40%), and stomatal conductance (Gs, 71%). The PCR results showed that compared with CK, the psbA gene encoding the photosystem PSII reaction center D1 protein and the rbcL gene encoding the large subunit of Rubisco were up-regulated by 2.56- and 2.58-fold at 200 mg L−1 NCC treatment, and by 3.22- and 3.57-fold at 400 mg L−1 NCC treatment, respectively. Specifically, NCC has significant benefits on wheat seedling growth, and 200 mg L−1 is the optimal concentration. NCC enhanced photosynthetic performance of wheat by increasing antioxidant enzyme activity, photosynthetic pigment content, Rubisco activity, stomatal conductance and PSII reaction center activity.Graphical

Increased Biomass and Polyhydroxybutyrate Production by Synechocystis sp. PCC 6803 Overexpressing RuBisCO Genes.

The overexpression of the RuBisCO (rbc) gene has recently become an achievable strategy for increasing cyanobacterial biomass and overcoming the biocompound production restriction. We successfully constructed two rbc-overexpressing Synechocystis sp. PCC 6803 strains (OX), including a strain overexpressing a large subunit of RuBisCO (OXrbcL) and another strain overexpressing all large, chaperone, and small subunits of RuBisCO (OXrbcLXS), resulting in higher and faster growth than wild type under sodium bicarbonate supplementation. This increased biomass of OX strains significantly contributed to the higher polyhydroxybutyrate (PHB) production induced by nutrient-deprived conditions, in particular nitrogen (N) and phosphorus (P). As a result of higher PHB contents in OX strains occurring at days 7 and 9 of nutrient deprivation, this enhancement was apparently made possible by cells preferentially maintaining their internal lipids while accumulating less glycogen. The OXrbcLXS strain, with the highest level of PHB at about 39 %w/dry cell weight (DCW) during 7 days of BG11-NP treatment, contained a lower glycogen level (31.9 %w/DCW) than wild type control (40 %w/DCW). In contrast, the wild type control strain exposed to N- and NP-stresses tended to retain lipid levels and store more glycogen than PHB. In this model, we, for the first time, implemented a RuBisCO-overexpressing cyanobacterial factory for overproducing PHB, destined for biofuel and biomaterial biotechnology.

DNA Barcoding, Phylogenetic Analysis and Secondary Structure Predictions of Nepenthes ampullaria, Nepenthes gracilis and Nepenthes rafflesiana.

Nepentheceae, the most prominent carnivorous family in the Caryophyllales order, comprises the Nepenthes genus, which has modified leaf trap characteristics. Although most Nepenthes species have unique morphologies, their vegetative stages are identical, making identification based on morphology difficult. DNA barcoding is seen as a potential tool for plant identification, with small DNA segments amplified for species identification. In this study, three barcode loci; ribulose-bisphosphate carboxylase (rbcL), intergenic spacer 1 (ITS1) and intergenic spacer 2 (ITS2) and the usefulness of the ITS1 and ITS2 secondary structure for the molecular identification of Nepenthes species were investigated. An analysis of barcodes was conducted using BLASTn, pairwise genetic distance and diversity, followed by secondary structure prediction. The findings reveal that PCR and sequencing were both 100% successful. The present study showed the successful amplification of all targeted DNA barcodes at different sizes. Among the three barcodes, rbcL was the least efficient as a DNA barcode compared to ITS1 and ITS2. The ITS1 nucleotide analysis revealed that the ITS1 barcode had more variations compared to ITS2. The mean genetic distance (K2P) between them was higher for interspecies compared to intraspecies. The results showed that the DNA barcoding gap existed among Nepenthes species, and differences in the secondary structure distinguish the Nepenthes. The secondary structure generated in this study was found to successfully discriminate between the Nepenthes species, leading to enhanced resolutions.

Plant-Growth Promoting Microbes Change the Photosynthetic Response to Light Quality in Spinach.

In this study, the combined effect of plant growth under different light quality and the application of plant-growth-promoting microbes (PGPM) was considered on spinach (Spinacia oleracea L.) to assess the influence of these factors on the photosynthetic performance. To pursue this goal, spinach plants were grown in a growth chamber at two different light quality regimes, full-spectrum white light (W) and red-blue light (RB), with (I) or without (NI) PGPM-based inoculants. Photosynthesis-light response curves (LRC) and photosynthesis-CO2 response curves (CRC) were performed for the four growth conditions (W-NI, RB-NI, W-I, and RB-I). At each step of LRC and CRC, net photosynthesis (PN), stomatal conductance (gs), Ci/Ca ratio, water use efficiency (WUEi), and fluorescence indexes were calculated. Moreover, parameters derived from the fitting of LRC, such as light-saturated net photosynthesis (PNmax), apparent light efficiency (Qpp), and dark respiration (Rd), as well as the Rubisco large subunit amount, were also determined. In not-inoculated plants, the growth under RB- regime improved PN compared to W-light because it increased stomatal conductance and favored the Rubisco synthesis. Furthermore, the RB regime also stimulates the processes of light conversion into chemical energy through chloroplasts, as indicated by the higher values of Qpp and PNmax in RB compared to W plants. On the contrary, in inoculated plants, the PN enhancement was significantly higher in W (30%) than in RB plants (17%), which showed the highest Rubisco content among all treatments. Our results indicate that the plant-growth-promoting microbes alter the photosynthetic response to light quality. This issue must be considered when PGPMs are used to improve plant growth performance in a controlled environment using artificial lighting.

Prospecting the biofuel potential of new microalgae isolates

The continued search and urgent need for renewable fuel sources have necessitated the exploration of microalgae to identify relevant species for making biofuels. The aim of the study was bioprospecting and screening native microalgae strains from freshwater habitats of the Almaty region, Kazakhstan, to assess the potential for producing biofuel. The studied strains demonstrated simultaneous biomass productivity, lipid productivity, suitable fatty acid composition, and biodiesel properties. The sequence analysis of the ribosomal DNA internal transcribed spacer partial region and ribulose-bisphosphate carboxylase gene (rbcL) led to the identification of five microalgae: Monoraphidium griffithii ZBD-01, Nephrochlamys subsolitaria ZBD-02, Ankistrodesmus falcatus ZBD-03, Parachlorella kessleri ZBD-04, and Desmodesmus pannonicus ZBD-05. P. kessleri had the highest biomass production (1.42 ± 0.08 g L−1 day−1), lipid productivity (29 ± 1.2 g L−1day−1), and C16–C18 fatty acid contents (90%), followed by A. falcatus and M. griffithi. Gas chromatography/mass spectrometry analysis indicated that the dominant fatty acids in these strains were palmitic, stearic, and oleic acids. The calculated biodiesel properties of P. kessleri and A. falcatus based on fatty acid methyl esters (FAME) profiles showed relatively good fuel properties (cetane numbers - 48 and 50; iodine and saponification values - 83.4 and 103.6 g I₂/100 g oil, 260.8 and 199.5 mg KOH g−1), which correlate well with. Our results suggest that P. kessleri and A. falcatus are promising strains for biodiesel production due to their high lipid productivity, fatty acid profile with relatively high content of oleic acid, and suitable biodiesel properties. The isolated native species of microalgae from natural freshwater bodies of the Almaty region present opportunities for further exploitation for the sustainable production of biomass and biodiesel.

Phenotypic Evaluation of Traits and Barcode Identification using Plastid-specific Ribulose Bisphosphate Carboxylase (Rbcl) Analysis on Lablab Beans [Lablab purpureus (L.) Sweet

Background: The importance of grain legumes in world food sustainability cannot be overemphasized. Minor legumes on the other hand, contribute to agricultural strengthening, especially in the context of sustainable crop and livestock production systems. In the context of assessing different legume species for crop improvement and identification, twenty (20) accessions of Lablab purpureus (L.) Sweet collected to determine the degree of trait variability and to identify accessions with potentials, which can contribute to grain and forage production. Methods: The present study involved the evaluation of twenty (20) accessions of Lablab purpureus (L.) Sweet from IITA, Ibadan. The accessions were grown in the experimental plot and DNA from young and healthy leaves were isolated for determination of genetic diversity using ribulose bisphosphate carboxylase (rbcL). The accessions were also categorized into groups based on the performances and the highest discriminating traits that accounted for greater variability using principal component analysis (PCA) and cluster analysis (CA) respectively. Result: Cluster analysis grouped all the twenty accessions into three clusters, where cluster I, cluster II and cluster III comprised of eight, seven and five accessions respectively. The PCA revealed hundred seed-weights, number of pod per plant and seed length as the most discriminating trait that accounted for greater variability in the Lablab accessions considered and they should be considered in the hyacinth bean improvement programs. Based on diverse level of phenotypic traits, accessions from each cluster were selected for barcode identification and comparison with other cultivars from other region. Results of the molecular analysis showed two clusters and authenticated the use of universal primers, ribulose bisphosphate carboxylase (rbcL) for DNA barcoding for successful amplification, identification and discrimination of Lablab purpureus (L). This revealed diversity of the considered accessions and provided information on relatedness to other accessions from other region of the world.

Diatom DNA metabarcoding to assess the effect of natural radioactivity in mineral springs on ASV of benthic diatom communities

Little is still known about the low dose effects of radiation on the microbial communities in the environment. Mineral springs are ecosystems than can be affected by natural radioactivity. These extreme environments are, therefore, observatories for studying the influence of chronic radioactivity on the natural biota. In these ecosystems we find diatoms, unicellular microalgae, playing an essential role in the food chain. The present study aimed to investigate, using DNA metabarcoding, the effect of natural radioactivity in two environmental compartments (i.e. spring sediments and water) on the genetic richness, diversity and structure of diatom communities in 16 mineral springs in the Massif Central, France. Diatom biofilms were collected during October 2019, and a 312 bp region of the chloroplast gene rbcL (coding for the Ribulose Bisphosphate Carboxylase) used as a barcode for taxonomic assignation. A total of 565 amplicon sequence variants (ASV) were found. The dominant ASV were associated with Navicula sanctamargaritae, Gedaniella sp., Planothidium frequentissimum, Navicula veneta, Diploneis vacillans, Amphora copulata, Pinnularia brebissonii, Halamphora coffeaeformis, Gomphonema saprophilum, and Nitzschia vitrea, but some of the ASVs could not be assigned at the species level. Pearson correlation failed to show a correlation between ASV’ richness and radioactivity parameters. Non-parametric MANOVA analysis based on ASVs occurrence or abundances revealed that geographical location was the main factor influencing ASVs distribution. Interestingly, 238U was the second factor that explained diatom ASV structure. Among the ASVs in the mineral springs monitored, ASV associated with one of the genetic variants of Planothidium frequentissimum was well represented in the springs and with higher levels of 238U, suggesting its high tolerance to this particular radionuclide. This diatom species may therefore represent a bio-indicator of high natural levels of uranium.

Molecular identification and high fidelity micropropagation of shell ginger (Alpinia zerumbet)

Alpinia zerumbet is a medicinal and ornamental plant of the Zingiberaceae family cultivated in many parts of the world. The plant is medicinally important and often misidentified with closely related species. The objective of this work was to establish its DNA-based identity and a protocol for high-fidelity micropropagation to support the medicinal plant industry. PCR amplification and subsequent sequencing of RuBisCO large subunit (rbcL) and Maturase K (matK) gene successfully report its DNA barcode. In vitro shoots were induced the best from rhizome buds on Murashige and Skoog (MS) medium supplemented with 6.0 mg L−1 6-benzyl amino purine and 30 g L−1 sucrose. Microshoots were rooted well in MS medium amended with 1.5 mg L−1 naphthalene acetic acid. Plantlets were satisfactorily acclimated to soils maintained in a growth chamber and subsequently in the open air for 10–20 days. Analyzing eight random amplified polymorphic DNA and eight inter-simple sequence repeat primers resulted in 53 and 60 distinct bands, respectively. Uniform banding patterns suggest the genetic uniformity of the micropropagated plants. The results offer an accurate identification of A. zerumbet from any plant tissue. The micropropagation protocol would be helpful for economically feasible and environmentally sustainable exploitation of this valuable plant.

Pinpointing Synechococcus Rubisco large subunit sections involved in heterologous holoenzyme formation in Escherichia coli

Pinpointing Synechococcus Rubisco large subunit sections involved in heterologous holoenzyme formation in Escherichia coli

Biophysical models for studying patterns of RuBisCO small subunit evolution.

For much of Earth's history, key enzymes have dominated the conversion of energy into the production of biomass. This history extends hundreds of millions of years into the past, but the available record provides few direct indicators of the emergence and evolution of enzymes that shaped our planet. A good example is Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO), which is responsible for the fixation of CO2 in conjunction with oxygenic photosynthesis and is estimated to be the most abundant enzyme on Earth. RuBisCO form-I is the only form composed of a large and small subunit. The biochemical role that the small subunit plays is unclear, and the circumstances of its coevolution with the large subunit or with drastic changes to the Earth's surface environment such as the concentrations of CO2 and O2 gases are also unknown. Here, we explore how the small subunit-mediated RuBisCO form-I transition by generating a phylogenetic tree of proteins, reconstructing its ancestral sequences, and analyzing the structure as well as function of the ancestral large-small subunit RuBisCO complexes. From ancient and extant structures, we identify the general attributes that define the interaction between the two RuBisCO subunits and inspect how these interactions have evolved with reference to the ancestral large subunit RuBisCO forms and the partition and diffusion of CO2 and O2 at different relative concentrations of the two gasses. Our results are consistent with the possibility that the small subunit was an evolutionary response to the global rise of atmospheric O2 over 2 billion years ago, and that it impacted large subunit CO2 diffusion. Our research highlights how a protein subunit that emerged billions of years ago in response to a change in the planet's atmosphere impacts the function of an essential protein complex.

The Effects of Enhanced Ultraviolet-B Radiation on Leaf Photosynthesis and Submicroscopic Structures in Mangifera indica L. cv. ‘Tainong No 1’

Objective: In the future, the stress of enhanced UV-B radiation on the Earth will first affect the photosynthesis of plants, including mangoes. Therefore, it is necessary to study the effects of enhanced UV-B radiation on the photosynthesis of mangoes. Methods: ‘Tainong No 1’ mango trees in the field were selected as the experimental material and divided into 2 groups: one group was shined under 96 kJ·m−2·d−1 UV-B lamps for artificially simulated treatment of enhanced UV-B radiation, and the other group was shined under sunshine directly as the control (CK). The main photosynthetic physiological indicators were measured with conventional methods, and the expression levels of the genes encoding large and small subunits of the Rubisco enzyme were measured with fluorescent qPCR. The changes in stomatal morphology and chloroplast structure were observed with scanning electron microscopy and transmission electron microscopy. Results: The content of malondialdehyde (MDA) and the relative conductivity in the leaves of the treatment tended to be significantly higher than those of the CK. The net photosynthetic rate (Pn) of the treatment tended to decrease and be lower than that of CK. The dynamics of intercellular CO2 concentration (Ci) of the treatment and CK changed differently from each other but generally tended to decrease, and that of the treatment tended to be significantly higher than that of CK. The stomatal conductance (Gs) of the treatment and CK both generally decreased, and that of the treatment was always significantly lower than that of CK. The contents of chlorophyll a, chlorophyll b and total chlorophyll and the ratio of chlorophyll a/b of the treatment were lower than those of CK, while the carotenoid content showed the opposite trend. The stomata and the surface of leaves of the treatment were sunken and damaged, respectively. The palisade tissue, spongy tissue and upper epidermis thickened more, and the total thickness significantly increased. Meanwhile, the ratio of palisade tissue to spongy tissue decreased. During treatment, the chloroplasts were swollen and shortened, the number of chloroplasts was reduced, the starch grains were degraded, and the grana lamella were distorted, loosely arranged and blurred. The expression of the genes encoding the Rubisco large subunit (rbcL) in the treatment was significantly inhibited, while that encoding the Rubisco small subunit (rbcS) decreased first and increased later. In conclusion, 96 kJ·m−2·d−1 enhanced UV-B radiation treatment caused damage to the leaf cell membrane system. This led to stomatal limitation of photosynthesis by destroying the stomatal structure and nonstomatal limitation of photosynthesis by damaging the submicrostructure of the chloroplasts and downregulating the expression of rbcL. The leaves may resist the photosynthetic damage caused by enhanced UV-B radiation by upregulating rbcS expression as much as possible.

Cell dehydration of intergeneric hybrid induces subgenome-related specific responses.

The aim was to identify subgenome-related specific responses in two types of triticale, that is, of the wheat-dominated genome (WDG) and rye-dominated genome (RDG), to water stress induced in the early phase (tillering) of plant growth. Higher activity of the primary metabolism of carbohydrates is a feature of the WDG type, while the dominance of the rye genome is associated with a higher activity of the secondary metabolism of phenolic compounds in the RDG type. The study analyzed carbohydrates and key enzymes of their synthesis, free phenolic compounds and carbohydrate-related components of the cell wall, monolignols, and shikimic acid (ShA), which is a key link between the primary and secondary metabolism of phenolic compounds. Under water stress, dominance of the wheat genome in the WDG type was manifested by an increased accumulation of the large subunit of Rubisco and sucrose phosphate synthase and a higher content of raffinose and stachyose compared with the RDG type. In dehydrated RDG plants, higher activity of L-phenylalanine ammonia lyase (PAL) and L-tyrosine ammonia lyase (TAL), as well as a higher level of ShA, free and cell wall-bound p-hydroxybenzoic acid, free homovanillic acid, free sinapic acid, and cell wall-bound syringic acid can be considered biochemical indicators of the dominance of the rye genome.

Tolerância à seca induzida pela superexpressão do gene nuclear rbcL em arroz

Abstract The objective of this work was to determine whether the overexpression of the nuclear Rubisco large subunit (rbcL) improves the drought tolerance of the genetically modified (GM) BRSMG Curinga upland rice (Oryza sativa) cultivar. GM and non-genetically modified (NGM) plants of the same cultivar were compared under the two following water treatments: well watered (WW) and water deficit (WD). The performance of the agronomic traits of GM plants, including grain yield, was superior to that of NGM plants in both treatments. By quantitative polymerase chain reaction, GM plants show a significantly higher expression of the rbcL gene in both WW and WD, as well as a larger amount of abscisic acid. With the RNAseq analysis, almost three times more upregulated genes are identified in GM plants in stage 2 after water restriction, indicating a greater protection against water deficit. The higher expression of genes related to the protection of the cellular metabolism and a series of physiological alterations may be involved in the increase in the drought tolerance of GM rice plants overexpressing the rbcL gene.

Morpho-Genetic Characterization of Abelmoschus Moench. Accessions

This study was carried out to assess the morphological and genetic variability of seven accessions of Abelmoschus L. species using morphometric analysis and ribulose bisphosphate carboxylase large chain (RBCL) molecular markers. Using a completely randomized block design, seeds of the okra accessions were planted with three replicates each. During the developmental stage, the morphological features of the accessions were observed and recorded according to the standard descriptor for the crop. Morphologically, all the accessions exhibited a degree of similarities, albeit, at maturity, the leaf, plant height, leaf colour, and leaf shape became distinct. A cluster of the phenotypic characterization was observed at a 3.74 level of coefficient of similarity with two distinct clusters, which were predicted to be A. esculentus and A. caillei. The percentage variance of the two principal components was 55.12% and 22.69% with corresponding Eigenvalues of 4.11 and 1.69, respectively. Results of the RBCL analysis revealed genetic variability at a 0.80 level of coefficient of similarity. Two distinguishable clusters were observed. Both morphometric and genotyping results suggest that variations exist among and within the seven accessions. In conclusion, there is a need to frequently evaluate plant genetic resources held in gene banks as they may not reflect the whole range of diversity inherent in the species.

New distribution record and DNA barcoding of Sapria himalayana Griff. (Rafflesiaceae), a rare and endangered holoparasitic plant from Mizoram, India

Sapria himalayana Griff. is a rare and endangered holoparasitic plant that prefers a specific host (Tetrastigma sp.). It is one of the lesser-known and poorly understood plants facing threats of extinction owing to human interference in the evergreen forests of Mizoram. The flower is the only visible part of this endophyte and blooms from November to December. The plant was encountered for the first time in the evergreen forest near Rullam village in the Serchhip District of Mizoram, India. In the present study, DNA barcoding was used to identify the plants, and the internal transcribed spacer 2 (ITS2) region of S. himalayana was amplified and sequenced. The ITS2 sequence could accurately identify up to the species level for this endangered species. The absence of the ribulose-biphosphate carboxylase gene (rbcL) region in the genome supports its holoparasitic nature. Hence, DNA barcoding can help in taxonomic and biodiversity research and aid in selecting taxa for various molecular ecology and population genetics studies. The phylogenetic tree was analyzed using the maximum-likelihood method, and our findings showed that species from different families were clearly discriminated in a phylogenetic tree. To the best of our knowledge, this is the first report of DNA barcoding using ITS2 region of S. himalayana from Mizoram, India.