Characterization of indole-3-acetic acid in cambial zone tissue by ultra-performance liquid chromatography-tandem mass spectrometry

The developmental plasticity of plants according to changes in their growth conditions is mediated by signalingmolecules called hormones. The major classes of plant hormones are auxin, gibberellins, abscisic acid, andethylene. Among these, the most important is indole-3-acetic acid (IAA). Quantification of IAA in an extract ofapproximately 10 mg obtained from the cambial zone of Eucalyptus leaves was performed by ultra-performanceliquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC/ESI-MS/MS). Theleaves were extracted using acetone, and the extract was analyzed using a reverse-phase column (Acquity UPLCBEH C18, 2.1 mm × 100 mm, 1.7 µm) at a flow rate of 0.2 mL/min with gradient elution of an aqueous mobile phase(containing 0.1% formic acid) with methanol. This gradient elution provided an excellent performance in terms ofspecificity/selectivity, linearity, precision, and ruggedness/stability. In addition, the run time was short (6 min), withexcellent linearity (R2 > 0.99) in the range of 10–70 ng/mL. The structure of IAA was elucidated using UPLC/ESIMS/MS, operating and quantifying in multiple reaction monitoring (MRM) mode.

Isolation and identification by 16S rRNA sequence analysis of plant growth-promoting azospirilla from the rhizosphere of wheat

ABSTRACT The main objective of the present study was to isolate phytohormone-producing, phosphate-solubilizing strains of Azospirillum from wheat to be used as inoculants for plant growth promotion. Five Azospirillum strains were isolated from the rhizosphere of field-grown wheat (Triticum aestivum L.), and it was confirmed by BOX-polymerase chain reaction (PCR) that the isolates were different and not re-isolates of the same strain. Sequence analysis of the PCR-amplified 16S rRNA gene indicated that four isolates showed maximum similarity to Azospirillum brasilense and one isolate showed maximum similarity to Azospirillum zeae. This is the first report indicating the presence of an A. zeae like isolate in the wheat rhizosphere in Pakistan. The bacterial isolates were characterized for their plant growth-promoting traits, phosphate solubilization, and indole-3-acetic acid (IAA) production. None of the isolates showed phosphate solubilization activity in the commonly used Pikovskaya medium. However, all strains (except AzoK4) exhibited ability to solubilize tricalcium phosphate (TCP) in modified Pikovskaya medium in which sucrose was replaced by Na-malate, as well as in TCP-supplemented Luria-Bertani (LB) medium. Organic acids, such as acetic, citric, lactic, malic, and succinic acids, were detected in culture supernatants of the tested Azospirillum strains. All strains exhibited ability to produce IAA in the growth medium, except Azospirillum sp. AzoK1. Among the strains tested, the maximum IAA production (30.49 ± 1.04 mg L-1) and phosphate solubilization (105.50 ± 4.93 mg L-1) were shown by a pure culture of Azospirillum sp. AzoK2. In pot experiments, single-strain inocula of Azospirillum sp. AzoK1 and AzoK2 improved wheat plant growth.

Effects of exogenous hormones on growth and tanshinones accumulation in radix of Salvia miltiorrhiza / 中草药

Objective To study the effects of exogenous hormones,gibberellin(GA3)and indole-3-acetic acid(IAA),on growth and tanshinones accumulation in the radix of Salvia miltiorrhiza.MethodsThe herb characters and contents of tanshinones(cryptotanshinone,tanshinone Ⅰ,and tanshinone ⅡA)in the radix of S.miltiorrhiza with different hormone treatments were investigated and compared in the combination of trail pot and indoor analysis.Results It promoted aboveground biomass in the radix of S.miltiorrhiza increasing with single GA3.But it inhibited underground biomass increasing.The exogenous addition of low-level and high-level GA3 was benefit for tanshinones accumulation,whereas the middle-level GA3 wasn't.The aboveground and underground biomass in the radix of S.miltiorrhiza increased indistinctively with the increasing of IAA concentration and then decreased.And the IAA solutions also increased plant height and root length indistinctively.in a whole,it was benefit for tanshinones accumulation when applying low-level IAA(0.5 mg/L)singly.With the increasing of IAA concentration,the content of cryptotanshinone increased,but the contents of tanshinone Ⅰ and tanshinone ⅡA decreased.It promoted S.miltiorrhiza radix growth and three tanshinones contents increasing obviously with the combined application of two low-level hormones.Conclusion The applying of GA3 and IAA is benefit for the growth and three tanshinones accumulation in the radix of S.miltiorrhiza.