Addition Of Indole-3-acetic Acid Research Articles

Dynamic Investigation of Auxin on Germination of Sesamum Indicum Seed by 1H Spectroscopy and Chemical Shift Selection Imaging

Ger mination of sesame seeds in acidic and indole-3-acetic acid (IAA) liquid mediums was investigated using single pulse 1H spectroscopy and chemical shift selection imaging. The spectra and images demonstrated high correlation and reliability. Chemical shift selection imaging allowed for an intuitive comprehension of the dynamic distribution of metabolites and structural changes during germination, leading to a clearer understanding of IAA’s regulation on sesame metabolites, when combined with 1H spectra. Results showed that exogenous hormones accelerated the decomposition of lipid macromolecules before rapid radicle growth, while IAA delayed sesame development at this stage. However, post-growth delay, the addition of IAA effectively accelerated germination. This study confirms that 1H spectroscopy and chemical shift selection imaging can interpret the metabolic response of plants to the change in their internal physiological state and help to determine the optimal time to add IAA.

Nitric oxide acts upstream of indole-3-acetic acid in ameliorating arsenate stress in tomato seedlings

After their discovery, nitric oxide (NO) and indole-3-acetic acid (IAA) have been reported as game-changing cellular messengers for reducing abiotic stresses in plants. But, information regarding their shared signaling in regulating metal stress is still unclear. Herein, we have investigated about the joint role of NO and IAA in mitigation of arsenate [As(V)] toxicity in tomato seedlings. Arsenate being a toxic metalloid increases the NPQ level and cell death while decreasing the biomass accumulation, photosynthetic pigments, chlorophyll a fluorescence, endogenous NO content in tomato seedlings. However, application of IAA or SNP to the As(V) stressed seedlings improved growth together with less accumulation of arsenic and thus, preventing cell death. Interestingly, addition of c-PTIO, {2-(4-carboxyphenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide, a scavenger of NO} and 2, 3, 5-triidobenzoic acid (TIBA, an inhibitor of polar auxin transport) further increased cell death and inhibited activity of GST, leading to As(V) toxicity. However, addition of IAA to SNP and TIBA treated seedlings reversed the effect of TIBA resulting into decreased As(V) toxicity. These findings demonstrate that IAA plays a crucial and advantageous function in NO-mediated reduction of As(V) toxicity in seedlings of tomato. Overall, this study concluded that IAA might be acting as a downstream signal for NO-mediated reduction of As(V) toxicity in tomato seedlings.

Indole-3-acetic acid improves periphyton's resistance to ultraviolet-B: From physiological-biochemical properties and bacteria community to livestock-polluted water purification

Livestock-polluted water is a pressing water environmental issue in plateau pastoral regions, necessitating the adoption of eco-friendly solutions. Despite periphyton being a promising alternative, its efficacy is limited by the prevalence of intense ultraviolet radiation, particularly ultraviolet-B (UVB), in these regions. Therefore, this study employs molecular tools and small-scale trials to explore the crucial role of indole-3-acetic acid (IAA) in modulating periphyton characteristics and mediating nutrient removal from livestock-polluted water under UVB exposure. The results revealed that IAA augments periphyton's resilience to UVB stress through several pathways, including increasing periphyton's biomass, producing more extracellular polymeric substances (EPS), and enhancing antioxidant enzyme activities and photosynthetic activity of periphyton. Moreover, IAA addition increased periphyton's bacterial diversity, reshaped bacterial community structure, enhanced community stability, and elevated the R2 value of neutral processes in bacterial assembly from 0.257 to 0.651 under UVB. Practically, an IAA concentration of 50 mg/L was recommended. Small-scale trials confirmed the effectiveness of IAA in assisting UVB-stressed periphyton to remove nitrogen and phosphorus from livestock-polluted water, without the risk of nitrogen accumulation. These findings offer valuable insights into the protection of aquatic ecosystems in plateau pastoral regions based on periphyton property in an eco-friendly manner.

Auxin alone provokes retention of ASH1 mRNA in Saccharomyces cerevisiae mother cells.

The auxin-inducible degradation (AID) system can elicit conditional and reversible protein degradation as a tool to assess the role of essential proteins. Indeed, AID enables functional studies without the possibility of adaptation, which can occur with permanent gene deletions. The AID system relies on the addition of auxin molecules, such as indole-3-acetic acid (IAA), as a means to launch the degradation of the protein of interest. In this context, it is extremely important to control for the effect of auxin addition alone. To study the role of essential proteins in the process of selective mRNA delivery to daughter cells in Saccharomyces cerevisiae , we first controlled for the effect of adding IAA to cells that cannot perform AID-mediated degradation. We found that auxin alone restricted ASH1 delivery to daughter cells, as ASH1 mRNA started being retained in the mother cell as soon as thirty minutes after IAA addition. Thus, our data warn about the danger of not systematically including auxin-treated cells incapable of degradation in every AID-related experiment. Furthermore, given previous data reporting the ability of auxin to inhibit the master growth regulator TORC1 in S. cerevisiae , our data suggest that TORC1 could control the selective delivery of mRNAs to daughter cells.

Ameliorative effects of endogenous and exogenous indole-3-acetic acid on atrazine stressed paddy field cyanobacterial biofertilizer Cylindrospermum stagnale

Across the world, paddy fields naturally harbour cyanobacteria that function as biofertilizers and secrete various compounds like Indole-3-acetic acid (IAA) that help organisms in regulating their growth. Also, paddy field farming utilizes large amounts of pesticides (e.g. atrazine); but their continued application in the agricultural field causes toxicity in non-target cyanobacterial species that hinder their performance as a biofertilizer. Hence, the current study is an attempt to ameliorate the atrazine stress in cyanobacterium Cylindrospermum stagnale by addition of IAA (1 mM each) under different atrazine levels (0, 60, 80, 100, 120, 140 µg/l). Atrazine toxicity affected C. stagnale in a dose-dependent manner further experiments revealed that both the exogenous and endogenous IAA mitigated the detrimental effects of atrazine. It reduced MDA content and simultaneously increased chlorophyll content, total protein content, and multiple antioxidant enzyme activities [superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX)] at 140 µg/l. A molecular docking study revealed that the pesticide binds to the D1 protein of the photoelectric chain in photosynthesis. Hence, the application of IAA or cyanobacterial biofertilizer that secretes a sufficient amount of IAA may assist sustainable agriculture in counteracting the atrazine toxicity.

Application of indole-3-acetic acid in microalgae cultivation to improve the feasibility of simultaneously purifying wastewater, fixing CO2 and producing fatty acids under Hg stress

Alleviating the toxicity of mercury (Hg), improving the yield of Chlorella vulgaris ( C. vulgaris ) biomass and fatty acids, purifying wastewater, and promoting carbon dioxide (CO 2 ) fixation are important goals of research in the cultivation of microalgae in wastewater-injected flue gas . Accordingly, indole-3-acetic acid (IAA) was selected as an additive to help achieve these goals. The results showed that IAA could reduce cell damage and malondialdehyde (MDA) content, which may be attributed to the improved activities of detoxification components in reactive oxygen species (superoxide dismutase (SOD), catalase (CAT), etc.) and the improved expression of important photosynthesis genes ( psbA , rbcL , etc.), ultimately leading to enhanced chlorophyll synthesis rates and biomass under 0–30 μg m −3 Hg concentrations. Moreover, wastewater was found to have a high bioremediation efficiency because C. vulgaris grew well in all treatments, and the rates of nitrogen and phosphorus removal were higher than 97.64%. Additionally, the CO 2 fixation rate (170.98–220.92 mg CO 2 ·L −1 ·d −1 ) of C. vulgaris was enhanced with the addition of IAA under Hg stress. More importantly, it was found that 2 mg L −1 IAA is beneficial for improving lipid accumulation (34040.42 and 72564.81 μg g −1 ) under 10–30 μg m −3 Hg concentrations, and the lipid content increased by 384.90% and 65.19% at 10 and 30 μg m −3 Hg respectively. A modified Droop kinetic function that was related to both the phosphorus quota and nitrogen quota was implemented and described C. vulgaris growth well ( R 2 ≥0.994). • Flue gas with Hg has the potential to cultivate microalgae for biodiesel production. • IAA attenuated the inhibitory effect of Hg on C. vulgaris. • IAA enhanced the CO 2 -fixation ability of C. vulgaris under Hg stress. • IAA induced fatty acid biosynthesis, especially for MUFAs, in C. vulgaris cells.

Endogenous indole-3-acetic acid and nitric oxide are required for calcium-mediated alleviation of copper oxide nanoparticles toxicity in wheat seedlings.

The action of nanoparticles is increasingly being studied in recent years to minimize their toxic impacts. Besides this, efforts are also being made to minimize their toxicity in crop plants by using various chemicals, i.e. nutrients, donors of signaling molecules, plant hormones, and so on. However, associated alleviatory mechanisms are still not well known. Therefore, in the present study, we have investigated the toxicity of CuONPs and its mitigation by exogenously applied calcium (Ca). The focus was on whether indole-3-acetic acid (IAA) or endogenous nitric oxide (NO) has any role in accomplishing this task. CuONPs declined wheat growth due to increased accumulation of Cu and oxidative stress markers such as superoxide radicals, hydrogen peroxide, and lipid peroxidation (malondialdehyde) and it was also accompanied by a decline in endogenous NO. CuONPs also altered the redox status of ascorbate and glutathione by inhibiting the activity of their regenerating enzymes. This collectively leads to cell death in wheat seedlings. However, exogenous supplementation of Ca mitigated toxic effects of CuONPs by reducing the excess accumulation of Cu, which caused remarkable enhancement in growth, protein contents, photosynthetic pigments, and endogenous NO; altogether protecting wheat roots from cell death. Interestingly, addition of 2,3,5-triiodobenzoic acid (TIBA) further increased CuONPs toxicity even in the presence of Ca, but the addition of IAA rescued this effect of TIBA. These results clearly show that Ca mitigates CuONPs toxicity in wheat seedlings by involving IAA. Further, the results also showed that endogenous NO has a positive and indispensable role in Ca-mediated mitigation of CuONPs toxicity in wheat seedlings.

YUCCA-Mediated Biosynthesis of the Auxin IAA Is Required during the Somatic Embryogenic Induction Process in Coffea canephora.

Despite the existence of considerable research on somatic embryogenesis (SE), the molecular mechanism that regulates the biosynthesis of auxins during the SE induction process remains unknown. Indole-3-acetic acid (IAA) is an auxin that is synthesized in plants through five pathways. The biosynthetic pathway most frequently used in this synthesis is the conversion of tryptophan to indol-3-pyruvic acid (IPA) by tryptophan aminotransferase of Arabidopsis (TAA) followed by the conversion of IPA to IAA by enzymes encoded by YUCCA (YUC) genes of the flavin monooxygenase family; however, it is unclear whether YUC-mediated IAA biosynthesis is involved in SE induction. In this study, we report that the increase of IAA observed during SE pre-treatment (plants in MS medium supplemented with 1-naphthaleneacetic acid (NAA) 0.54 µM and kinetin (Kin) 2.32 µM for 14 days) was due to its de novo biosynthesis. By qRT-PCR, we demonstrated that YUC gene expression was consistent with the free IAA signal found in the explants during the induction of SE. In addition, the use of yucasin to inhibit the activity of YUC enzymes reduced the signal of free IAA in the leaf explants and dramatically decreased the induction of SE. The exogenous addition of IAA restored the SE process in explants treated with yucasin. Our findings suggest that the biosynthesis and localization of IAA play an essential role during the induction process of SE in Coffea canephora.

Modification of plant regeneration medium decreases the time for recovery of Solanum lycopersicum cultivar M82 stable transgenic lines

Tomato (Solanum lycopersicum) has rapidly become a valuable model species for a variety of studies including functional genomics. A high-throughput method to obtain transgenic lines sooner than standard methods would greatly advance gene function studies. The goal of this study was to optimize our current transformation method by investigating medium components that would result in a decreased time for recovery of transgenics. For this study, 6-day-old cotyledon explants from Solanum lycopersicum cultivar M82 in vitro-grown seedlings were infected with the Agrobacterium tumefaciens strain LBA4404 containing the binary vector pBI121. This vector contains the β-glucuronidase reporter gene and the neomycin phosphotransferase II selectable marker gene that confers resistance to kanamycin. Modification of our standard plant regeneration medium with indole-3-acetic acid (IAA) at concentrations of either 0.05 or 0.1 mg/l decreased the recovery time for transgenic lines by 6 weeks as compared to our standard medium that contains zeatin as the only plant growth regulator. We observed 50 and 54 % transformation efficiency on plant regeneration medium containing 0.05 and 0.1 mg/l IAA, respectively. Moreover, addition of 1 mg/l IAA to the root induction medium resulted in earlier root development than medium that did not contain IAA. Addition of IAA to the plant regeneration and rooting media did not have any negative effects on plant development. Recovery of transgenic lines in a shorter time results in higher throughput for the introduction of gene constructs and has the potential to decrease the time and resources needed to complete investigations of gene function.

Effects of indole-3-acetic acid on arsenic uptake and antioxidative enzymes in Pteris cretica var. nervosa and Pteris ensiformis

ABSTRACTA hydroponic experiment was conducted to investigate the effects of indole-3-acetic acid (IAA) on arsenic (As) uptake and antioxidative enzymes in fronds of Pteris cretica var. nervosa (As hyperaccumulator) and Pteris ensiformis (non-hyperaccumulator). Plants were exposed to 2 mg L−1 As(III), As(V) or dimethylarsinic acid (DMA) and IAA concentrations for 14 d. The biomass and total As in the plants significantly increased at 30 mg L−1 IAA. Superoxide dismutase (SOD) activities significantly increased with IAA addition. Catalase (CAT) activities showed a significant increase in P. ensiformis exposed to three As species at 30 or 50 mg L−1 IAA but varied in P. cretica var. nervosa. Peroxidase (POD) activities were unchanged in P. ensiformis except for a significant decrease at 50 mg L−1 IAA under As(III) treatment. However, a significant increase was observed in P. cretica var. nervosa at 10 mg L−1 IAA under As(III) or DMA treatment and at 50 mg L−1 IAA under As(V) treatment. Under DMA stress, malondialdehyde contents in fronds of P. cretica var. nervosa showed a significant decrease at 10 mg L−1 IAA but remained unchanged in P. ensiformis. Therefore, IAA enhanced As uptake and frond POD activity in P. cretica var. nervosa under As stress.

Biosynthesis and Secretion of Indole-3-Acetic Acid and Its Morphological Effects on Tricholoma vaccinum-Spruce Ectomycorrhiza.

Fungus-derived indole-3-acetic acid (IAA), which is involved in development of ectomycorrhiza, affects both partners, i.e., the tree and the fungus. The biosynthesis pathway, excretion from fungal hyphae, the induction of branching in fungal cultures, and enhanced Hartig net formation in mycorrhiza were shown. Gene expression studies, incorporation of labeled compounds into IAA, heterologous expression of a transporter, and bioinformatics were applied to study the effect of IAA on fungal morphogenesis and on ectomycorrhiza. Tricholoma vaccinum produces IAA from tryptophan via indole-3-pyruvate, with the last step of this biosynthetic pathway being catalyzed by an aldehyde dehydrogenase. The gene ald1 was found to be highly expressed in ectomycorrhiza and induced by indole-3-acetaldehyde. The export of IAA from fungal cells is supported by the multidrug and toxic extrusion (MATE) transporter Mte1 found in T. vaccinum. The addition of IAA and its precursors induced elongated cells and hyphal ramification of mycorrhizal fungi; in contrast, in saprobic fungi such as Schizophyllum commune, IAA did not induce morphogenetic changes. Mycorrhiza responded by increasing its Hartig net formation. The IAA of fungal origin acts as a diffusible signal, influencing root colonization and increasing Hartig net formation in ectomycorrhiza.

The effects of explant source and hormone content on plant regeneration and induction of tetraploids in Humulus lupulus L.

Shoot regeneration was induced after long-term culture of stem- and petiole-derived callus of Humulus lupulus cv. ‘Iunga’. The effects of explant type and plant growth regulators on the regeneration efficiency and polyploid induction were estimated. Callus initiated from stem fragments showed significantly higher shoot regeneration than that obtained from petioles. Both types of explants were able to regenerate shoots if cultured in the presence of auxin and cytokinin. The mean number of shoots per explant ranged from 6.2 to 21.8 for stem-derived callus and from 1.0 to 14.6 for petiole-derived callus. The highest number of shoots from stem-derived callus was obtained on Murashige and Skoog (MS) medium containing 14.23 μM zeatin riboside and 0.57 μM indole-3-acetic acid (IAA), while MS medium supplemented with 8.87 μM 6-benzylaminopurine (BA) and 0.57 μM IAA produced the highest shoot regeneration in petioles. Flow cytometry revealed that long-term callus cultures, over 23 wk old, led to DNA amplification and formation of tetraploids among the regenerated plants. However, there was a distinct inter-explant diversity in the frequency at which polyploid lines regenerated. The highest number of tetraploids, 9.4%, was obtained from petiole-derived callus, and the number of polyploids was clearly enhanced by the addition of IAA to the regeneration medium.

Growth responses to temperature, salinity and nutrient variations, and biomass variation and phenology of Ahnfeltia plicata (Rhodophyta, Ahnfeltiales): a commercially interesting agarophyte from the Magellanic Region, Chile

Ahnfeltia plicata (Hudson) E.M. Fries (Rhodophyta, Ahnfeltiales) is one of the most commercially important agarophytes in the world for its production of agar that is high quality and low in sulfate content. In the Magellanic Region, A. plicata forms extensive beds with high biomass production, which could be commercially exploited for agar production. The purposes of this study were to determine the optimal conditions of temperature, salinity, and culture medium; to evaluate the effects of different types and concentrations of auxins and cytokinins on growth of red and yellow gameto- phytes; and to provide background information on ecological parameters of natural population of A. plicata .T emperatures of 5, 8, 15, and 23 °C were tested, and the interaction of salinity of 25 and 35 psu with Provasoli enriched medium in half (PES/2) and quarter strength (PES/4), and with von Stosch enriched medium in half (VSES/2) and quarter strength (VSES/4) was also conducted. Concentrations of 5.0 and 50.0 μ Mo f two auxins (indole-3-acetic acid (IAA), 2,4-dichlorophenoxyacetic acid (2,4-D)), and two cytokinins (isopentenyladenine (iP) and benzylaminopurine) were added to VSES medium and gelled with 0.5 % agar. Each treatment was tested with three replicates. Red gametophytes of A. plicata tolerate a range of temperature variation, from 5 to 23 °C, and the optimum temperature for growth was 15 °C. The highest growth rate was observed in salinity of 35 psu with half strength of von Stosch culture medium. Red and yellow gametophytes showed different re- sponses to plant growth regulators, and red gametophytes were more sensitive than yellow ones to the addition of IAA and high concentration of iP. However, growth of red gametophytes of A. plicata was stimulated by 2,4-D. The differential sensitivity of red and yellow gametophytes to plant growth regulators sug- gests the need to test other types and concentrations of auxins and cytokinins.

Investigation of the interactions between indole-3-acetic acid and catalase: A spectroscopic study in combination with second-order calibration and molecular docking methods

The interactions between indole-3-acetic acid (IAA) and the important antioxidant enzyme catalase (CAT) have been studied by Ultraviolet-visible (UV-vis) and fluorescence spectroscopic methods. The decrease of the absorption intensity of CAT at 270 nm and 407 nm in UV-vis spectra with the addition of IAA indicated the interactions between CAT and IAA. The three-way excitation–emission matrix spectra combined with parallel factor analysis (PARAFAC) was used to provide the individual concentration information of IAA, CAT, and IAA–CAT in the reaction system. The PARAFAC analysis showed that a 1:1 IAA–CAT complex formed at the equilibrium point. Constant wavelength synchronous fluorescence spectrometry (SFS) showed that the binding of IAA resulted in the micro-environment changes around tryptophan (Trp) and tyrosine (Tyr) residues. Molecular docking studies provide a good structural basis to explain the experimental results. This work is valuable for providing a deeper insight into the interaction mechanism of IAA with CAT.

Exogenous indole-3-acetic acid could reduce the accumulation of aluminum in root apex of wheat (Triticum aestivum L.) under Al stress

Indole-3-acetic acid (IAA) is hormones in higher plants and participates in plant growth regulation and stress resistance including Al stress. The reduction of root apex aluminum (Al) content by exogenous IAA treatment was hypothesized to be effective in alleviating the adverse effect of high Al concentration in wheat root growth. To investigate the role of IAA in lowering root apex Al content, Al-tolerant wheat (ET8) was studied in Al solution (50 µM), co-treated with IAA (25 µM) and anion channel inhibitors (5 µM NIF or A9C) or IAA transport inhibitors (5 µM TIBA or NPA) under acidic condition for 24 h. Treatments were as fellows: control (0.5 µM CaCl 2 ), Al (50 µM), Al (50 µM) + IAA (25 µM), Al (50 µM) + IAA (25 µM) + NIF (or A9C, 5 mM), Al (50 µM) + NPA (or TIBA, 5 µM). Al content in root apex, rhizosphere pH and PM H + -ATPase activity were studied. The results showed that co-treatment with IAA reduced root apex Al content by 42% compared to Al treatment. Anion channel inhibitors enhanced the accumulation of Al in root apex by 27% (or 32%) (NIF or A9C), while addition of IAA neutralized its promoting effect. The co-treatment with IAA increased rhizosphere pH by alleviating the decrease of plasma membrane H + -ATPase activity, while IAA transport inhibitors (NPA or TIBA) suppressed the elevation of rhizosphere pH. The current results suggested that IAA could be effective in alleviating Al toxicity through reducing Al accumulation in wheat root apex.

Transcriptome Analysis of the Rhizosphere Bacterium Azospirillum brasilense Reveals an Extensive Auxin Response

The rhizosphere bacterium Azospirillum brasilense produces the auxin indole-3-acetic acid (IAA) through the indole-3-pyruvate pathway. As we previously demonstrated that transcription of the indole-3-pyruvate decarboxylase (ipdC) gene is positively regulated by IAA, produced by A. brasilense itself or added exogenously, we performed a microarray analysis to study the overall effects of IAA on the transcriptome of A. brasilense. The transcriptomes of A. brasilense wild-type and the ipdC knockout mutant, both cultured in the absence and presence of exogenously added IAA, were compared.Interfering with the IAA biosynthesis/homeostasis in A. brasilense through inactivation of the ipdC gene or IAA addition results in much broader transcriptional changes than anticipated. Based on the multitude of changes observed by comparing the different transcriptomes, we can conclude that IAA is a signaling molecule in A. brasilense. It appears that the bacterium, when exposed to IAA, adapts itself to the plant rhizosphere, by changing its arsenal of transport proteins and cell surface proteins. A striking example of adaptation to IAA exposure, as happens in the rhizosphere, is the upregulation of a type VI secretion system (T6SS) in the presence of IAA. The T6SS is described as specifically involved in bacterium-eukaryotic host interactions. Additionally, many transcription factors show an altered regulation as well, indicating that the regulatory machinery of the bacterium is changing.

Changes in endogenous cytokinin profiles in micropropagated Harpagophytum procumbens in relation to shoot-tip necrosis and cytokinin treatments

Changes in cytokinin (CK) profiles and their physiological implications in micropropagated Harpagophytum procumbens [(Burch.) DC. ex Meisn.] tissues in relation to shoot-tip necrosis (STN) and CK treatments were studied. Total CK content was quantified in benzyladenine (BA)-treated necrotic and normal plantlets and in plantlets treated with the CKs BA, meta-topolin (mT) and meta-topolin riboside (mTR) with and without the auxin indole-3-acetic acid (IAA). Generally necrotic shoots yielded more total CK compared to normal shoots. Cytokinin accumulation was higher at the basal section (basal > middle > top). Further analysis of the CKs based on structural and functional forms revealed excessive accumulation of 9-glucosides (deactivation products—toxic metabolites) and limited amounts of O-glucosides (storage forms—re-utilizable) in necrotic and BA-treated shoots compared to normal and topolin-treated cultures. The addition of IAA enhanced the formation of 9-glucosides in BA-treated cultures but reduced it in topolin-treated cultures. The symptom of STN could therefore be attributed to conversion of active cytokinins to other forms such as 9-glucosides which are neither active nor reversibly sequestrated to active forms. Literature shows that metabolites like 9-glucosides of BA have a detrimental effect in plant tissue culture.

Glutathione synthesis is essential for pollen germination in vitro

BackgroundThe antioxidant glutathione fulfills many important roles during plant development, growth and defense in the sporophyte, however the role of this important molecule in the gametophyte generation is largely unclear. Bioinformatic data indicate that critical control enzymes are negligibly transcribed in pollen and sperm cells. Therefore, we decided to investigate the role of glutathione synthesis for pollen germination in vitro in Arabidopsis thaliana accession Col-0 and in the glutathione deficient mutant pad2-1 and link it with glutathione status on the subcellular level.ResultsThe depletion of glutathione by buthionine sulfoximine (BSO), an inhibitor of glutathione synthesis, reduced pollen germination rates to 2-5% compared to 71% germination in wildtype controls. The application of reduced glutathione (GSH), together with BSO, restored pollen germination and glutathione contents to control values, demonstrating that inhibition of glutathione synthesis is responsible for the decrease of pollen germination in vitro. The addition of indole-3-acetic acid (IAA) to media containing BSO restored pollen germination to control values, which demonstrated that glutathione depletion in pollen grains triggered disturbances in auxin metabolism which led to inhibition of pollen germination.ConclusionsThis study demonstrates that glutathione synthesis is essential for pollen germination in vitro and that glutathione depletion and auxin metabolism are linked in pollen germination and early elongation of the pollen tube, as IAA addition rescues glutathione deficient pollen.

Poinsettia ‘Prestige™ Red’ (Euphorbia pulcherrima) In Vitro Propagation

Slow growth rate of plantlets, few micro-shoots per explant, and slow root growth rate are restrictions of in vitro propagation of poinsettia (Euphorbia pulcherrima Willd. ex Koltz). The purpose of this research was to develop an efficient in vitro proliferation technique for poinsettia ‘Prestige™ Red’. Explants (apical buds and axillary buds) placed on Murashige and Skoog (MS) basal medium containing only 6-benzylaminopurine (BA) and combinations of BA and indole-3-acetic acid (IAA) mostly produced red callus, which is productive and some white and gray–green calluses at the base of plantlets after 1 month, whereas explants in a medium without plant growth regulators (PGRs) produced no callus. Addition of IAA into the rooting medium increased rooting efficiency; plantlets grown in half-strength MS salts and vitamins with 28.5 μM IAA initiated rooting 11 days earlier than the plantlets grown with no PGRs. Optimization of PGR concentrations during poinsettia micropropagation helped resolve previous restrictions of in vitro poinsettia proliferation. Chemical names used: 6-benzylaminopurine (BA); indole-3-acetic acid (IAA)

Variations of Water Uptake, Lipid Consumption, and Dynamics during the Germination of Sesamum indicum Seed: A Nuclear Magnetic Resonance Spectroscopic Investigation

Germination in sesame seeds (Sesamum indicum L.) in water and in indole-3-acetic acid (IAA) solution is investigated with magic-angle-spinning (MAS) solid state nuclear magnetic resonance (NMR) spectroscopy, supplemented by liquid state NMR spectroscopy. The spectra show good resolution and can be assigned with sufficient confidence. The characteristic spectral peaks and relaxation rates were monitored during the entire course of germination for better understanding of the biophysical and biochemical mechanisms involved in the triphasic water uptake of the seed. A highly positive correlation is found between water uptake and lipid consumption during germination. No significant variation is observed in the relaxation times for the lipid protons during the first two stages of triphasic water uptake, while evident differences are observed for water proton relaxation rates in all stages. Although the total amount of water uptake is largely not changed as a result of IAA, the addition of IAA in seed-germination medium has shown some prominent effects on the germination process, e.g, it suppresses lipid consumption and water mobility, and it reduces the longitudinal and transverse relaxation times of lipid protons and causes a more scattered range for these parameters.