1,721,032 research outputs found
Dataset for mPhil thesis - The role of chloroplasts in responding to drought stress in plants
No full textThe dataset relating to the mPhil thesis of Matthew Alan Woodard
The dataset includes 8 zipped folders with the following titles:
- HO1-OX NF screens and gene expression
- HO1-OX lines Chlorophyll and protochlorophyllide data
- FC2 overexpressing lines
- FC lines large drought experiment (FC1 and FC2)
- Drought photos for the large drought experiment
- N and Q drought lines single plants
- N and Q drought lines single plants photos continued
- 5hr Water Loss test
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The role of tetrapyrroles in chloroplast-to-nucleus retrograde signaling
No full textChloroplasts contain their own genomes and therefore chloroplast biogenesis requires the coordination of both chloroplast and nuclear gene expression. This is achieved by the exchange of signals between the two organelles. The existence of signals from the chloroplast (chloroplast-to-nucleus retrograde signaling) can be demonstrated by inhibition of chloroplast development through mutation or chemical treatment. This chloroplast damage results in the reduced expression of hundreds of nuclear-encoded genes, including many encoding chloroplast proteins. A classic mutant screen in which nuclear gene expression was retained after chloroplast damage resulted in the isolation of a series of genomes uncoupled or gun mutants. In five out of six mutants, the mutations resided in components of the tetrapyrrole biosynthesis pathway, resulting in a number of different models for the role of tetrapyrroles as retrograde signals. The current model is that a positive retrograde signal is generated by the activity of the ferrochelatase 1 enzyme suggesting that haem or a product of haem is a signal. The evidence for such a model and the interaction of tetrapyrrole signals with other possible retrograde signals is discussed. In addition, tetrapyrroles can generate singlet oxygen on exposure to light and oxygen and there is accumulating evidence that a tetrapyrrole-derived, singlet oxygen-dependent retrograde signal is important during chloroplast biogenesis and for stress signaling from mature chloroplasts.</p
Purification of wheat leaf plasma membranes and characterization of plasma membrane atpase activity and phytochrome binding
No full textSIGLEAvailable from British Library Document Supply Centre- DSC:DX97099 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
FIGURES 9–11. Zorotypus novobritannicus n in Zorotypus novobritannicus n. sp., the first species of the order Zoraptera (Zorotypidae) from the Australasian Ecozone
No full textFIGURES 9–11. Zorotypus novobritannicus n. sp., female. 9) Female abdomen and cerci, dorsal view. 10) Posterior tip of female abdomen, ventral view. 11) Terminal abdominal sclerites and cerci, posterior view.Published as part of Terry, Matthew D. & Whiting, Michael F., 2012, Zorotypus novobritannicus n. sp., the first species of the order Zoraptera (Zorotypidae) from the Australasian Ecozone, pp. 53-61 in Zootaxa 3260 on page 56, DOI: 10.5281/zenodo.21542
The aurea and yellow-green-2 mutants of tomato are deficient in phytochrome chromophore synthesis
No full textThe phytochrome-deficient aurea mutant of tomato has been widely used for the study of both phytochrome function and the role of other photoreceptors in the control of development in higher plants. To date the exact nature of the aurea mutation has remained unknown, though this information is clearly important for the interpretation of these studies. It has been proposed that aurea and yellow-green-2, another mutant of tomato that has a similar phenotype to aurea, could be deficient in phytochrome chromophore synthesis. We have examined this hypothesis by measuring the activity of the enzymes committed to phytochrome chromophore synthesis in these mutants. The approach takes advantage of a recently developed high pressure liquid chromatography-based assay for the synthesis of the free phytochrome chromophore, phytochromobilin from its immediate precursors biliverdin IX? and heme. Isolated etioplasts from aurea and yellow-green-2 seedlings were specifically unable to convert biliverdin IX? to 3Z-phytochromobilin and heme to biliverdin IX?, respectively. In addition, the level of total noncovalently bound heme in the mutants was the same as in wild type seedlings. Together, these results identify both aurea and yellow-green-2 as mutants that are deficient in phytochrome chromophore synthesis. <br/
The nuclear genes Lhcb and HEMA1 are differentially sensitive to plastid signals and suggest distinct roles for the GUN1 and GUN5 plastid-signalling pathways during de-etiolation
No full textFeedback mechanisms are critical to the regulation of chloroplast development and signals from functional plastids are required to maintain nuclear gene expression of chloroplast proteins. To understand the role of these signals in de-etiolating Arabidopsis thaliana L. seedlings, we followed the expression of three nuclear genes, Lhcb, HEMA1 and GSA, under a variety of treatments (Norflurazon, lincomycin and a far-red light pretreatment) leading to plastid damage in white light and in a range of genetic backgrounds known to modulate plastid signalling: the genomes uncoupled mutants, gun1, gun4, gun5 and the gun1,5 double mutant, and in a transgenic line over-expressing NADPH:protochlorophyllide oxidoreductase. The three nuclear genes were differentially sensitive to changes in plastid signalling, with Lhcb the most strongly repressed and GSA insensitive to all but the most severe treatments. Analysis of plastid morphology in seedlings grown under identical conditions demonstrated that these responses corresponded closely to the degree of plastid damage. Furthermore, although Lhcb and HEMA1 were responsive to both GUN1 and GUN5 signals, the relative inputs from these pathways differed for each transcript with GUN1 being dominant for HEMA1 regulation. Further analysis of HEMA1 expression in gun1 seedlings under non-photobleaching conditions indicates that GUN1 is an important suppressor of HEMA1 expression in the dark and under saturating white light. These results are consistent with plastid signals functioning in a feedback regulatory mechanism during chloroplast biogenesis, and suggest a key role for GUN1 during the early stages of chloroplast development
Loss of nuclear gene expression during the phytochrome A-mediated far-red block of greening response
Full text linkWe have examined the expression of the HEMA1 gene, which encodes the key chlorophyll synthesis enzyme glutamyl-tRNA reductase, during the phytochrome A-mediated far-red light (FR) block of greening response in Arabidopsis. Our results demonstrate that the FR block of greening comprises two separate responses: a white light (WL) intensity-independent response that requires 3 d of FR and is associated with a loss of expression of the nuclear genes HEMA1 and Lhcb following the transfer to WL (transcriptionally coupled response) and a WL intensity-dependent response that is induced by 1 d of FR and is transcriptionally uncoupled. Both responses required phytochrome A. The transcriptionally uncoupled response correlated with a deregulation of tetrapyrrole synthesis and potential photooxidative damage and was inhibited by cytokinin. The transcriptionally coupled FR response was additive with the loss of expression following Norflurazon-induced photobleaching and was absent in the presence of sucrose or after lower fluence rate (1 µmol m2 s1) FR treatments. Both pathways leading to the loss of nuclear gene expression were inhibited by overexpression of NADPH:protochlorophyllide oxidoreductase, indicating a role for plastid signaling in the FR-mediated pathway. The significance of identifying a distinct phytochrome A-mediated plastid signaling pathway is discussed
Light signalling pathways regulating the Mg-chelatase branchpoint of chlorophyll synthesis during de-etiolation in arabidopsis thaliana
No full textPrecise regulation of tetrapyrrole synthesis is critical for plant survival when seedlings first emerge into the light. At this time there is a massive increase in demand for chlorophyll to drive the assembly of the photosynthetic apparatus. To understand how this demand is met we have followed the expression of genes encoding the chelatase enzymes at the branchpoint between chlorophyll and heme synthesis. Dark-grown Arabidopsis thaliana seedlings were transferred to continuous white, red, far-red or blue light and the expression of eight tetrapyrrole pathway genes was followed using real-time RT-PCR. Our results show that the CHLH gene encoding the H subunit of Mg-chelatase was induced by light under all conditions with an initial peak after 2-4 h light. The other Mg-chelatase subunit genes CHLI and CHLD and the ferrochelatase genes FC1 and FC2 were not strongly regulated at the level of transcript abundance, but the Mg-chelatase regulator GUN4 had an expression profile almost identical to that observed for CHLH. The CHLM gene encoding Mg-protoporphyrin IX methyltransferase, the next enzyme in the pathway, was also light regulated, but showed a very different pattern of expression. Using photoreceptor mutants it was demonstrated that regulation of CHLH and GUN4 is primarily under the control of phytochromes A and B with some input from the cryptochromes. Induction of CHLH and GUN4 under red and far-red light was also compromised in the phytochrome-signalling mutants, fhy1 and fhy3. These results establish GUN4 as a major target of photoreceptor regulation during the earliest stages of de-etiolation
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