Indolylbutyric Acid Research Articles

Regulation of in vitro morphogenesis in maize inbreds of the Lancaster group

The aim of this work is the comparative evaluation of the influence of physiologically active substances (PAS) on the ratio of morphogenesis types in vitro and plant regeneration in callus tissues of maize inbreds of the Lancaster heterotic group. Lancaster inbreds of Ukrainian selection DК267, DК6080 and DК298 and lines PLS61, A188 and Chi31 of foreign selection which represented eponymous heterotic groups were selected for into the research. For callusogenesis induction immature embryos of 1.0–1.5 mm in length were planted on a modified N6 medium with 30 g/l sucrose. For regeneration the 30-day callus tissue was transplanted to a modified MS medium containing 20 g/l sucrose and various PAS: 6-benzylaminopurine (BAP) (0.1 mg/l) or indolylbutyric acid (IBA) (1.0 mg/l), or cefotaxime (CT) (150 mg/l). Morphogenesis and plant regeneration were obtained in callus tissue by organogenesis through the formation of leaf-like structures or shoots only without roots (hemmogenesis) and by embryogenesis through the development of embryos with the cooperative laying of the apexes of the shoot and the root. The predominant type of in vitro morphogenesis in both groups of genotypes was organogenesis. A tendency to increasing the embryogenesis level among Lancaster inbreds in comparison with the other investigated groups was observed. A certain tendency to increase the level of embryogenesis on a medium for regeneration with IBA, compared to other PAS, was marked. So, for the Lancaster group the embryogenesis level on the medium with IBA was 33.3%, while for the other investigated genotypes it was about 10.3%. Regeneration frequency was 45.8 plantlets/100 calli for Lancaster inbred DК298, 42.2 plantlets/100 calli for DК267 and 5.6 plantlets/100 calli for DК6080. Regeneration frequency of inbred PLS61 was 204.0 plantlets/100 calli, 100.0 plantlets/100 calli for Chi31 and 11.1 plantlets/100 calli for А188. Observed reductions in capacityfor plant regeneration of Lancaster inbreds may have been due to their pedigree. These inbreds belong to the commercial heterotic group that was not specially selected for increased regenerative ability, unlike the model inbreds of other heterotic groups. Overall, the level of regeneration frequency in the Lancaster group was 44.8 plantlets/100 calli on the medium under BAP, 41.4 plantlets/100 calli under IBA, and 20.7 plantlets/100 calli with CT. In general, the level of regeneration frequency for non-Lancaster heterotic groups reached 89.7 plantlets/100 calli on the medium with BAP, 96.7 plantlets/100 calli under IBA, and 93.1 plantlets/100 calli under CT. To enhance embryogenesis and frequency of regeneration for maize inbreds of the Lancaster group 30 g/l sucrose in the callusogenesis medium and physiologically active substance indolylbutyric acid (1.0 mg/l) in the medium for regeneration can be recommended.

Reasoned opinion on the review of the existing maximum residue levels (MRLs) for indolylbutyric acid according to Article 12 of Regulation (EC) No 396/2005

Reasoned opinion on the review of the existing maximum residue levels (MRLs) for indolylbutyric acid according to Article 12 of Regulation (EC) No 396/2005

ВЕГЕТАТИВНОЕ РАЗМНОЖЕНИЕ Actinidia deliciosa В УСЛОВИЯХ СУБТРОПИКОВ РОССИИ ПРИ ПРИМЕНЕНИИ СТИМУЛЯТОРОВ РОСТА

The problem in propagation of planting material is always on the forefront, if a new crop is implemented in practice of industrial horticulture. It is known that Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson (kiwifruit) refers to the crops, which are propagated with certain difficulties. Nevertheless, the demand of kiwi on the world market is not fully satisfied, the trend towards expanding area under this crop are saved. Here we show the results of the 17-years studies of the impact of growth stimulants (i.e. indolyl acetic acid and indolyl butyric acid, zircon, potassium humate and Rhizopon) on propagation by green and woody cuttings in Actinidia deliciosa. The experiments were carried out with Hayward, Hayward K-10, Bruno, Monty, Kivaldi, Ellison, Matua, and Tomuri cultivars of kiwifruit. Action of different concentrations of indolyl butyric acid (50, 70, 100 mg/l) and indolyl acetic acid (50, 100, 200 mg/l), zircon (1.0 mg/l), potassium humate (1.0 mg/l), Rhizopon (growth powder) was considered. Awakening of the buds occurred 12-15 days after planting. On 25-30th day the adventitious root formation started, and after 120 days the rooted cuttings were ready to transfer into containers. An average varietal rooting of green cuttings in control was 20 %, and the growth stimulants increased it 1.9-3.2 times. An average varietal rooting of woody cuttings in control made up 26 %, and the growth stimulants increased it 1.5-2.5 times. Shoots rooted cuttings have reached the height of 15.2-35.0 cm, had 10-16 leaves and the diameter of the trunk of 1.6-1.8 mm The best results in both cases were shown by indole-butyric acid (in concentration of 100 mg/l) and Rhizopon. The best rooting ability was observed in Monty, Bruno and Hayward cultivars propagated by both green and woody cuttings. Currently in Sochi region no pesticides are required in kiwi plantations due to no diseases and pests observed. Thus, kiwi cultivation in the resort area of Russian humid subtropics is considered appropriative and effective.

IBA e carboidratos no enraizamento de brotações procedentes de estacas radiciais de Rubus Spp.

Este trabalho objetivou verificar o efeito do ácido indol-3-butírico (IBA) e o teor de carboidratos na promoção do enraizamento em estacas de brotações de amoreira-preta. O experimento foi conduzido de junho a agosto de 2010, na UNESP de Botucatu - SP, sendo o delineamento em blocos casualizados, com seis concentrações de IBA e seis repetições, com a parcela constituída por 12 brotações. Os tratamentos constaram de seis concentrações de IBA, na forma de solução: T1= 0 mg L-1; T2= 250 mg L-1; T3= 500 mg L-1; T4= 1.000 mg L-1; T5= 2.000 mg L-1, e T6= 4.000 mg L-1 aplicados na base das brotações, durante dez segundos. Após 60 dias, foram avaliados: a porcentagem de enraizamento e o teor de carboidratos solúveis. As maiores concentrações de IBA inibiram o enraizamento das estacas de brotações. O aumento nos teores de açúcares da parte aérea com relação às raízes pode indicar que a parte aérea atuou como fonte de fotoassimilados e, dentre eles, açúcares solúveis, para promover o enraizamento das brotações.

Indolyl-3-butyric acid-induced Arabidopsis stomatal opening mediated by 3′,5′-cyclic guanosine-monophosphate

It has been pharmacologically suggested that 3',5'-cyclic guanosine-monophosphate (cGMP) mediates indolyl-3-butyric acid (IBA)-induced stomatal opening. In Arabidopsis thaliana (L.) Heynh., such investigations compared the wild type (Columbia and Ws ecotypes) to mutants knockout for either GTP-binding protein (G protein) α subunit 1 (gpa1-4), putative G protein-coupled receptor 1 (gcr1-5), calcineurin B-like isoform 1 (cbl1) or 9 (cbl9), or the NADPH oxidases AtrbohD and AtrbohF (atrbohD/F). Stomatal opening to IBA or the permeant cGMP analogue, 8-bromo-cGMP (8-Br-cGMP) was abolished in the atrbohD/F mutant. The IBA response was fully or partially suppressed, respectively, in the gcr1-5 mutant, or the gpa1-4 and cbl1 mutants. In the cbl9 mutant, the response to IBA or 8-Br-cGMP, respectively, was partially or fully suppressed. Phenylarsine oxide (PAO) affected the IBA response, which the cbl1 mutant overlapped or the gpa1-4 and cbl9 mutants increased up to 100% inhibition. 6-anilino-5,8-quinolinedione, mas17, the (Rp)-diastereomer of 8-bromo-3',5'-cyclic guanosine monophosphorothioate (Rp-8-Br-cGMPS), nicotinamide, ruthenium red (RRed), 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), cyclosporine A (CsA) and FK506 converged to affect the IBA response, which the gpa1-4 and cbl9 mutants overlapped or the cbl1 mutant and PAO increased up to 100% inhibition. Rp-8-Br-cGMPS, nicotinamide, RRed, BAPTA, CsA or FK506 paralled the cbl9 and atrbohD/F mutants to abolish the 8-Br-cGMP response. Based on so far revealed features of these mutants and pharmacological compounds, these results confirmed cGMP as a Ca(2+)-mobilizing second messenger for apoplastic auxin whose perception and transduction would implicate a seven-transmembrane receptor - G protein - guanylyl cyclase unit at the guard cell plasma membrane.

Conclusion on the peer review of the pesticide risk assessment of the active substance indolylbutyric acid

Conclusion on the peer review of the pesticide risk assessment of the active substance indolylbutyric acid

Crescimento de plantas de Salvia officinalis sob ação de reguladores de crescimento vegetal

O objetivo deste trabalho foi estimar os parâmetros da análise de crescimento em função de diferentes reguladores vegetais aplicados na parte aérea de plantas de Salvia officinalis L. Para tanto,o experimento foi instalado em casa de vegetação do Departamento de Botânica, Instituto de Biociências, da Universidade Estadual Paulista, Botucatu, SP. Os tratamentos consistiram na pulverização da solução de 100mg L-1 de ácido giberélico (GA3); 100mg L-1 de benzilaminopurina (BAP); 100mg L-1 de ácido 2-cloroetil-fosfônico (ethephon); Stimulate® a 2% (90mg L-1 de cinetina, 50mg L-1 de ácido giberélico e 50mg L-1 de ácido indolilbutírico) e água (testemunha). As aplicações foram realizadas em três épocas, aos 15, 25 e 35 dias após o transplante (d.a.t.) e o crescimento foi avaliado em cinco épocas de coletas a intervalos de 21 dias, sendo a primeira realizada aos 47 (d.a.t.). Foram determinados os parâmetros fisiológicos da análise de crescimento: razão de área foliar (RAF), área foliar específica (AFE), taxa assimilatória líquida (TAL) e taxa de crescimento relativo (TCR). Os resultados mostram que os reguladores de crescimento vegetal influenciaram os parâmetros fisiológicos da análise de crescimento. As plantas tratadas com BAP apresentaram maiores valores de RAF aos 47 d.a.t., já as plantas tratadas com GA3, a TAL apresentou aumento até o 131 d.a.t. A TCR é decrescente para todos os tratamentos com reguladores de crescimento vegetal testados e a testemunha.

Efficient Agrobacterium-mediated transformation of Vigna mungo using immature cotyledonary-node explants and phosphinothricin as the selection agent

Herbicide (Basta®)-tolerant Vigna mungo L. Hepper plants were produced using cotyledonary-node and shoot-tip explants from seedlings germinated in vitro from immature seeds. In vitro selection was performed with phosphinothricin as the selection agent. Explants were inoculated with Agrobacterium tumefaciens strain LBA4404 (harboring the binary vector pME 524 carrying the nptII, bar, and uidA genes) in the presence of acetosyringone. Shoot regeneration occurred for 6 wk on regeneration medium (MS medium with 4.44 μM benzyl adenine, 0.91 μM thidiazuron, and 81.43 μM adenine sulfate) with 2.4 mg/l PPT, explants being transferred to fresh medium every 14 d. After a period on elongation medium (MS medium with 2.89 μM gibberellic acid and 2.4 mg/l PPT), β-glucuronidase-expressing putative transformants were rooted in MS medium with 7.36 μM indolyl butyric acid and 2.4 mg/l PPT. β-Glucuronidase expression was observed in the primary transformants (T0) and in the seedlings of the T1 generation. Screening 128 GUS-expressing, cotyledonary-node-derived, acclimatized plants by spraying the herbicide Basta® at 0.1 mg/l eliminated nonherbicide-resistant plants. Southern hybridization analysis confirmed the transgenic nature of the herbicide-resistant plants. All the transformed plants were fertile, and the transgene was inherited by Mendelian genetics. Immature cotyledonary-node explants produced a higher frequency of transformed plants (7.6%) than shoot-tip explants (2.6%).

Use of rooted leaves for screening of Brassica germplasm response to clubroot (Plasmodiophora brassicae) and downy mildew (Hyaloperonospora parasitica)

Rooted leaves and cotyledons of various cruciferous crops were used for the screening of Brassica germplasm response to two obligatory pathogens: clubroot (Plasmodiophora brassicae) and downy mildew (Hyalope-ronospora parasitica). The development of roots was induced after 20-hour dipping of leaf pedicels in the mixture of growth regulators: indolyl-butyric acid (10 mg/l) and nicotinic acid (5 mg/l). The detached rooted leaves and cotyledons were maintained in 250ml plastic containers with perlite under fluorescent tubes in a growth chamber. With additional foliar fertilizing they remain vital for four months, producing clubroot galls on roots when dip-inoculated with Plasmodiophora spores and sporulating mycelia of downy mildew on leaves after drop inoculation with Hyaloperonospora parasitica. The possibilities of enhancing the sensitivity of this alternative assay in combination with immunochemical methods are discussed.    

The effect of growth regulators on the rooting of shoots of the peach rootstock Ishtara in in vitro conditions

The effect of indolyl-3-butyric acid (IBA) and paclobutrazol (PP 333) on the rooting of shoots of the Ishtara peach rootstock was examined in in vitro conditions in light. In the first stage of the experiments the effect of the IBA concentration (0, 0.75, 1.5 mg/l) was studied and in the second stage the effect of the interaction of IBA (0.75 mg/l) and PP 333 (0.06 and <br />0.12 mg/l) in the MS medium, which is optimal for the rooting of the peach rootstock Ishtara. During shoot cultivation we evaluated root formation (average length and number). During rhizogenesis the production of ethylene, ethane and CO<sub>2</sub> by the shoots and the level of abscisic acid (ABA) in the shoot base was monitored in in vitro conditions. Shoots cultivated on the MS medium with <br />1.5 mg/l of IBA produced the highest number of roots and the longest roots that produced the lowest level of ethylene and CO<sub>2</sub> and the level of ABA was the lowest in the bases.  

Utilisation of in vitro Techniques in Rescue of Gene Resources of Meadow Vetchling (Lathyrus pratensis L.)

In the case of poor germination of seed samples and minimal number of seedlings obtained, in vitro methods can be used to revitalise and recover the gene resource. The highest germination of meadow vetchling (Lathyrus pratensis L.) seeds was achieved after scarification with H<sub>2</sub>SO<sub>4</sub> and cultivation in MS medium. The seedlings were used as a material for micropropagation. Regeneration passed through nodal segments cultivated on basal MS medium solidified with a combination of agar and phytagel. This culture medium was also suitable for the plant maintenance. An addition of cytokinin to the induction medium did not support multiplication and growth. In the basal MS medium rooted 72.5% (gene resource 62) or 42.5% (gene resource 28) of shoots. The rooting of gene resource 28 was increased to 63% by the addition of indolylbutyric acid to the culture medium. The regenerated plants were successfully transferred to the soil. This protocol can be used to rescue gene resources of this species.    

Pharmacological evidence for a positive influence of the cyclic GMP-independent transduction on the cyclic GMP-mediated Ca 2+-dependent pathway within Arabidopsis stomatal opening in response to auxin

It has been suggested that, besides cyclic GMP (cGMP)-mediated Ca 2+ signaling, Ca 2+ independence characterized the cGMP-independent auxin transduction. The present study searched for how cGMP-mediated and cGMP-independent pathways cooperated. For this purpose, the plant growth temperature (GT), which acted on the Ca 2+ status of stomatal movements, was manipulated in a pharmacological comparison of Arabidopsis stomatal opening to either the auxin, indolyl-3-butyric acid (IBA) or to the cGMP membrane-permeating derivative, 8-bromoguanosine 3′,5′-cyclic monophosphate (8-Br-cGMP). The Ca 2+ buffer 1,2-bis( o-aminophenoxy)ethane- N, N, N′, N′-tetraacetic acid (BAPTA or its acetoxymethyl ester, BAPTA-AM) inhibited the IBA response by 70%, whereas it completely inhibited the 8-Br-cGMP response at the 23–25 °C GT range. Stomatal opening to IBA, but not to 8-Br-cGMP, was insensitive to BAPTA or BAPTA-AM at the 15–17 °C GT range. The 8-Br-cGMP response was insensitive to the guanylyl cyclase inhibitor, 6-anilino-5,8-quinolinedione (LY 83583), the inactive mastoparan analogue, mas17 and the GTP-binding protein (G-protein) antagonist, pGlu–Gln– d-Trp–Phe– d-Trp– d-Trp–Met–NH 2 (GP Ant-2) at the 23–25 and 15–17 °C GT ranges. These three compounds suppressed the IBA response by 70% at the 23–25 °C GT range, whereas only GP Ant-2 was effective at the 15–17 °C GT range. Moreover, the G-protein activator mas7 counteracted mas17 but not GP Ant-2 at the 23–25 °C GT range. Together, these results suggested that cGMP-mediated and cGMP-independent auxin transductions implicated G-protein regulation, upon which GT acted. Furthermore, they allowed me to suppose that the cGMP-independent transduction positively influenced the cGMP-mediated pathway via a yet to be identified interaction between at least two G-proteins upstream or at the level of cGMP synthesis.

Carbon dioxide and ferricyanide parallel each other to inhibit Commelina stomatal opening in a putative Ca 2+-independent fashion

Summary It has been suggested that both CO2 and the non-permeating electron acceptor ferricyanide (FeCN) inhibit stomatal opening through interfering with guard cell proton extrusion. Whether the CO2 and FeCN inhibitory effects result from a common process was studied by comparing these effects in epidermal peels of Commelina communis (L.). Phenylarsine oxide (PAO) inhibited stomatal opening in response to fusicoccin (FC) and the auxin, indolyl-3-butyric acid (IBA), but not in response to the membrane-permeable derivative of the auxin putative second messenger, 8-bromoguanosine 3′,5′-cyclic monophosphate (8-Br-cGMP). Since PAO has been previously shown to inhibit FC-induced allosteric activation of the plant plasma membrane H+-ATPase from the low-activity state to the high-activity state, the H+-ATPase activity state could be high in response to FC or IBA, but not in response to 8-Br-cGMP. CO2 and FeCN paralleled each other through extent and kinetics of their inhibition of stomatal opening. When added 1 h before applying either FC, IBA or 8-Br-cGMP, the H+-ATPase activator, butyric acid, removed the CO2 and FeCN inhibitory effects. These CO2 and FeCN effects were higher on the 8-Br-cGMP response and, only in this case, pretreating the peels with FC removed them. Together, these results show a close parallel between CO2 and FeCN in inhibiting stomatal opening. They were discussed on the basis of a possible competition for reducing power between the functioning of an electrogenic plasma membrane H+-ATPase and CO2 fixation or FeCN reduction. Such a competition would agree with a Ca2+-independent inhibition of stomatal opening, which was pharmacologically supported by the fact that the CO2 and FeCN inhibitory effects were not modified by the potent Ca2+ buffer 1,2-bis(o-aminophenoxy)ethane-N,N,N ′,N ′-tetraacetic acid.

Pharmacological evidence for the implication of both cyclic GMP-dependent and -independent transduction pathways within auxin-induced stomatal opening in Commelina communis (L.)

It has been previously suggested that auxin-induced stomatal opening results from at least two transduction pathways, one of which involves cyclic GMP (cGMP) as the mediator within a Ca 2+ signalling cascade. This hypothesis was investigated further in epidermal peels of Commelina communis by comparing the effects of potential inhibitors of plant Ca 2+-dependent enzymes on the stomatal opening responses to the auxin indolyl-3-butyric acid (IBA) and to the cGMP membrane-permeable derivative 8-bromoguanosine 3′,5′-cyclic monophosphate (8-Br-cGMP). In the 30–50 μM range, the potential plant calmodulin (CaM) antagonist N-(aminohexyl)-5-chloro-1-naphthalenesulphonamide (W-7) positively interacted with IBA but not with 8-Br-cGMP to open the stomata. The CaM antagonists W-7 (in the 10–20 μM range) and N-(aminohexyl)-1-naphthalenesulphonamide (40 μM), the potential inhibitors of plant protein kinases 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (20 and 200 μM) and K-252a (0.6 μM), and cyclosporine A and FK506, potential inhibitors of plant homologs of Ca 2+–CaM complex (Ca 2+/CaM)-dependent protein phosphatase 2B, prevented the IBA and 8-Br-cGMP responses by about 70% and 100%, respectively. Together, these results provide indirect pharmacological evidence that, in addition to the cGMP-dependent pathway, the auxin signal is transduced through at least one cGMP-independent pathway.

A Simple Procedure for Synthesis of Roxindole, a Dopamine D2-Receptor Agonist

A modified convenient and high yielding synthetic route for the preparation of the dopamine agonist roxindole 1 is described. The key step in our method is the phase-transfer catalyzed reaction of gamma-butyrolactone with 5-methoxyindole which results in the indolylbutyric acid derivative directly in one step.

A simple procedure for synthesis of roxindole, a dopamine D2-receptor agonist.

A modified convenient and high yielding synthetic route for the preparation of the dopamine agonist roxindole 1 is described. The key step in our method is the phase-transfer catalyzed reaction of gamma-butyrolactone with 5-methoxyindole which results in the indolylbutyric acid derivative directly in one step.

Uso de ágar, amido e ácido indolbutírico no enraizamento in vitro do porta-enxerto de macieira MM 111

O ágar é um dos componentes mais caros do meio de propagação in vitro. Visando a reduzir custos, os estudos foram desenvolvidos no Laboratório de Cultura de Tecidos da EMBRAPA/CPACT, Pelotas RS, objetivando-se testar a ação do ágar e da sua substitução parcial pelo amido de mandioca na composição do agente solidificante (AS) do meio MS, associados às concentrações de 0; 2,5; 5,0; 7,5 e 10µM de ácido indolbutírico (AIB). Os dois AS de meio de cultivo testados: AS1 - 6g/l de ágar e; AS2 - combinação de 3g/l de ágar mais 50g/l de amido de mandioca (fécula), tiveram redução de Vi dos sais de MS e acréscimos de 100mg/l de mio-inositol e 30g/l de sacarose, juntamente com pH ajustado em 5,9 antes da autoclavagem. Os explantes foram mantidos por 30 dias em sala de crescimento sob condições de 25±2°C, 16 horas de fotoperíodo e ±2000lux de intensidade luminosa. O AS2, além de apresentar o maior número de raízes, e maximizá-las na presença de 5µM de AIB, antecipou em cerca de 10 dias o surgimento destas e apresentou consistência semelhante ao AS1, sendo apenas menos transparente.

Micropropagation of rubber trees (Hevea brasiliensis Muell. Arg.)

Tissue cultures were established from newly expanded leaves and axillary buds of rubber trees (Hevea brasiliensis Muell. Arg.). Calli formed from these explants, but no regeneration occurred. Shoots were obtained from axillary buds cultured on Murashige and Skoog's (MS) medium (Physiol. Plant. 15: 473-497, 1962) supplemented with 1.0 mg/l kinetin, 1.0 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D), 20 g/l sucrose and 4 g/l Difco agar. Formation of a root similar to a tap root was induced on MS medium supplemented with 5.0 mg/l naphthaleneacetic acid (NAA), 3.0 mg/l indolylbutyric acid (IBA), 50 g/l sucrose and 4 g/l Difco agar. Several types of explants were used in attempts to recover complete rubber tree plants with well-developed tap roots. Leaf explants and axillary buds formed calli on MS basic medium with different combinations of kinetin, benzylaminopurine (BAP), 2,4-D, IBA, NAA and indolylacetic acid (IAA). The antibiotic tetracycline was also used to control possible bacterial infections. However, no antibiotic effect was noted. Calli formation was abundant, but no regeneration was observed when the calli from different media was transferred to MS medium without growth hormones. On this basic medium, callus cultures became necrotic and died. Shoots developed from axillary buds, rooted vigorously when cultured on MS medium with NAA, IAA, and IBA. Based on these results, further studies with commercially important clones should lead to a feasible micropropagation technique.

Putative involvement of cytosolic Ca 2+ and GTP-binding proteins in cyclic-GMP-mediated induction of stomatal opening by auxin in Commelina communis L.

To investigate whether cyclic GMP (cGMP) would mediate, in an intracellular Ca2+ -dependent manner, coupling of auxin to stomatal opening, the stomatal opening responses to the auxin indolyl-3-butyric acid (IBA) and to the cGMP membrane-permeable derivative 8-bromoguanosine 3′,5′-cyclic monophosphate (8-Br-cGMP) were compared in epidermal strips of Commelina communis. In this comparison were studied possible effects of intracellular Ca2+ modulators, GTP-binding protein (G-protein) modulators and selective inhibitors of enzymatic reactions which use or generate cGMP. The stomatal response to IBA was almost similarly reversed by the Ca2+ buffer 1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid (BAPTA), the intracellular Ca2+-release inhibitors ruthenium red and procaine, the inactive cGMP analog Rp-8-bromoguanosine 3′,5′-cyclic monophosphorothioate (Rp-8-Br-cGMPS), the inhibitor of cGMP-producing guanylyl cyclase LY 83583, the G-protein inhibitor mas17 and the G-protein antagonist pGlu-Gln-D-Trp-Phe-D-Trp-D-Trp-Met-NH2. Comparison with stomatal opening in response to 8-Br-cGMP, which was almost completely suppressed by either BAPTA, ruthenium red, procaine or Rp-8-Br-cGMPS, strongly suggests that cGMP acts downstream of G-protein activation as a second messenger for IBA signal transduction and that the cGMP pathway likely depends on cytosolic Ca2+signaling.

Micellar liquid chromatography of plant growth regulators detected by derivative fluorometry

A micellar liquid chromatographic method with fluorimetric detection was developed for the determination of the plant growth regulators indol 3-yl acetic acid (IAA), 2-(1-naphthyl) acetic acid (1-NAA), indol 3-yl propionic acid (IPA), 2-(2-naphthyl) acetic acid (2-NAA), indol 3-yl butyric acid (IBA), 2-(1-naphthyl) acetamide (1-Namide) and indol 3-yl acetic acid ethyl ester (IAA ethyl ester). Extraction of plant hormones was performed with methanol, followed by purification with ethyl acetate, solid-phase extraction and again partitioning against diethyl ether. Sodium dodecylsulphate (10 m M) is used as mobile phase to elute the compounds in a maximum run-time of 23 min. Partially or unresolved peaks are separated by calculation of the 1st derivative chromatogram. Detection limits are between 0.30 μg g −1 and 1.10 μg g −1.