Most land plants are symbiotic with arbuscular mycorrhizal fungi (AMF), which take up mineral nutrients from the soil and exchange them with plants for photosynthetically fixed carbon. This exchange ...is a significant factor in global nutrient cycles as well as in the ecology, evolution and physiology of plants. Despite its importance as a nutrient, very little is known about how AMF take up nitrogen and transfer it to their host plants. Here we report the results of stable isotope labelling experiments showing that inorganic nitrogen taken up by the fungus outside the roots is incorporated into amino acids, translocated from the extraradical to the intraradical mycelium as arginine, but transferred to the plant without carbon. Consistent with this mechanism, the genes of primary nitrogen assimilation are preferentially expressed in the extraradical tissues, whereas genes associated with arginine breakdown are more highly expressed in the intraradical mycelium. Strong changes in the expression of these genes in response to nitrogen availability and form also support the operation of this novel metabolic pathway in the arbuscular mycorrhizal symbiosis.
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DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this study, a novel, non-toxic, eco-friendly zinc oxide nanoparticles (ZnO-NPs) was used instead of the synthetic fungicides widely used to control the destructive phytopathogenic fungus
Fusarium ...oxysporum
, the causative agent of wilt disease in
Solanum melongena
L. Herein, the biosynthesized ZnO-NPs was carried out by
Penicillium expansum
ATCC 7861. In vitro, mycosynthesized ZnO-NPs exhibited antifungal activity against
Fusarium oxysporum
. In vivo, ZnO-NPs suppressed
Fusarium
wilt disease in cultivated
Solanum melongena
L. by decreasing the disease severity with 75% of plant protection. Moreover, ZnO-NPs stimulated the recovery of eggplant as an indicated by improving of morphological and metabolic indicators including plant height(152.5%), root length(106.6%), plant fresh biomass (146%), chlorophyll a (102.8%), chlorophyll b (67.86%), total soluble carbohydrates (48.5%), total soluble protein (81.8%), phenol (10.5%), antioxidant activity and isozymes compared with infected control
.
Therefore, this study suggests using mycosynthesized ZnO-NPs as an alternative to synthetic fungicides not only to eradicate the
Fusarium
wilt disease in cultivated eggplant (
Solanum melongena
) but also to promote the growth parameters and metabolic aspects.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Grain size is one of the key determinants of grain yield. Although a number of genes that control grain size in rice (
) have been identified, the overall regulatory networks behind this process ...remain poorly understood. Here, we report the map-based cloning and functional characterization of the quantitative trait locus
, which encodes a plant-specific plant AT-rich sequence- and zinc-binding transcription factor that regulates rice grain length and spikelet number.
positively controls grain length by promoting cell proliferation in young panicles and grains. The null
mutant possesses short grains, whereas overexpression of
results in large grains and decreased grain number per panicle. We demonstrate that GL6 participates in RNA polymerase III transcription machinery by interacting with RNA polymerase III subunit C53 and transcription factor class C1 to regulate the expression of genes involved in rice grain development. Our findings reveal a further player involved in the regulation of rice grain size that may be exploited in future rice breeding.
Chlorophyll fluorescence has been routinely used for many years to monitor the photosynthetic performance of plants non-invasively. The relationships between chlorophyll fluorescence parameters and ...leaf photosynthetic performance are reviewed in the context of applications of fluorescence measurements to screening programmes which seek to identify improved plant performance. The potential role of chlorophyll fluorescence imaging in increasing both the sensitivity and throughput of plant screening programmes is examined. Finally, consideration is given to possible specific applications of chlorophyll fluorescence for screening of plants for tolerance to environmental stresses and for improvements in glasshouse production and post-harvest handling of crops.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Starch serves functions that range over a timescale of minutes to years, according to the cell type from which it is derived. In guard cells, starch is rapidly mobilized by the synergistic action of ...β-AMYLASE1 (BAM1) and α-AMYLASE3 (AMY3) to promote stomatal opening. In the leaves, starch typically accumulates gradually during the day and is degraded at night by BAM3 to support heterotrophic metabolism. During osmotic stress, starch is degraded in the light by stress-activated BAM1 to release sugar and sugar-derived osmolytes. Here, we report that AMY3 is also involved in stress-induced starch degradation. Recently isolated Arabidopsis thaliana amy3 bam1 double mutants are hypersensitive to osmotic stress, showing impaired root growth. amy3 bam1 plants close their stomata under osmotic stress at similar rates as the wild type but fail to mobilize starch in the leaves. 14C labeling showed that amy3 bam1 plants have reduced carbon export to the root, affecting osmolyte accumulation and root growth during stress. Using genetic approaches, we further demonstrate that abscisic acid controls the activity of BAM1 and AMY3 in leaves under osmotic stress through the AREB/ABF-SnRK2 kinase-signaling pathway. We propose that differential regulation and isoform subfunctionalization define starch-adaptive plasticity, ensuring an optimal carbon supply for continued growth under an ever-changing environment.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Proanthocyanidins are oligomeric and polymeric end products of the flavonoid biosynthetic pathway. They are present in the fruits, bark, leaves and seeds of many plants, where they provide protection ...against predation. At the same time they give flavor and astringency to beverages such as wine, fruit juices and teas, and are increasingly recognized as having beneficial effects on human health. The presence of proanthocyanidins is also a major quality factor for forage crops. The past 2 years have seen important breakthroughs in our understanding of the biosynthesis of the building blocks of proanthocyanidins, the flavan-3-ols (+)-catechin and (-)-epicatechin. However, virtually nothing is known about the ways in which these units are assembled into the corresponding oligomers in vivo. Molecular genetic approaches are leading to an understanding of the regulatory genes that control proanthocyanidin biosynthesis, and this information, together with increased knowledge of the enzymes specific for the pathway, will facilitate the genetic engineering of plants for introduction of value-added nutraceutical and forage quality traits.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Aims
To investigate the effects of polystyrene microplastics (PS-beads) on the soil properties, photosynthesis of Flowering Chinese cabbage, the rhizosphere microbial community and their potential ...correlation in soil with different residues.
Methods
The influences of PS-beads (PS-MPs, M1, 5 μm; PS-NPs, M2, 70 nm) on the plant photosynthesis and growth parameters, soil dissolved organic matter (DOM) and the characteristic functional groups, the microbial community and metabolism prediction were studied by a pot-experiment in soil without residues (N), with biochar (B), degradable mulching film (DMF) fragments (D), or biochar and DMF (BD).
Key results
Chlorophyll a was more susceptible to the exogenous substances than Chlorophyll b. In soil with different residues, PS-beads of different sizes could change different components, structures and functional groups in aromatic rings of DOM, might further change the microbial community and metabolism. M2 decreased TDN and NO
3
−
and increased the weight of the plant in group D. M2 increased the weight of the plant in group N. M2 decreased the net photosynthetic rate in group B. The different sizes of PS-beads affected the different parameters of plant growth and potentially changed the plant growth and photosynthetic parameters through altering the microbial metabolism and the correlation among microbes. The potential mechanisms of PS-beads changing the plant growth were different in soil with different residues.
Conclusions
Our results evidenced the PS-beads potentially changed the plant growth and photosynthesis by changing the microbial metabolism and the correlation among microbes.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Drought is one of the greatest limitations to crop expansion outside the present-day agricultural areas. It will become increasingly important in regions of the globe where, in the past, the problem ...was negligible, due to the recognized changes in global climate. Today the concern is with improving cultural practices and crop genotypes for drought-prone areas; therefore, understanding the mechanisms behind drought resistance and the efficient use of water by the plants is fundamental for the achievement of those goals. In this paper, the major constraints to carbon assimilation and the metabolic regulations that play a role in plant responses to water deficits, acting in isolation or in conjunction with other stresses, is reviewed. The effects on carbon assimilation include increased resistance to diffusion by stomata and the mesophyll, as well as biochemical and photochemical adjustments. Oxidative stress is critical for crops that experience drought episodes. The role of detoxifying systems in preventing irreversible damage to photosynthetic machinery and of redox molecules as local or systemic signals is revised. Plant capacity to avoid or repair membrane damage during dehydration and rehydration processes is pivotal for the maintenance of membrane integrity, especially for those that embed functional proteins. Among such proteins are water transporters, whose role in the regulation of plant water status and transport of other metabolites is the subject of intense investigation. Long-distance chemical signalling, as an early response to drought, started to be unravelled more than a decade ago. The effects of those signals on carbon assimilation and partitioning of assimilates between reproductive and non-reproductive structures are revised and discussed in the context of novel management techniques. These applications are designed to combine increased crop water-use efficiency with sustained yield and improved quality of the products. Through an understanding of the mechanisms leading to successful adaptation to dehydration and rehydration, it has already been possible to identify key genes able to alter metabolism and increase plant tolerance to drought. An overview of the most important data on this topic, including engineering for osmotic adjustment or protection, water transporters, and C4 traits is presented in this paper. Emphasis is given to the most successful or promising cases of genetic engineering in crops, using functional or regulatory genes. as well as to promising technologies, such as the transfer of transcription factors.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Water status is the main factor affecting rice production. In order to understand rice strategies in response to drought condition in the field, the drought-responsive mechanisms at the physiological ...and molecular levels were studied in two rice genotypes with contrasting susceptibility to drought stress at reproductive stage. After 20d of drought treatment, the osmotic potential of leaves reduced 78% and 8% in drought susceptible rice cultivar Zhenshan97B and tolerant rice cultivar IRAT109, respectively. The panicle lengths had no obvious changes in drought stressed Zhenshan97B and IRAT109, suggesting that drought stress impose less effect on assimilate translocation from leaf to vegetative growth of panicles. IRAT109 showed more extensive deeper root growth that could be considered a second line of defense against drought stress. The Ci/Ca ratio exhibited enhancement over reduction of gs in both cultivars, reflecting the non-stomatal limitation to photosynthesis occurred during drought stress. Orthophosphate dikinase, glycine dehydrogenase, ribulose bisphosphate carboxylase (Rubisco), glycine hydroxymethyltransferase and ATP synthase were down-regulated for Zhenshan97B in response to drought stress, suggesting the reduction of capacity of carbon assimilation in this rice cultivar. In drought-stressed IRAT109, transketolase, Rubisco were down-regulated, however, Rubisco activase and peptidyl-prolyl cis–trans isomerase, which might alleviate the damage on Rubisco by drought stress, were up-regulated. The increased abundances of chloroplastic superoxide dismutase Cu–Zn and dehydroascorbate reductase might provide antioxidant protection for IRAT109 against damage by dehydration.
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GEOZS, IMTLJ, KILJ, KISLJ, NUK, OILJ, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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