1,720,982 research outputs found
Cucurbita pepo L. can be transformed by Agrobacterium rhizogenes.
No full textTwo-week-old in vitro grown Cucurbita pepo L. intact plants and cotyledons (detached and undetached from themother-plant) were transformed by Agrobacterium rhizogenes strain NCPPB 1855, grown for 48 h at 25 C onYMB medium. All infected material formed vigorous hairy roots in about seven days. The transformed roots weresuccessfully grown in liquid MS medium without plant growth regulators for an indefinite number of transfers.Genetic transformation of root DNA was proven by Southern analysis performed with a rolABC probe and a virprobe. Our results demonstrate that, in contrast with previous literature, A. rhizogenes could represent an efficientand reproducible system to transform C. pepo plants. Furthermore, we verified that plant age and incubationtimes/temperatures of bacterial strain influence transformation efficiency
Bryophytes: how to conquer an alien planet and live happily (ever after)
Full text linkThere are many push and pull factors that commonly drive individuals to leave their homeland. For example, escaping competition and occupying a novel habitat undoubtedly offer the advantage of new opportunities to pilgrims, but the absence of unfavorable biotic interactions can be counterbalanced by other antagonistic abiotic forces. After all, conquering an alien planet is not now nor ever was an easy task. We cannot know how many attempts and failures have punctuated the journey that led ancestral, photosynthetic organisms to leave the aquatic world and successfully establish on dry land. However, some traits developed by the ancestors of modern bryophytes that allowed them to adapt their life cycle to such a different habitat and persist there, have been undoubtedly identified
Responses of Arabidopsis thaliana seedlings in a Cd/Cu/Zn multi-pollution context
No full textSeedlings of A. thaliana were exposed to cadmium, copper and zinc at two different concentrations, supplied separately or in combinations. The amounts of these metals were measured in shoots and roots, and a significant competition in cadmium and copper/zinc root uptake was observed. Microscopic analyses revealed that the root morphology was affected by metal exposure, probably because the levels of trans-zeatin riboside, dehydrozeatin riboside, indol-3-acetic acid, and the auxin/cytokinins ratio varied significantly amongst the metal-treated plants. RT-PCR analysis of some genes involved in auxin and cytokinin synthesis showed an up-regulated transcription after exposure to metals. Not least, phytochelatins appeared to play a possible role in zinc/copper homeostasis, other than in cadmium detoxification
Biological responses to heavy metal stress in the moss Leptodictyum riparium (Hedw.) Warnst
Full text linkLeptodictyum riparium, a widely distributed aquatic moss, can both tolerate and accumulate very high concentrations of toxic heavy metals, with only slight apparent damage. Here we report the effects on photosynthetic yield, glutathione (GSH), phytochelatin (PCn) synthesis, nitrogen metabolism and cellular localization of molecules rich in SH groups in L. riparium exposed in vitro to heavy metals. We simulated the concentrations of Cu, Zn, Cd, Pb detected in Regi Lagni, Italy, one of the most contaminated freshwater sites in Southern Europe, in the laboratory to test how the moss responds to heavy metal contamination. There was a steady decrease of photosynthetic efficiency correlated with the heavy metal concentrations and ultrastructural organization. All PCn levels increased significantly as the concentration of heavy metals increased, while the GSH levels did not appear to be particularly affected. A significant increase of GDH and NADH-GOGAT activities increased with increasing heavy metal concentration. Immunoblotting analysis revealed an increase of the chl-GS2 while no significant increase was detected in the cyt-GS1. These results give insight into the molecular events underlying the metal-tolerance of the aquatic moss L. riparium exposed to environmental heavy metal concentrations
Evolution and functional differentiation of recently diverged phytochelatin synthase genes from Arundo donax L.
Full text linkPhytochelatin synthases (PCSs) play pivotal roles in the detoxification of heavy metals and metalloids in plants; however, little information on the evolution of recently duplicated PCS genes in plant species is available. Here we characterize the evolution and functional differentiation of three PCS genes from the giant reed (Arundo donax L.), a biomass/bioenergy crop with remarkable resistance to cadmium and other heavy metals. Phylogenetic reconstruction with PCS genes from fully sequenced monocotyledonous genomes indicated that the three A. donax PCSs, namely AdPCS1-3, form a monophyletic clade. The AdPCS1-3 genes were expressed at low levels in many A. donax organs and displayed different levels of cadmium-responsive expression in roots. Overexpression of AdPCS1-3 in Arabidopsis thaliana and yeast reproduced the phenotype of functional PCS genes. Mass spectrometry analyses confirmed that AdPCS1-3 are all functional enzymes, but with significant differences in the amount of the phytochelatins synthesized. Moreover, heterogeneous evolutionary rates characterized the AdPCS1-3 genes, indicative of relaxed natural selection. These results highlight the elevated functional differentiation of A. donax PCS genes from both a transcriptional and an enzymatic point of view, providing evidence of the high evolvability of PCS genes and of plant responsiveness to heavy metal stress
Tools for in vitro propagation/synchronization of the liverwort Marchantia polymorpha and application of a validated HPLC-ESI-MS-MS method for glutathione and phytochelatin analysis
Full text linkBryophytes, due to their poikilohydric nature and peculiar traits, are useful and versatile organisms for studies on metal accumulation and detoxification in plants. Among bryophytes, the liverwort Marchantia polymorpha is an excellent candidate as a model organism, having a key role in plant evolutionary history. In particular, M. polymorpha axenic cultivation of gametophytes offers several advantages, such as fast growth, easy propagation and high efficiency of crossing. Thus, the main purpose of this work was to promote and validate experimental procedures useful in the establishment of a standardized set-up of M. polymorpha gametophytes, as well as to study cadmium detoxification processes in terms of thiol-peptide production, detection and characterisation by HPLC-mass spectrometry. The results show how variations in the composition of the Murashige and Skoog medium impact the growth rate or development of this liverwort, and what levels of glutathione and phytochelatins are produced by gametophytes to counteract cadmium stress
Response of barley plants to Fe deficiency and Cd contamination as affected by S starvation
Full text linkBoth Fe deficiency and Cd exposure induce rapid changes in the S nutritional requirement of plants. The aim of this work was to characterize the strategies adopted by plants to cope with both Fe deficiency (release of phytosiderophores) and Cd contamination [production of glutathione (GSH) and phytochelatins] when grown under conditions of limited S supply. Experiments were performed in hydroponics, using barley plants grown under S sufficiency (1.2mM sulphate) and S deficiency (0mM sulphate), with or without Fe III-EDTA at 0.08mM for 11d and subsequently exposed to 0.05mM Cd for 24h or 72h. In S-sufficient plants, Fe deficiency enhanced both root and shoot Cd concentrations and increased GSH and phytochelatin levels. In S-deficient plants, Fe starvation caused a slight increase in Cd concentration, but this change was accompanied neither by an increase in GSH nor by an accumulation of phytochelatins. Release of phytosiderophores, only detectable in Fe-deficient plants, was strongly decreased by S deficiency and further reduced after Cd treatment. In roots Cd exposure increased the expression of the high affinity sulphate transporter gene (HvST1) regardless of the S supply, and the expression of the Fe deficiency-responsive genes, HvYS1 and HvIDS2, irrespective of Fe supply. In conclusion, adequate S availability is necessary to cope with Fe deficiency and Cd toxicity in barley plants. Moreover, it appears that in Fe-deficient plants grown in the presence of Cd with limited S supply, sulphur may be preferentially employed in the pathway for biosynthesis of phytosiderophores, rather than for phytochelatin production
Phytochelatin synthase de-regulation in Marchantia polymorpha indicates cadmium detoxification as its primary ancestral function in land plants and provides a novel visual bioindicator for detection of this metal
Full text linkBy genetic transformation and genome editing, in this study we obtained lines of the model bryophyte
Marchantia polymorpha with de-regulated activity of the phytochelatin synthase (MpPCS) enzyme, responsible for
the biosynthesis of metal(loid) chelators phytochelatins (PCn). Lack of PCn causes hypersensitivity to cadmium
but has only subtle effects on sensitivity to excess of other highly toxic metals and the metalloid arsenic in
M. polymorpha. Besides, our results indicate that MpPCS has a minor role in the maintenance of essential metals
like zinc.
As liverworts are sister to tracheophytes, these results suggest that the primary ancestral function of PCS genes
in the common ancestor of all land plants may have been the detoxification of the non-essential cadmium ion.
Hypersensitivity to cadmium further suggests that the Mppcs mutants could become useful bioindicators to
specifically detect environmental contaminations of cadmium through direct visual assessment of plant growth
and pigmentation
ANTIFUNGAL ACTIVITY OF DIKETOPIPERAZINES EXTRACTED FROM ALTERNARIA ALTERNATA AGAINST PLASMOPARA VITICOLA: AN ULTRASTRUCTURAL STUDY
No full textThree dipeptides, belonging to the family of diketopiperazines (DKPs), were extracted from broth culture of the grapevine endophyte Alternaria alternata, and were tested against Plasmopara viticola on leaves of grapevine plants grown in greenhouse. DKPs, used at different concentrations (10(-3), 10(-4), 10(-5) and 10(-6)M) both singularly and in mixtures, demonstrated real effectiveness in inhibiting P. viticola sporulation when applied 2 or 24h after pathogen inoculation. Moreover, no necrotic lesions or other phytotoxicity symptoms were observed on DKP-treated grapevine leaf tissues. Ultrastructural analysis performed on grapevine leaf tissues revealed that the DKPs used singularly and in mixture, at above reported concentrations, did not cause leaf tissue damages. By contrast, hyphae of P. viticola exhibited marked structural changes, similar to those induced by the endophyte A. alternata. This demonstrates the involvement of these metabolites in the relationship of P. viticola and the endophyte. Further experimental trials will be carried out in the next future in order to test the effectiveness of these molecules also under field conditions, and to better understand the mechanism of action involved in the pathogen inhibition
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