RESUMO
Brassinosteroids (BRs) are an important group of polyhydroxylated naturally occurring steroidal phytohormones found in the plant kingdom in extremely low amounts. Due to the low concentrations in which these compounds are found, much effort has been dedicated to synthesizing these compounds or their structural analogs using natural and abundant sterols. In this work, we report the synthesis of new brassinosteroid analogs obtained from hyodeoxycholic acid, with a 3,6 dioxo function, 24-Nor-22(S)-hydroxy side chain and p-substituted benzoate function at C-23. The plant growth activities of these compounds were evaluated by two different bioassays: rice lamina inclination test (RLIT) and BSI. The results show that BRs' analog with p-Br (compound 41f) in the aromatic ring was the most active at 1 × 10-8 M in the RLIT and BSI assays. These results are discussed in terms of the chemical structure and nature of benzoate substituents at the para position. Electron-withdrawing and size effects seems to be the most important factor in determining activities in the RLIT assay. These results could be useful to propose a new structural requirement for bioactivity in brassinosteroid analogs.
Assuntos
Benzoatos , Brassinosteroides , Oryza , Brassinosteroides/química , Brassinosteroides/síntese química , Oryza/crescimento & desenvolvimento , Oryza/efeitos dos fármacos , Oryza/metabolismo , Benzoatos/química , Benzoatos/farmacologia , Benzoatos/síntese química , Reguladores de Crescimento de Plantas/síntese química , Reguladores de Crescimento de Plantas/química , Reguladores de Crescimento de Plantas/farmacologia , Desenvolvimento Vegetal/efeitos dos fármacos , Ácido DesoxicólicoRESUMO
Sulfur (S) is an essential macronutrient for plants and its availability in soils is an important determinant for growth and development. Current regulatory policies aimed at reducing industrial S emissions together with changes in agronomical practices have led to a decline in S contents in soils worldwide. Deficiency of sulfate-the primary form of S accessible to plants in soil-has adverse effects on both crop yield and nutritional quality. Hence, recent research has increasingly focused on unraveling the molecular mechanisms through which plants detect and adapt to a limiting supply of sulfate. A significant part of these studies involves the use of omics technologies and has generated comprehensive catalogs of sulfate deficiency-responsive genes and processes, principally in Arabidopsis together with a few studies centering on crop species such as wheat, rice, or members of the Brassica genus. Although we know that sulfate deficiency elicits an important reprogramming of the transcriptome, the transcriptional regulators orchestrating this response are not yet well understood. In this review, we summarize our current knowledge of gene expression responses to sulfate deficiency and recent efforts towards the identification of the transcription factors that are involved in controlling these responses. We further compare the transcriptional response and putative regulators between Arabidopsis and two important crop species, rice and tomato, to gain insights into common mechanisms of the response to sulfate deficiency.
Assuntos
Regulação da Expressão Gênica de Plantas , Redes Reguladoras de Genes , Sulfatos , Sulfatos/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/fisiologia , Oryza/genética , Oryza/metabolismo , Oryza/crescimento & desenvolvimentoRESUMO
BACKGROUND: Rice is one of the most consumed cereals in the world. Productivity losses are caused by different biotic stresses. One of the most common is the phytophagous mite Schizotetranychus oryzae Rossi de Simons (Acari: Tetranychidae), which inhibits plant development and seed production. The identification of plant defense proteins is important for a better understanding of the mite-plant interaction. We previously detected a high expression of Osmotin1 protein in mite-resistant rice cultivars, under infested conditions, suggesting it could be involved in plant defense against mite attack. We therefore aimed to evaluate the responses of three rice lines overexpressing Osmotin1 (OSM1-OE) and three lines lacking the Osmotin1 gene (osm1-ko) to mite attack. RESULTS: The numbers of individuals (adults, immature stages, and eggs) were significantly lower in OSM1-OE lines than those in wild-type (WT) plants. On the other hand, the osm1-ko lines showed larger numbers of mites per leaf than WT plants. When plants reached the full maturity stage, two out of the three infested OSM1-OE lines presented lower plant height than WT, while the three osm1-ko lines (infested or not) presented higher plant height than WT. The reduction in seed number caused by mite infestation was lower in OSM1-OE lines (12-19%) than in WT plants (34%), while osm1-ko lines presented higher reduction (24-54%) in seed number than WT plants (13%). CONCLUSION: These data suggest that Osmotin1 is involved in rice resistance to S. oryzae infestation. This is the first work showing increased plant resistance to herbivory overexpressing an Osmotin gene. © 2023 Society of Chemical Industry.
Assuntos
Infestações por Ácaros , Ácaros , Oryza , Tetranychidae , Humanos , Animais , Tetranychidae/genética , Tetranychidae/metabolismo , Oryza/genética , Oryza/metabolismo , Ácaros/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMO
We have previously shown that rice plants silenced for peroxisomal ascorbate peroxidase (OsAPX4-RNAi) display higher resilience to photosynthesis under oxidative stress and photorespiratory conditions. However, the redox mechanisms underlying that intriguing response remain unknown. Here, we tested the hypothesis that favorable effects triggered by peroxisomal APX deficiency on photosynthesis resilience under CAT inhibition are dependent on the intensity of photorespiration associated with the abundance of photosynthetic and redox proteins. Non-transformed (NT) and OsAPX4-RNAi silenced rice plants were grown under ambient (AC) or high CO2 (HC) conditions and subjected to 3-amino-1,2,4-triazole (3-AT)-mediated CAT activity inhibition. Photosynthetic measurements evidenced that OsAPX4-RNAi plants simultaneously exposed to CAT inhibition and HC lost the previously acquired advantage in photosynthesis resilience displayed under AC. Silenced plants exposed to environment photorespiration and CAT inhibition presented lower photorespiration as indicated by smaller Gly/Ser and Jo/Jc ratios and glycolate oxidase activity. Interestingly, when these silenced plants were exposed to HC and CAT-inhibition, they exhibited an inverse response compared to AC in terms of photorespiration indicators, associated with higher accumulation of proteins. Multivariate and correlation network analyses suggest that the proteomics changes induced by HC combined with CAT inhibition are substantially different between NT and OsAPX4-RNAi plants. Our results suggest that the intensity of photorespiration and peroxisomal APX-mediated redox signaling are tightly regulated under CAT inhibition induced oxidative stress, which can modulate the photosynthetic efficiency, possibly via a coordinated regulation of protein abundance and rearrangement, ultimately triggered by crosstalk involving H2O2 levels related to CAT and APX activities in peroxisomes.
Assuntos
Oryza , Oryza/metabolismo , Peróxido de Hidrogênio/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Fotossíntese , Estresse Oxidativo , Plantas/metabolismo , Ascorbato Peroxidases/metabolismoRESUMO
Rhizosphere soil of aromatic rice inhabits different fungal species that produce many bioactive metabolites including 2-acetyl-1-pyrroline (2AP). The mechanism for the biosynthesis of 2AP in the fungal system is still elusive. Hence, the present study investigates the role of possible nitrogen (N) precursors such as some amino acids and polyamines as well as the enzymes involved in 2AP synthesis in the fungal species isolated from the rhizosphere of aromatic rice varieties. Three fungal isolates were found to synthesize 2AP (0.32-1.07 ppm) and maximum 2AP was synthesized by Aspergillus niger (1.07 ppm) isolated from rhizosphere of Dehradun Basmati (DB). To determine the N source for 2AP synthesis, various N sources such as proline, glutamate, ornithine putrescine, spermine, and spermidine were used in place of putrescine in the synthetic medium (Syn18). The results showed that maximum 2AP synthesis was found with putrescine (1.07 ppm) followed by spermidine (0.89 ppm) and spermine (0.84 ppm). Further, LC-QTOF-MS analysis revealed the mobilization of spermine and spermidine into the putrescine, indicating that putrescine is the key N source for 2AP synthesis. Moreover, higher enzyme activity of DAO, PAO, and ODC as well as higher content of methylglyoxal metabolite in the A. niger NFCCI 5060 as compared to A. niger NFCCI 4064 (control) suggests the prominent role of these enzymes in the synthesis of 2AP. In conclusion, this study showed evidence of the polyamines mediated 2AP biosynthesis in A. niger NFCCI 5060.
Assuntos
Oryza , Poliaminas , Poliaminas/metabolismo , Espermidina/metabolismo , Putrescina/metabolismo , Espermina/metabolismo , Aspergillus niger/genética , Aspergillus niger/metabolismo , Oryza/metabolismo , Ornitina Descarboxilase/metabolismoRESUMO
The ideal rice phenotype is that of plants exhibiting fewer panicles with high biomass, large grain number, flag leaf area with small insertion angles, and an erected morphology improving light interception. The sunflower transcription factor HaHB11, homeodomain-leucine zipper I, confers increased seed yield and abiotic stress tolerance to Arabidopsis and maize. Here, we report the obtaining and characterization of rice plants expressing HaHB11 driven by its promoter or the 35S constitutive one. Transgenic p35S:HaHB11 plants closely resembled the ideal high-yield phenotype, whereas those carrying the pHaHB11:HaHB11 construct were hard to distinguish from the wild type. The former had an erected architecture, enhanced vegetative leaf biomass, rolled flag leaves with a larger surface, sharper insertion angles insensitive to brassinosteroids, and higher harvest index and seed biomass than the wild type. The combination of the distinct features exhibited by p35S:HaHB11 plants, including the increased number of set grains per panicle, supports the high-yield phenotype. We wondered where HaHB11 has to be expressed to achieve the high-yield phenotype and evaluated HaHB11 expression levels in all tissues. The results indicate that its expression is particularly necessary in the flag leaf and panicle to produce the ideal phenotype.
Assuntos
Arabidopsis , Oryza , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Oryza/genética , Oryza/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Fenótipo , Arabidopsis/genética , Grão Comestível/genética , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMO
This work describes the relationship between the complex of photosystem I and photosystem II in the senescence process of rice leaves observed through changes in the optical response. We studied three varieties of rice plants at different aging times using time-resolved photoluminescence to measure the time decay of the emission, and stationary photoluminescence, to measure the emission wavelength. The spectra obtained with the former technique were fitted with decreasing exponential functions. Two relaxation times were obtained, one ranging between 1.0 and 1.7 ns, and the other, from 5.0 to 10.5 ns. They are associated with the electron's deexcitation of PSI and PSII, respectively, and these decay times increase as the leaf senescence process takes place. The spectra obtained with stationary photoluminescence were fitted with Voigt functions. These spectra exhibit two main peaks around 683 and 730 nm, which could be associated mainly with PSII and PSI emissions, respectively. The PSI de-excitation exhibits higher dispersive processes because chlorophyll-a molecules in it move away from each other, decreasing their concentration. Therefore, it takes longer for electrons to recombine during photosynthesis, as seen in the time-resolve response. Articulating the results of both photoluminescence techniques, the changes in the response of the photosystems of the living rice leaves during senescence are evidenced.
Assuntos
Oryza , Oryza/metabolismo , Fotossíntese/fisiologia , Complexo de Proteína do Fotossistema II/metabolismo , Complexo de Proteína do Fotossistema I/metabolismo , Folhas de PlantaRESUMO
Honey is a special product widely appreciated because of its peculiar flavor and aroma as well as its beneficial effects on health due to its constituents. However, the use of honey in its natural form can present several disadvantages to the food industry because of its high viscosity and density. This work aimed to obtain honey powder using rice, pea, or a mixture of both proteins as carriers by spray drying and to characterize physiochemically. Also, the mass balance was performed to evaluate changes in humidity and temperature that occurred by the drying air during the process. The honey showed acceptable physicochemical parameters by the legislation of honey quality control in regard to color (143.43 ± 4.34) mm Pfund, free acidity (46.41 ± 0.53) meq/kg, pH (3.73 ± 0.03), fructose content (46.52 ± 0.56) g/100 g and glucose content (35.88 ± 0.16) g/100 g, which leads to the production of honey powder. Among the carriers tested, the honey powder using rice protein achieved the highest powder recovery yield at (64.88 ± 0.64) %. The physicochemical properties were evaluated and the phenolic compounds were not negatively affected by spray drying conditions, maintaining a value of gallic acid equivalent (GAE) content at (301.31 ± 20.95) mg/kg of honey. Therefore, this work shows honey as an alternative food ingredient in powdered form, including the growing market for using alternative protein.
Assuntos
Mel , Oryza , Proteínas de Ervilha , Mel/análise , Pós/química , Oryza/metabolismo , DessecaçãoRESUMO
We investigated SNPs in alternative oxidase (AOX) genes and their connection to ecotype origins (climate, altitude, and rainfall) by using genomic data sets of Arabidopsis and rice populations from 1190 and 90 ecotypes, respectively. Parameters were defined to detect non-synonymous SNPs in the AOX ORF, which revealed amino acid (AA) changes in AOX1c, AOX1d, and AOX2 from Arabidopsis and AOX1c from rice in comparison to AOX references from Columbia-0 and Japonica ecotypes, respectively. Among these AA changes, Arabidopsis AOX1c_A161E&G165R and AOX1c_R242S revealed a link to high rainfall and high altitude, respectively, while all other changes in Arabidopsis and rice AOX was connected to high altitude and rainfall. Comparative 3D modeling showed that all mutant AOX presented structural differences in relation to the respective references. Molecular docking analysis uncovered lower binding affinity values between AOX and the substrate ubiquinol for most of the identified structures compared to their reference, indicating better enzyme-substrate binding affinities. Thus, our in silico data suggest that the majority of the AA changes found in the available ecotypes will confer better enzyme-subtract interactions and thus indicate environment-related, more efficient AOX activity.
Assuntos
Arabidopsis , Oryza , Arabidopsis/metabolismo , Oryza/metabolismo , Ecótipo , Altitude , Simulação de Acoplamento Molecular , Proteínas de Plantas/metabolismo , Proteínas Mitocondriais/metabolismoRESUMO
DNA methylation is the most studied epigenetic trait. It is considered a key factor in regulating plant development and physiology, and has been associated with the regulation of several genomic features, including transposon silencing, regulation of gene expression, and recombination rates. Nonetheless, understanding the relation between DNA methylation and recombination rates remains a challenge. This work explores the association between recombination rates and DNA methylation for two commercial rice varieties. The results show negative correlations between recombination rates and methylated cytosine counts for all contexts tested at the same time, and for CG and CHG contexts independently. In contrast, a positive correlation between recombination rates and methylated cytosine count is reported in CHH contexts. Similar behavior is observed when considering only methylated cytosines within genes, transposons, and retrotransposons. Moreover, it is shown that the centromere region strongly affects the relationship between recombination rates and methylation. Finally, machine learning regression models are applied to predict recombination using the count of methylated cytosines in the CHH context as the entrance feature. These findings shed light on the understanding of the recombination landscape of rice and represent a reference framework for future studies in rice breeding, genetics, and epigenetics.