Abscisic acid content of salt-stressed Phaseolus vulgaris L

Engineering Lignin Nanomicroparticles for the Antiphotolysis and Controlled Release of the Plant Growth Regulator Abscisic Acid

Lignin is the most abundant aromatic biopolymer in nature and is a major byproduct from the paper industry. The unlocking of lignin's potential for high-value applications has gained increasing attention in recent years. In this study, alkali lignin (AL), with a rigid conjugated structure and amphiphilic property, was used as a sustainable and eco-friendly encapsulation material for the protection and controlled release of photosensitive abscisic acid (ABA), an important and widely used plant growth regulator. Cetyltrimethylammonium bromide (CTAB) was used to induce the formation of AL-CTAB nanomicroparticles by self-assembly. The size and morphology of AL-CTAB particles were modified by changing the AL concentration and the dispersion agent. AL (0.3 M) dissolved in tetrahydrofuran could form a uniform size (300 nm) of particles with a regular spherical structure. Subsequently, ABA was loaded on the prepared nanomicroparticles to synthesize the capsule formulation of ABA@AL-CTAB. The controlled-release behavior and the antiphotolysis performance as well as the thermal stability of ABA@AL-CTAB were proved to be superior. Lasting inhibition of Arabidopsis and rice seed germination by ABA@AL-CTAB under light irradiations implied protection of ABA from photolysis. In addition, ABA@AL-CTAB could effectively regulate plant stomata, thereby increasing plant drought resistance. Overall, lignin is suitable for the preparation of agrochemical formulations with excellent controlled release and antiphotolysis performances.

Determination of chiral jasmonates in flowers by GC/MS after monolithic material sorptive extraction

A GC/MS method with monolithic material sorptive extraction (MMSE) pretreatment was developed to determine contents of the enantiomers of jasmonic acid and methyl jasmonate in flowers. To optimize MMSE extraction, several MMSE parameters were investigated, including extraction temperature, extraction time, and extraction solvent. Under the optimal conditions, extraction efficiency was good. Using the selected-ion monitoring mode, the limit of detection (LOD, S/N = 3) for methyl jasmonates was 0.257 ng/mL. The limit of quantitation (LOQ, S/N = 10) was 0.856 ng/mL. The linearity range was 1-100 ng/mL. The average recovery of methyl jasmonate at lower concentration was 116.8% (2 ng/mL). The relative standard deviation of methyl jasmonate contents determined within the linear range of detection was less than or equal to 15% of the mean determined level. The proposed method is rapid, sensitive, and competently applied to the determination of jasmonic acid and methyl jasmonate enantiomers in flowers.

Profiling ABA metabolites in Nicotiana tabacum L. leaves by ultra-performance liquid chromatography-electrospray tandem mass spectrometry

We have developed a simple method for extracting and purifying (+)-abscisic acid (ABA) and eight ABA metabolites--phaseic acid (PA), dihydrophaseic acid (DPA), neophaseic acid (neoPA), ABA-glucose ester (ABAGE), 7'-hydroxy-ABA (7'-OH-ABA), 9'-hydroxy-ABA (9'-OH-ABA), ABAaldehyde, and ABAalcohol--before analysis by a novel technique for these substances, ultra-performance liquid chromatography-electrospray ionisation tandem mass spectrometry (UPLC-ESI-MS/MS). The procedure includes addition of deuterium-labelled standards, extraction with methanol-water-acetic acid (10:89:1, v/v), simple purification by Oasis((R)) HLB cartridges, rapid chromatographic separation by UPLC, and sensitive, accurate quantification by MS/MS in multiple reaction monitoring modes. The detection limits of the technique ranged between 0.1 and 1 pmol for ABAGE and ABA acids in negative ion mode, and 0.01-0.50 pmol for ABAGE, ABAaldehyde, ABAalcohol and the methylated acids in positive ion mode. The fast liquid chromatographic separation and analysis of ABA and its eight measured derivatives by UPLC-ESI-MS/MS provide rapid, accurate and robust quantification of most of the substances, and the low detection limits allow small amounts of tissue (1-5mg) to be used in quantitative analysis. To demonstrate the potential of the technique, we isolated ABA and its metabolites from control and water-stressed tobacco leaf tissues then analysed them by UPLC-ESI-MS/MS. Only ABA, PA, DPA, neoPA, and ABAGE were detected in the samples. PA was the most abundant analyte (ca. 1000 pmol/g f.w.) in both the control and water-stressed tissues, followed by ABAGE and DPA, which were both present at levels ca. 5-fold lower. ABA levels were at least 100-fold lower than PA concentrations, but they increased following the water stress treatment, while ABAGE, PA, and DPA levels decreased. Overall, the technique offers substantial improvements over previously described methods, enabling the detailed, direct study of diverse ABA metabolites in small amounts of plant tissue.

Study on the extraction, purification and quantification of jasmonic acid, abscisic acid and indole-3-acetic acid in plants

INTRODUCTION

Jasmonic acid (JA), abscisic acid (ABA) and indole-3-acetic acid (IAA) are important plant hormones. Plant hormones are difficult to analyse because they occur in small concentrations and other substances in the plant interfere with their detection.

OBJECTIVE

To develop a new, inexpensive procedure for the rapid extraction and purification of IAA, ABA and JA from various plant species.

METHODOLOGY

Samples were prepared by extraction of plant tissues with methanol and ethyl acetate. Then the extracts were further purified and enriched with C(18) cartridges. The final extracts were derivatised with diazomethane and then measured by GC-MS. The results of the new methodology were compared with those of the Creelman and Mullet procedure.

RESULTS

Sequential elution of the assimilates from the C(18 )cartridges revealed that IAA and ABA eluted in 40% methanol, while JA subsequently eluted in 60% methanol. The new plant hormone extraction and purification procedure produced results that were comparable to those obtained with the Creelman and Mullet's procedure. This new procedure requires only 0.5 g leaf samples to quantify these compounds with high reliability and can simultaneously determine the concentrations of the three plant hormones.

CONCLUSION

A simple, inexpensive method was developed for determining endogenous IAA, ABA and JA concentrations in plant tissue.

Determination of endogenous and supplied deuterated abscisic acid in plant tissues by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry with multiple reaction monitoring

A specific, sensitive, and accurate method for determination of abscisic acid (ABA) in plant tissues is described. The method employs reversed-phase high-performance liquid chromatography and electrospray ionization-tandem mass spectrometry for multiple reaction monitoring of underivatized ABA and deuterated ABA analogs. Specific analogs were used to study the mechanism of ABA fragmentation, to select appropriate standards, and to identify compounds suitable for metabolic studies involving the supply of differentially labeled ABA. Limits of detection and quantification of 1.9 and 4.7 pg, respectively, were obtained over a linear calibration range of 0-1.5 ng ABA (on-column injected) using 5.8', 8', 8'-d(4) ABA as the internal standard. Accuracy and precision were within 15% for routine quality control samples. The method of standard additions, as applied to Arabidopsis thaliana seed extracts, was also used to validate the method for analysis of plant tissue samples. The utility of the method was further demonstrated by determining levels of ABA in western white pine seeds and of ABA and supplied 8', 8', 8', 9', 9', 9'-d(6) ABA in Brassica napus tissues, using 5.8', 8', 8'-d(4) ABA or 8', 8', 8'-d(3) ABA as the internal standard. Limits of quantification as low as 0.89 ng/g were achieved by optimizing the extraction procedure for each type of plant tissue.

Determination of abscisic acid by capillary electrophoresis with laser-induced fluorescence detection

A novel method based on capillary electrophoresis coupled to laser-induced fluorescence detection (CE-LIF) was developed for the determination of abscisic acid (ABA), which is an essential phytohormone during plant growth and development. ABA was labeled with 8-aminopyrene-1,3,6-trisulfonate via reductive amination in presence of acetic acid and sodium cyanoborohydride. The derivatization yield was maximized by optimizing several derivatization parameters including derivatization reagent concentration, reaction temperature and time. The conjugate was separated and quantitated by CE-LIF. The linearity of ABA was determined in the range from 0.1 to 10 micromol l(-1) with a correlation of 0.9979. The derivatization limit of detection for ABA was found to be 56 fmol (corresponding to the concentration of 2.8 x 10(-8) mol l(-1)). The detection limit for ABA was 5.5 amol for an injection volume of 5 nl. As a preliminary application, the proposed method was successfully applied to determining trace amount of ABA in the crude extracts of tobacco without extra purification and enrichment procedure and showed a better selectivity and sensitivity than those conventional methods used in determination of ABA.

Efficient leaf ion partitioning, an overriding condition for abscisic acid-controlled stomatal and leaf growth responses to NaCl salinization in two legumes

Two tree medics contrasting in salt tolerance, Medicago arborea and Medicago citrina, were compared to evaluate the relative importance of abscisic acid on leaf growth and stomatal responses to salt stress. Plants were grown for 30 d in solution culture with 1, 50, 100 or 200 mM NaCl. Salinized plants of M. citrina had lower Na+ and Cl- uptake and maintained better leaf growth than M. arborea. In M. citrina, stomatal conductance was only slightly affected by salt and, in consequence, the salt treatment had no significant influence, neither on the CO2 fixation rate nor the transpiration rate in these plants. Moreover, leaf photosynthetic pigments and soluble protein in M. citrina were increased by the presence of NaCl, while a decrease of both parameters with salt was found in M. arborea. However, leaf and xylem ABA increased only in salt-treated M. citrina, while no differences were found among treatments in M. arborea. The role of ion compartmentation, gas exchange parameters and ABA concentrations in relation to salt tolerance in M. arborea and M. citrina is discussed.