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71.
Aims: To optimize the medium components for the production of indole‐3‐acetic acid (IAA) by isolated bacterium Pantoea agglomerans strain PVM. Methods and Results: Present study deals with the production of an essential plant hormone IAA by a bacterial isolate P. agglomerans strain PVM identified by 16S rRNA gene sequence analysis. The medium containing 8 g l?1 of meat extract and 1 g l?1 of l ‐tryptophan (precursor) at optimum pH 7, 30°C and 48‐h incubation gave the maximum production of IAA (2·191 g l?1). Effect of IAA synthesized on in vitro root induction in Nicotiana tobacum (leaf) explants was compared with that of control. IAA was characterized by high‐performance thin‐layer chromatography, high‐performance liquid chromatography and gas chromatography–mass spectroscopy. Conclusions: Pantoea agglomerans strain PVM was a good candidate for the inexpensive and utmost production of IAA in short period, as it requires simple medium (meat extract and l ‐tryptophan). Significance and Impact of the Study: The present report first time showed the rapid, cost‐effective and maximum production of IAA. No reports are available on the optimization of particular medium components for the production of IAA. This study demonstrates a novel approach for in vitro root induction in N. tobacum (leaf) explants. 相似文献
72.
Studies of abscisic acid (ABA) and auxin have revealed that these pathways impinge on each other. The Daucus carota (L.) Dc3 promoter: uidA (-glucuronidase: GUS) chimaeric reporter (ProDc3:GUS) is induced by ABA, osmoticum, and the auxin indole-3-acetic acid (IAA) in vegetative tissues of transgenic Arabidopsis thaliana (L.) Heynh. Here, we describe the root tissue-specific expression of ProDc3:GUS in the ABA-insensitive-2 (abi2-1), auxin-insensitive-1 (aux1), auxin-resistant-4 (axr4), and rooty (rty1) mutants of Arabidopsis in response to ABA, IAA and synthetic auxins naphthalene acetic acid (NAA), and 2, 4-(dichlorophenoxy) acetic acid. Quantitative analysis of ProDc3:GUS expression showed that the abi2-1 mutant had reduced GUS activity in response to ABA, IAA, or 2, 4-d, but not to NAA. Similarly, chromogenic staining of ProDc3:GUS activity showed that the aux1 and axr4 mutants gave predictable hypomorphic ProDc3:GUS expression phenotypes in roots treated with IAA or 2, 4-d, but not the diffusible auxin NAA. Likewise the rty mutant, which accumulates auxin, showed elevated ProDc3:GUS expression in the absence or presence of hormones relative to wild type. Interestingly, the aux1 and axr4 mutants showed a hypomorphic effect on ABA-inducible ProDc3:GUS expression, demonstrating that ABA and IAA signaling pathways interact in roots. Possible mechanisms of crosstalk between ABA and auxin signaling are discussed. 相似文献
73.
Gravitropism is explained by the Cholodny–Went hypothesis: the basipetal flow of auxin is diverted laterally. The resulting
lateral auxin gradient triggers asymmetric growth. However, the Cholodny–Went hypothesis has been questioned repeatedly because
the internal auxin gradient is too small to account for the observed growth asymmetry. Therefore, an additional gradient in
indolyl-3-acetic acid (IAA) sensitivity has been suggested (Brauner and Hager in Planta 51:115–147, 1958). We challenged the
Cholodny–Went hypothesis for gravitropism of rice coleoptiles (Oryza sativa L.) and found it to be essentially true. However, we observed, additionally, that the two halves of gravitropically stimulated
coleoptiles responded differentially to the same amount of exogenous auxin: the auxin response is reduced in the upper flank
but normal in the lower flank. This indicates that the auxin-gradient is amplified by a gradient of auxin responsiveness.
Hormone contents were measured across the coleoptile by a GC-MS/MS technique and a gradient of jasmonate was detected opposing
the auxin gradient. Furthermore, the total content of jasmonate increased during the gravitropic response. Jasmonate gradient
and increase persist even when the lateral IAA gradient is inhibited by 1-N-naphtylphtalamic acid. Flooding with jasmonate delays the onset of gravitropic bending. Moreover, a jasmonate-deficient rice
mutant bends more slowly and later than the wild type. We discuss a role of jasmonate as modulator of auxin responsiveness
in gravitropism. 相似文献
74.
Immunohistochemical localization of IAA and ABP1 in strawberry shoot apexes during floral induction 总被引:6,自引:0,他引:6
By using an anti-indole-acetic acid (anti-IAA) monoclonal antibody and an anti-auxin-binding protein 1 (anti-ABP1) polyclonal
antibody, IAA and ABP1 were immunohistochemically localized in strawberry (Fragaria ananassa Duch.) shoot apexes during floral induction. The spatial distribution patterns of endogenous IAA and ABP1 and their dynamic
changes during floral induction were investigated. In addition, the affect of 1-N-naphthylphtalamic acid (NPA) on IAA distribution during floral induction was also analyzed. The results showed that IAA was
present in the shoot apexes throughout the floral induction process, gradually concentrating in the shoot apical meristem
(SAM). The distribution of ABP1 and its dynamic changes were similar to those of IAA. In addition, the ABP1 immune signal
in SAM gradually increased as floral induction developed. On a morphological level, these results indicate both the spatial
distribution and dynamic changes in endogenous IAA and ABP1 during the floral induction process. The close correlation found
between IAA and ABP1 indicates that a cooperation occurs during the regulation of floral induction. The results also suggest
that IAA was the significant agent for floral induction, and that SAM might be the place of the main action. Treatment with
NPA during floral induction prevented the accumulation of IAA in the SAM, delayed the process of floral differentiation and
induced an abnormal flower development. It is likely that IAA in the shoot apex is produced in young leaves and transported
through the vascular tissues to the SAM and other places of function. Finally, an appropriate amount of IAA in the SAM and
normal polar auxin transport are essential for floral induction and differentiation in strawberries. 相似文献
75.
Hasegawa G Kikuchi M Kobayashi Y Saito Y 《Journal of biochemical and biophysical methods》2005,63(1):33-42
We have synthesized a novel reagent containing dansyl group, iodoacethyl dansylcadaverine (IADC), which specifically alkylates sulfhydryl groups. The carboxyl group of iodoacetic acid was activated with dicyclohexylcarbodiimide and was condensed with amino group of dansylcadaverine. Purity and chemical structure of IADC was confirmed with mass spectrometry (MS) and NMR. IADC alkylated GSH but not GSSG, which was confirmed by MS. The reactivity of IADC with proteins was also investigated with Western blotting using anti-dansyl antibody. IADC reacted only with sulfhydryl-containing proteins. The specificity of the interaction of IADC with sulfhydryl groups in proteins was confirmed by adding excessive amount of a well-known sulfhydryl-specific reagent, 5, 5'-dithiobis(2-nitrobenzoic acid), which led to a complete inhibition. To show the usefulness of IADC, the cysteines in glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from chicken muscle were modified with this reagent, and GAPDH was then digested by lysyl endopeptidase. The peptides generated from digestion of IADC-incorporated GAPDH were applied to an anti-dansyl immunoaffinity column. The peptide fragments bound and eluted from the column were separated by HPLC, and the amino acid sequence of each peptide was analyzed, and peptide was identified as the one containing a Cys residue(s). These data showed that IADC is a useful reagent to specifically identify the positions of a Cys residue(s) in proteins. 相似文献
76.
Navarro-Aviñó JP Bennett AB 《Biochemical and biophysical research communications》2005,329(1):406-415
The control of the Ca(2+)-ATPase gene (LCA1) that encodes two different membrane-located isoforms by two antagonic phytohormones, ABA and IAA, has been investigated. Strikingly both the growth regulators induce the LCA1 expression. By using a protoplast transient system, the cis-acting DNA elements responding to both, abiotic stress (ABA) and normal development (IAA), are dissected. ABA triggered a 4-fold increase in the GUS-activity. A single ACGT motif responsible for most of the LCA1 mRNA induction was localized at an unexpectedly large distance (1577 bp) upstream of the translational start. In the case of IAA, although there is a TGTCTC sequence that is known to be an important cis-acting element, two TGA motifs play a more critical role. It is proposed that the Ca(2+)-ATPase isoforms might intervene in the generation of specific Ca(2+) signals by restoring steady-state Ca(2+) levels, modulating both frequency and amplitude of Ca(2+) waves via wave interference. 相似文献
77.
Auxin-induced reactive oxygen species production requires the activation of phosphatidylinositol 3-kinase 总被引:10,自引:0,他引:10
We recently reported that production of reactive oxygen species (ROS) is essential for auxin-induced gravitropic signaling. Here, we investigated the role of phosphatidylinositol 3-kinase and its product, PtdIns(3)P, in auxin-mediated ROS production and the root gravitropic response. Pretreatment with LY294002, an inhibitor of PtdIns 3-kinase activity, blocked auxin-mediated ROS generation, and reduced the sensitivity of root tissue to gravistimulation. The amount of PtdIns(3)P increased in response to auxin, and this effect was abolished by pretreatment with LY294002. In addition, sequestration of PtdIns(3)P by transient expression of the endosome binding domain in protoplasts abrogated IAA-induced ROS accumulation. These results indicate that activation of PtdIns 3-kinase and its product PtdIns(3)P are required for auxin-induced production of ROS and root gravitropism. 相似文献
78.
MDR-like ABC transporter AtPGP4 is involved in auxin-mediated lateral root and root hair development 总被引:17,自引:0,他引:17
Santelia D Vincenzetti V Azzarello E Bovet L Fukao Y Düchtig P Mancuso S Martinoia E Geisler M 《FEBS letters》2005,579(24):5399-5406
Previous data have suggested an involvement of MDR/PGP-like ABC transporters in transport of the plant hormone auxin and, recently, AtPGP1 has been demonstrated to catalyze the primary active export of auxin. Here we show that related isoform AtPGP4 is expressed predominantly during early root development. AtPGP4 loss-of-function plants reveal enhanced lateral root initiation and root hair lengths both known to be under the control of auxin. Further, atpgp4 plants show altered sensitivities toward auxin and the auxin transport inhibitor, NPA. Finally, mutant roots reveal elevated free auxin levels and reduced auxin transport capacities. These results together with yeast growth assays suggest a direct involvement of AtPGP4 in auxin transport processes controlling lateral root and root hair development. 相似文献
79.
Oligopeptidase B (OpdB) from Trypanosoma brucei is a candidate therapeutic target in African trypanosomiasis. OpdB is an atypical serine peptidase, since activity is inhibited by thiol-blocking reagents and enhanced by reducing agents. We have identified C256 as the reactive cysteine residue that mediates OpdB inhibition by N-ethylmaleimide and iodoacetic acid. Modeling studies suggest that C256 adducts occlude the P(1) substrate-binding site, preventing substrate binding. We further demonstrate that C559 and C597 are responsible for the thiol-enhancement of OpdB activity. These studies may facilitate the development of specific OpdB inhibitors with therapeutic potential, by exploiting these unique properties of this enzyme. 相似文献
80.
R Morgenstern J W DePierre L Ernster 《Biochemical and biophysical research communications》1979,87(3):657-663
Rat liver microsomes exhibit glutathione S-transferase activity with 1-chloro-2,4-dinitrobenzene as the second substrate. This activity can be stimulated 8-fold by treatment of the microsomes with N-ethylmaleimide and 4-fold with iodoacetamide. The corresponding glutathione S-transferase activity of the supernatant fraction is not affected by such treatment. These findings suggest that rat liver microsomes contain glutathione S-transferase distinct from those found in the cytoplasmic and that the microsomal transferase can be activated by modification of microsomal sulfhydryl group(s). 相似文献