Plant Hormone Indoleacetic Acid Research Articles

Modulating Wine Aromatic Amino Acid Catabolites by Using Torulaspora delbrueckii in Sequentially Inoculated Fermentations or Saccharomyces cerevisiae Alone.

Yeasts are the key microorganisms that transform grape juice into wine, and nitrogen is an essential nutrient able to affect yeast cell growth, fermentation kinetics and wine quality. In this work, we focused on the intra- and extracellular metabolomic changes of three aromatic amino acids (tryptophan, tyrosine, and phenylalanine) during alcoholic fermentation of two grape musts by two Saccharomyces cerevisiae strains and the sequential inoculation of Torulaspora delbrueckii with Saccharomyces cerevisiae. An UPLC-MS/MS method was used to monitor 33 metabolites, and 26 of them were detected in the extracellular samples and 8 were detected in the intracellular ones. The results indicate that the most intensive metabolomic changes occurred during the logarithm cellular growth phase and that pure S. cerevisiae fermentations produced higher amounts of N-acetyl derivatives of tryptophan and tyrosine and the off-odour molecule 2-aminoacetophenone. The sequentially inoculated fermentations showed a slower evolution and a higher production of metabolites linked to the well-known plant hormone indole acetic acid (auxin). Finally, the production of sulfonated tryptophol during must fermentation was confirmed, which also may explain the bitter taste of wines produced by Torulaspora delbrueckii co-fermentations, while sulfonated indole carboxylic acid was detected for the first time in such an experimental design.

ECHIDNA-mediated post-Golgi trafficking of auxin carriers for differential cell elongation

The plant hormone indole-acetic acid (auxin) is essential for many aspects of plant development. Auxin-mediated growth regulation typically involves the establishment of an auxin concentration gradient mediated by polarly localized auxin transporters. The localization of auxin carriers and their amount at the plasma membrane are controlled by membrane trafficking processes such as secretion, endocytosis, and recycling. In contrast to endocytosis or recycling, how the secretory pathway mediates the localization of auxin carriers is not well understood. In this study we have used the differential cell elongation process during apical hook development to elucidate the mechanisms underlying the post-Golgi trafficking of auxin carriers in Arabidopsis. We show that differential cell elongation during apical hook development is defective in Arabidopsis mutant echidna (ech). ECH protein is required for the trans-Golgi network (TGN)-mediated trafficking of the auxin influx carrier AUX1 to the plasma membrane. In contrast, ech mutation only marginally perturbs the trafficking of the highly related auxin influx carrier LIKE-AUX1-3 or the auxin efflux carrier PIN-FORMED-3, both also involved in hook development. Electron tomography reveals that the trafficking defects in ech mutant are associated with the perturbation of secretory vesicle genesis from the TGN. Our results identify differential mechanisms for the post-Golgi trafficking of de novo-synthesized auxin carriers to plasma membrane from the TGN and reveal how trafficking of auxin influx carriers mediates the control of differential cell elongation in apical hook development.

Genomes and Virulence Factors of Novel Bacterial Pathogens Causing Bleaching Disease in the Marine Red Alga Delisea pulchra

Nautella sp. R11, a member of the marine Roseobacter clade, causes a bleaching disease in the temperate-marine red macroalga, Delisea pulchra. To begin to elucidate the molecular mechanisms underpinning the ability of Nautella sp. R11 to colonize, invade and induce bleaching of D. pulchra, we sequenced and analyzed its genome. The genome encodes several factors such as adhesion mechanisms, systems for the transport of algal metabolites, enzymes that confer resistance to oxidative stress, cytolysins, and global regulatory mechanisms that may allow for the switch of Nautella sp. R11 to a pathogenic lifestyle. Many virulence effectors common in phytopathogenic bacteria are also found in the R11 genome, such as the plant hormone indole acetic acid, cellulose fibrils, succinoglycan and nodulation protein L. Comparative genomics with non-pathogenic Roseobacter strains and a newly identified pathogen, Phaeobacter sp. LSS9, revealed a patchy distribution of putative virulence factors in all genomes, but also led to the identification of a quorum sensing (QS) dependent transcriptional regulator that was unique to pathogenic Roseobacter strains. This observation supports the model that a combination of virulence factors and QS-dependent regulatory mechanisms enables indigenous members of the host alga's epiphytic microbial community to switch to a pathogenic lifestyle, especially under environmental conditions when innate host defence mechanisms are compromised.

The plant hormone indoleacetic acid induces invasive growth in Saccharomyces cerevisiae

Fungi must recognize plant-specific signals to initiate subsequent morphogenetic events such as filamentation that lead to infection. Here we show that the plant hormone indoleacetic acid (IAA) induces adhesion and filamentation of Saccharomyces cerevisiae. Genome expression profiling of cells treated with IAA identified Yap1, a fungal specific transcription factor, as a key mediator of this response. Strains lacking YAP1 (yap1-1) are hypersensitive to growth on IAA because they accumulate more IAA than can wild type. Members of a family of transporters the amino acid/auxin:proton symport permeases with homology to AUX1, a putative IAA transporter from plants, are up-regulated in the yap1-1 mutant. Deletion of any one of these transporters makes yap1-1 mutants more resistant to IAA by decreasing its uptake. The permease mutants are defective in IAA perception and filamentation. The ability of a fungus to perceive a plant hormone that causes it to differentiate into an invasive form has important implications for plant-pathogen interactions.

Synthesis of new indolecarboxylic acids related to the plant hormone indoleacetic acid IAA

The synthesis of 5,6-methylenedioxy-indol-3-yl-methanoic acid 8 and 5,6-methylenedioxy-indol-3-yl-acetic acid 13 is described. Piperonal was employed as starting material, and the construction of the heterocyclic ring based on the Hemetsberger reaction of the corresponding beta-azidostyrene was highly regiospecific. Compound 8 was obtained as a key intermediate towards 13, and a Mannich reaction was used to introduce the required alkyl side chain. The route comprised eight steps giving 13 in 26% overall yield. The formation of the indolic ring via reductive cyclisation of o,beta-dinitrostyrene is also presented.

All We Are Saying Is Give Plants a Chance!

This article has no abstract.

Biochemical characterization of recombinant polypeptides corresponding to the predicted βαα fold in Aux/IAA proteins

The plant hormone indoleacetic acid (IAA or auxin) transcriptionally activates a select set of early genes. The Auxl IAA class of early auxin-responsive genes encodes a large family of short-lived, nuclear proteins. Aux/IAA polypeptides homo-and heterodimerize, and interact with auxin-response transcription factors (ARFs) via C-terminal regions conserved in both protein families. This shared region contains a predicted βαα motif similar to the prokaryotic β-Ribbon DNA binding domain, which mediates both protein dimerization and DNA recognition. Here, we show by circular dichroism spectroscopy and by chemical cross-linking experiments that recombinant peptides corresponding to the predicted βαα region of three Aux/IAA proteins from Arabidopsis thaliana contain substantial α-helical secondary structure and undergo homo- and heterotypic interactions in vitro. Our results indicate a similar biochemical function of the plant βαα domain and suggest that the βαα fold plays an important role in mediating combinatorial interactions of Aux/IAA and ARF proteins to specifically regulate secondary gene expression in response to auxin.

Altered Growth and Wood Characteristics in Transgenic Hybrid Aspen Expressing Agrobacterium tumefaciens T-DNA Indoleacetic Acid-Biosynthetic Genes.

A key regulator of cambial growth is the plant hormone indoleacetic acid (IAA). Here we report on altered wood characteristics and growth patterns in transgenic hybrid aspen (Populus tremula L. x Populus tremuloides Michx.) expressing Agrobacterium tumefaciens T-DNA IAA-biosynthetic iaaM and iaaH genes. Eighteen lines simultaneously expressing both genes were regenerated. Of these, four lines, verified to be transgenic by northern blot analysis, were selected and raised under controlled growth conditions. All four lines were affected in their growth patterns, including alterations in height and stem diameter growth, internode elongation, leaf enlargement, and degree of apical dominance. Two transgenic lines, showing the most distinct phenotypic deviation from the wild type, were characterized in more detail for free and conjugated IAA levels and for wood characteristics. Both lines showed an altered IAA balance, particularly in mature leaves and roots where IAA levels were elevated. They also exhibited changes in wood anatomy, most notably a reduction in vessel size, an increase in vessel density, and changes in ray development. Thus, the recent development of techniques for gene transfer to forest trees enabled us to investigate the influence of an altered IAA balance on xylem development in an intact experimental system. In addition, the results demonstrate the possibility of manipulating wood properties in a forest tree through controlled changes of IAA concentration and distribution.

Induction kinetics of the nuclear proteins encoded by the early indoleacetic acid-inducible genes, PS-IAA4/5 and PS-IAA6, in pea (Pisum sativum L.).

The plant hormone indoleacetic acid (IAA) rapidly induces transcription of two genes, PS-IAA4/5 and PS-IAA6, in pea that encode nuclear proteins. The proteins were expressed in Escherichia coli and polyclonal antibodies were raised. The proteins can neither be detected on immunoblots of pea extracts from IAA-treated epicotyls nor subcellularly localized by immunofluorescence, suggesting that they are of low abundance. However, they can be immunoprecipitated as 35S-methionine-labeled proteins synthesized in vivo from control and IAA-treated tissue segments. Short-term time-course experiments indicate that the amounts of PS-IAA4/5 and PS-IAA6 proteins decrease dramatically in non-IAA-treated tissue. However, the hormone slightly increases the PS-IAA4/5 and significantly enhances the PS-IAA6 proteins compared with the initial amounts present in the tissue, despite a large induction of both mRNAs. A net increase in the amount of the in vivo synthesized PS-IAA6 is observed after a lag period of 30 min after addition of IAA. Little or no PS-IAA4/5 or PS-IAA6 protein is detected after 6 h of induction, even though PS-IAA4/5 and PS-IAA6 mRNAs remain detectable. Immunoprecipitation of in vitro translated polypeptides with mRNAs from various auxin-treated and untreated mono- and dicotyledonous plants reveals that similar proteins are encoded by constitutive or IAA-induced mRNAs. Phylogenetic analysis of 10 PS-IAA4-like proteins from various plant species reveals that the PS-IAA4 and PS-IAA6 proteins belong to different lineages, suggesting that they may have distinct functions. The data suggest that as a primary response to IAA plant tissues produce short-lived nuclear proteins whose synthesis is regulated at the transcriptional and post-transcriptional levels.

The Transport of Indole-3-Acetic Acid in Boron- and Calcium-Deficient Sunflower Hypocotyl Segments

Transfer of sunflower (Helianthus annuus L. cv Russian Mammoth) seedlings from complete nutrient solution to solutions deficient in either boron or calcium resulted in a steady decline in the rate of auxin transport, compared to seedlings that remained in the complete solution. In seedlings transferred to solutions deficient in both B and Ca, the decline in auxin transport was greater than seedlings deficient in only one element. The transfer of B- or Ca-deficient seedlings back to the complete solution prevented further decline in auxin transport, but auxin transport did not increase to the same level as seedlings maintained in complete solution. The significant reduction in auxin transport during the early stages of B or Ca deficiency was not related to (a) reduced growth rate of the hypocotyl, (b) increased acropetal movement of auxin, or (c) lack of respiratory substrates in the hypocotyl. In addition, no difference was found in the water-extractable total and ionic Ca in B-deficient and control nondeficient hypocotyls, indicating a direct effect of B on auxin transport, rather than indirectly by affecting Ca absorption. The rate of auxin transport in hypocotyls deficient in either B or Ca, was inversely correlated with K(+) leakage and rate of respiration. The data presented strongly support the view that there are separate sites for B and Ca in the basipetal transport of the plant hormone indoleacetic acid.

A new source of carbon oxides in biochemical systems. Implications regarding dioxetane intermediates

The peroxidase catalyzed aerobic oxidation of aromatic pyruvates produces the aromatic aldehyde, oxalate, CO and CO 2 and a weak light emission. This indicates the preliminary formation of a peroxy anion which can cyclizes to a four-membered ring dioxetane and to a five membered ring α-keto-β-peroxylactone intermediates. The possible importance of this new source of carbon oxides in biological systems is pointed out. The results considerably strengthen the view that a dioxetane is formed in side chain of the plant hormone indoleacetic acid during the oxidation catalyzed by peroxidase.

A receptor protein for indoleacetic acid from plant chromatin and its role in transcription

A high affinity, low capacity binding protein for the plant hormone indole acetic acid has been isolated from the non-histone chromosomal proteins of coconut ( Coccos nucifera ) endosperm cells. The protein appears to be homogeneous in native and denaturing conditions in polyacrylamide gel electrophoresis and has a molecular weight 70,000 dalton. A role as an acceptor site has been shown for this protein in the transcription of chromatin in presence of nucleoplasmic receptor and indole acetic acid complex. A maximum stimulation in the synthesis of 9 – 12S RNA has been recorded.

Hormonal modifications of plant citrate synthase [formula omitted

Citrate synthase (EC 4.1.3.7.) from roots of bean seedlings and mitochondria of cauliflower buds was purified 400-fold and had specific activity of 6 to 10. Such enzyme was stimulated by the plant hormone indoleacetic acid (IAA). Consistent with the accepted molecular size of the enzyme, it was eluted as a single peak off Sephadex G-200. Treatment with IAA increased the molecular size of the enzyme. It is demonstrated that while increasing its activity and modifying its size, the hormone binds with the enzyme.

The effect of plant hormone indoleacetic acid (IAA) on hematological and biochemical parameters in mice

The subacute toxicity of plant hormone indoleacetic acid (IAA) was studied on Swiss albino mice. The studies include the gross general observation such as changes in body weight, hematological profiles [total count of red blood cells (RBC) and white blood cells (WBC), differential count of WBC, platelet count, hemoglobin (Hb)%], biochemical parameters of blood [serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT), serum alkaline phospatase(SALP), creatinine] and histopathology of the liver, kidney, lung, spleen, heart and brain of both control and experimental day-1 for consecutive 14 days, showed no significant change of hematological and biochemical parameters. No abnormalities were also found in the histopathology of the liver, kidney, lung, spleen, heart and brain in the experimental group of animals following same dose when compared with control group. This preliminary toxicological study suggests that the plant hormone indoleacetic acid (IAA) may be used safely for agricultural purposes and as an external preservative DOI: 10.3329/bjpp.v22i1.3561 Bangladesh J Physiol Pharmacol 2006; 22(1/2) : 5-8

Formation of a Complex Between a Derivative of the Plant Hormone Indoleacetic Acid and Ribonucleic Acid from Pea Seedlings.

Formation of a Complex Between a Derivative of the Plant Hormone Indoleacetic Acid and Ribonucleic Acid from Pea Seedlings.

Photo-inactivation of the Plant Hormone Indoleacetic Acid by Fluorescent Substances

THE fact that riboflavin and eosin, which are known to determine the photo-inactivation of indoleacetic acid2,3, are both fluorescent, led us to investigate whether other fluorescent substances would also be effective in sensitizing such a reaction. Quinine sulphate, aesculin and 2,3,5-triphenyl tetrazolium chloride were tested. It was found by both chemical and biological experiments that these compounds were all active. These substances are colourless, but fluoresce with a visible colour, absorbing light in the ultra-violet region. They are not related chemically, fluorescence being apparently the only property common to them. The present experiments do not necessarily show that there is a direct cause-and-effect relationship between fluorescence and the capacity of inducing the photo-inactivation of indoleacetic acid.