Protoplasma最新文献

Cauliflower Or gene governs massive accumulation of β-carotene in the edible 'curd' portion. However, homozygous dominant (OrOr) plants accumulate higher β-carotene than heterozygous (Oror) individuals, yet this phenomenon has not been thoroughly elucidated in relation to chromoplast morphology. A study was performed in a complete randomised block design with three replicates, in which curd samples of homozygous orange (OrOr; CF_Or-HM)_, heterozygous orange (Oror; CF_Or-HT) and white (oror; CF_WT) genotypes were analysed using transmission electron microscopy (TEM). The number of chromoplasts in a cell and their morphology (shape and size) exhibited significant variation in the genotypes. In CF_Or-HM genotypes, chromoplasts exhibited a membrane-like structure, but in CF_Or-HT, they were small granules. The number of chromoplasts was significantly higher in CF_Or-HM compared to CF_Or-HT. The CF_WT had leucoplasts instead of chromoplasts. The CF_Or-HM (15.1 ± 0.1 µg/g FW) had significantly higher β-carotene content than CF_Or-HT (5.6 ± 0.3 µg/g FW). Both CF_Or-HM and CF_Or-HT had 18 and 7 times higher β-carotene than the white counterpart CF_WT (0.8 ± 0.1 µg/g FW). The number and size of chromoplasts exhibit a strong correlation with the concentration of total carotenoids and β-carotene in the curd portion. This is the first systematic report on changes in chromoplast features associated with Or-gene zygosity in cauliflower.

Although sulfur (S) fertilizer is known to enhance flavor quality in S-rich pungent vegetables, its role in regulating non-S flavor compounds, such as capsaicinoids in peppers (Capsicum annuum L.), remains unclear. Here, field experiments were conducted using three treatments: S fertilizer (ammonium sulfate), nitrogen fertilizer (urea), and an unfertilized control (CK). Pepper yield, flavor compounds (capsaicinoids, soluble sugars, vitamin C, and volatiles), and rhizosphere microbiota were analyzed. The results showed that S fertilizer significantly increased the contents of soluble sugars, vitamin C, capsaicinoids, and 15 volatile compounds such as benzyl benzoate, (E,E)-2,4-nonadienal, and β-ionone, collectively achieving optimal pungent flavor. Moreover, S fertilizer reduced bacterial diversity and richness in the rhizosphere soil but exhibited minimal impact on fungal community structure. Notably, the bacterial genera unidentified_WD2101_oil_group and Rhizomicrobium were identified as potential key taxa enhancing capsaicinoid accumulation under S fertilizer. Additionally, Sphaerobacter (bacteria) and Pseudogymnoascus (fungi) emerged as critical microbial candidates driving the synthesis of volatile compounds in S-amended soils. This study provides new insights into the roles of rhizosphere microbiota under S fertilization, emphasizing their importance in improving pepper yield and quality.

Cell death is an essential part of both normal development and pathological processes. This review provides a bird's-eye view of the most important aspects of programmed cell death in different groups of organisms-bacteria, protists, fungi, and animals in comparison with plants-and highlights the possible tendencies in the evolution of cell death machinery.

Exposure to electromagnetic radiation (EMR) at varied power densities can profoundly affect fertilization in plants by posing physiological stress and impairing pollen's ability to fertilize. In the present study, four sites (under exposure to EMR at varied power densities) like S-1 (1 μW/cm²), S-2 (2.8 μW/cm²), S-3 (5.5 μW/cm²), and S-4 (15 μW/cm²) were selected for collection of pollen grain samples of 12 plant species naming Alcea rosea L., Centaurea cyanus L., Chrysanthemum coronarium L., Dahlia pinnata Cav., Gaillardia pulchella Foug., Jatropha integerrima Jacq., Papaver somniferum L., Rosa indica L., Tagetes erecta L., Tropaeolum majus L., Verbena pulchella Greene, and Catharanthus roseus L. pollen grain samples were collected from each site ensuring that availability of all selected plants occurred at all sites. Different staining methods, using aceto-orcein (AO), Alexander's (AS), 2,3,5 triphenyl tetrazolium chloride (TTC), and Lugol's (LS) stains, were followed to evaluate pollen viability. The study revealed that among all plant species, C. coronarium showed the minimum pollen viability with AO and TTC stains at S-1, S-2, and S-3 while T. erecta with AO and C. cyanus with TTC at S-4. P. somniferum showed minimum pollen viability with AS at all sites and with LS at S-3 and S-4 while R. indica and V. pulchella with LS at S-1 and 2, respectively. All plant species have shown maximum pollen viability using AO stain at all sites. TTC was found to be the effective staining method that resulted in minimum pollen viability for all plant species at all sites except for Alcea rosea at S-2 and 3 and P. somniferum at S-2 which showed minimum pollen viability with LS and AS, respectively. The association between increased EMR power density and reduced pollen viability across different sites points towards the harmful effects of EMR on plant reproduction.

Salinity disrupts the germination and growth of seedlings in plants and reduces the population of soil microorganisms, especially bacteria. Scientists have found that each normal soil contains 600 million bacteria, consisting of 20,000 species, and their number is reduced to 1 million bacteria, consisting of 5000 to 8000 species, under salt stress. Many engineering methods are not practical. One of the biological methods is seed inoculation with plant growth-promoting rhizobacteria (PGPR). PGPR improves the morphological traits of plants, which include 1 - extracellular plant growth-promoting rhizobacteria)ePGPR( and 2 - intracellular plant growth-promoting rhizobacteria)iPGPR(. ePGPRs are present in the rhizosphere, on the rhizosphere, or in the spaces between the cells of the root cortex, while iPGPRs are present inside the specialized nodular structures of the root cells. The aim of this experiment was to investigate the effect of several rhizobacterial isolates obtained from the rhizoplane of saline soil in Momghan on seed germination and wheat seedling growth at different salinity concentrations. The experiment was conducted using a randomized complete block design. The first factor had five levels: control, 3, 6, 12, and 18 ds/m, while the second factor, involved seed inoculation with 10 bacterial isolates. The experiments were carried out in 3 replications. Isolates R₂ and R₇ promoted the growth index. At salinity levels of 3 and 6 ds/m, a significant difference was observed at the 5% level. At concentrations of 12 and 18 ds/m, morphological traits improved growth. The isolates were identified using biochemical and molecular 16s rRNA tests. Isolate R₂ was placed in the genus Pseudomonas sp. and isolate R₇ in the species Serratia odorifera.

Nitric oxide (NO) functions as a signaling molecule in many biological processes in green algae and higher plants. Although the mechanisms of NO synthesis in most plants are the subject of ongoing research and debate, a functional NO synthase (NOS) has been characterized only in Ostreococcus tauri. To date, the question of whether NO synthesis occurs in other NOS-containing members of the class Mamiellophyceaea, which gave rise to the core Chlorophyta, has not been elucidated. We found that, like O. tauri, O. lucimarinus and Bathycoccus prasinos grow on arginine as the sole nitrogen source, and their NOSs function and produce NO in cells. Moreover, in O. tauri, O. lucimarinus, and B. prasinos, NO exerts its biological functions through protein S-nitrosylation. Collectively, our data suggest that both NO and S-nitrosylated proteins are important mediators in the process of cell growth in NOS-containing representatives of Mamiellophyceae. Thus, we have updated the data related to protein S-nitrosylation as an evolutionarily conserved mechanism regulating many aspects of cell signaling in plants.

Mutation of MEDIATOR 18 leads to death of highly proliferating cells within the Arabidopsis root apical meristem, which impairs root growth. Phosphate (Pi) is a macronutrient required to support mitotic activity in meristems, and its deficiency causes root growth inhibition; thus, we hypothesized that Pi availability could influence cell viability as well. With this in mind, in vitro experiments were performed varying the Pi concentration (0, 1, 10, and 250 µM) in the growth medium of Arabidopsis WT seedlings and med18-1 mutants to analyze meristem integrity and root hair development and correlate it with gene expression of selected promoter-reporter gene fusions. We found that WT (Col-0) seedlings entered the already reported determinate root growth program that terminates mitosis and differentiates primary root meristems at low (0, 1, and 10 µM) Pi concentrations. Unexpectedly, in marked contrast to the WT, med18-1 null mutant seedlings had healthy meristems under low Pi availability, and the cell death occurred only at high Pi (250 µM Pi). Root hair density and length were greater in med18-1 mutants than WT at all Pi concentrations tested. Gene expression analyses for cell cycle, auxin, and damage response as well as detection of hydrogen peroxide indicated that MED18 promotes the transit from cell division into differentiation of primary root tips induced by Pi starvation but protects the root meristem from genotoxic stress upon zeocin application. These results uncover an unexpected finding in which the lack of an essential macronutrient decreases the genotoxic pressure to highly proliferating plant cells.

The antioxidant defense mechanisms that shield eukaryotes from oxidative stress depend heavily on the enzyme catalase (CAT). These proteins, which are found in nearly all living creatures, perform crucial functions in regulating how plants react to biotic and abiotic stimuli by regulating the breakdown of H₂O₂. CAT is encoded by a small gene family in plants. In the current study, the first catalase gene from oat (Avena sativa L.) designated AsCAT1 was isolated and characterized. The corresponding AsCAT1 protein has 492 amino acids and presented a significant similarity with other catalase proteins in subfamily 1, according to phylogenetic study. A peroxisomal targeting signature (PTS1), as shown for other catalase proteins, is present at the C-terminal portion of AsCAT1 which confers a peroxisomal localization of this protein. AsCAT1 protein has a catalytic activity that could be stimulated by different cations. The expression of AsCAT1 protein in bacterial cells conferred tolerance to some abiotic stresses (NaCl, sorbitol, and LiCl). AsCAT1 is highly expressed in leaves, but its expression is low in roots as previously shown for other monocotyledonous plants. Interestingly, AsCAT1 gene expression is upregulated in response to a variety of stimuli, including hormonal, osmotic, salt, and heavy metal exposures. Our data strongly suggest that AsCAT1 is a crucial gene implicated in oat to aid this species in fending off environmental challenges. Such results help in further understanding the functions of catalase proteins in monocotyledonous plants in general and oat in particular.

Jasmonates are important plant hormones widely involved in processes such as plant growth and stress responses. However, the effects of jasmonic acid on the growth, development, and quality formation in carrots (Daucus carota L.) are less frequently reported. In this study, treatments of 100 µmol/L methyl jasmonate (MeJA), 200 µmol/L MeJA, and 10 mmol/L sodium diethyldithiocarbamate (DIECA) were established, with water serving as the control group, to investigate the effects of different concentrations of MeJA and its inhibitor DIECA on carrot growth and development, fleshy root structure, and the accumulation of lignin and carotenoids. Compared to the control, MeJA treatment significantly increased the number of xylem vessels in the carrot fleshy root, with thickened cell walls, enhanced lignin-related enzyme activities, and well-developed xylem. Different concentrations of MeJA promoted the accumulation of both lignin and carotenoids in carrots, whereas DIECA treatment did the opposite. Gene expression analysis indicated that MeJA altered the transcript levels of genes in carotenoid and lignin metabolism. The research findings in this paper would provide new insights into jasmonic acid-mediated carrot root development and quality formation.