Gas-Liquid Chromatographic Isolation of Cytokinins from Natural Sources: 6-(3-Methyl-2-butenylamino) purine from Agrobacterium Tumefaciens

Phenotypic and molecular characterisation of efficient nitrogen-fixing Azotobacter strains from rice fields for crop improvement

Biological nitrogen fixation (BNF) is highly effective in the field and potentially useful to reduce adverse effects chemical fertilisers. Here, Azotobacter species were selected via phenotypic, biochemical and molecular characterisations from different rice fields. Acetylene reduction assay of Azotobacter spp. showed that Azotobacter vinelandii (Az3) fixed higher amount of nitrogen (121.09 nmol C2H4 mg(-1) bacteria h(-1)). Likewise, its plant growth functions, viz. siderophore, hydrogen cyanide, salicylic acid, IAA, GA3, zeatin, NH3, phosphorus solubilisation, ACC deaminase and iron tolerance, were also higher. The profile of gDNA, plasmid DNA and cellular protein profile depicted inter-generic and inter-specific diversity among the isolates of A. vinelandii. The PCR-amplified genes nifH, nifD and nifK of 0.87, 1.4 and 1.5 kb , respectively, were ascertained by Southern blot hybridisation in isolates of A. vinelandii. The 16S rRNA sequence from A. vinelandii (Az3) was novel, and its accession number (JQ796077) was received from NCBI data base. Biofertiliser formulation of novel A. vinelandii isolates along with commercial one was evaluated in rice (Oriza sativa L. var. Khandagiri) fields. The present finding revealed that treatment T4 (Az3) (A. vinelandii) are highly efficient to improved growth and yield of rice crop.

Isolation of cis-Zeatin from Corynebacterium fascians Cultures

Three cytokinin-active constituents have been isolated from the culture medium of Corynebacterium fascians, a plant pathogen causing fasciation. One constituent is now identified as cis-zeatin [6-(4-hydroxy-3-methyl-cis-2-butenylamino)purine]. It represents the first unequivocal demonstration of the production of a zeatin isomer by a bacterial species. Another constituent was identified earlier as 6-(3-methyl-2-butenyl-amino)purine. The third constituent, distinct, on Sephadex LH-20 column chromatography, from the above two and their ribosides, has not yet been identified.

Ribosyl-trans-Zeatin, A Major Cytokinin Produced by Crown Gall Tumor Tissue

A cell division factor in crystalline form has been isolated from ethanolic extracts of cultured Vinca rosea L. crown gall tumor tissue. The crystalline material shows the melting point, mass spectrum, ultraviolet-light absorbancy spectra, solubilities, chromatographic migration values, ion-exchange behavior, and growth activities expected of ribosyl-trans-zeatin, that is, 6-(4-hydroxyl-3-methyl-trans-2-butenylamino)-9-beta-D- ribofuranosylpurine. This compound, which appears to be a major cell-division factor in the extracts, has also been crystallized from liquid media in which the tumor tissue had been growing and apparently was the only active compound in such media.

Evaluation of selective detectors for the rapid and sensitive gas chromatographic assay of cytokinins, and application to the analysis of cytokinins in plant extracts

The performances of four gas chromatographic detectors (nitrogen-phosphorus, flamephotometric, electron-capture and flame-ionisation) were compared for the analysis of permethylated cytokinins. The nitrogen-phosphorus and flame-photometric detectors (selective for nitrogen and sulphur-containing compounds respectively) gave greatly enhanced sensitivity and-or specificity compared with the flame-ionisation detector for a wide range of cytokinin types. The response of the electron-capture and flame-ionisation detectors was quantitatively similar. The improved performance of the nitrogen-phosphorus and flame-photometric detectors was used to develop rapid and simple purification techniques for the assay of zeatin and zeatin riboside in coconut milk; dihydrozeatin and dihydrozeatin riboside in bean leaves and cytokinin nucleosides in wheat-germ transfer RNA.

Radioimmunoassays for trans-zeatin and related cytokinins

Radioimmunoassays for the quantitation of trans-zeatin and related cytokinins have been developed. Antisera produced against bovine serum albumin conjugates of trans-zeatinriboside have a high affinity (Ka=2.4.10(-11) M) for zeatinriboside and for zeatin, but show a negligible cross reaction to isopentenyladenosine (0.1%) and cis-zeatinriboside (0.4%), only a slight cross reaction to dihydrozeatin (1.7%), and no cross reaction at all to other purines, such as adenosine and related, compounds, was observed. The assays are sensitive and measuring ranges extend from 0.06-30 pmol (0.02-10 ng) of zeatinriboside. This has been achieved by employing as tracers immunoreactive zeatin derivatives with high-specific activity, (tritiated zeatinriboside-dialcohol: 8.37.10(11) Bq mmol(-1) and zeatinribosyl-[(125)I]tyramine: ca. 1.9.10(13) Bq mmol(-1). The detection limit is 40 fmol (15pg) for the assay employing the tritiated tracer, and assay reproducibility is high (variation coefficients of triplicates less than 5%). Several hundred assays can be completed in one day, and, due to the high specificity of this assay, crude extracts may be used for analysis. The course of zeatin levels in developing fruits of Lycopersicon esculentum cv. Moneymaker is given.

Kinetin incorporated into tobacco callus ribosomal RNA and transfer RNA preparations

Kinetin, N(6)-furfuryladenine, was incorporated into tobacco (nicotiana tabacum L., var. Wis. No. 38) callus RNA isolated from rapidly growing tissue cultured in the presence of N(6)-furfuryladenine-8-(14)C or unlabeled kinetin. Approximately 0.7% of the radioactivity in the labeled kinetin added to the medium was recovered as N(6)-furfuryladenosine (fr(6)A) in the rRNA and tRNA preparations from the tobacco callus. The rRNA contained over 90% of these fr(6) A moieties. The extent of kinetin incorporation was four times greater than that observed for N(6)-benzyladenine. The radiochemical purity of the recovered fr(6) A was confirmed by three successive chromatographic purifications on Sephadex columns (LH-20 eluted with 35% ethanol, G-10 eluted with 20% ethanol, and LH-20 eluted with water). A cytokinin-active ribonucleoside with elution volumes corresponding to fr(6) A was isolated from the tobacco callus rRNA preparation. This compound was analyzed by gas-liquid chromatography and rigorously characterized as N(6)-furfuryladenosine by gas-liquid chromatography-mass spectrometry of the trimethylsilyl derivative.

Purification and identification of a cytokinin from moss callus cells

A cytokinin was isolated from the culture medium of callus cells of the moss hybridFunaria hygrometrica (L.) Sibth xPhyscomitrium piriforme Brid. The purification procedure included ethyl-acetate extraction, silver-salt precipitation, crystallization as picrate, and ion exchange chromatography. The structure of the cytokinin was confirmed as N(6)-(Δ(2)-isopentenyl)adenine by means of gas chromatography and mass spectrometry. The concentration of the compound in the culture medium was determined at ca. 10(-6) M.

Cytokinins in Corynebacterium fascians Cultures: Isolation and Identification of 6-(4-Hydroxy-3-methyl-cis-2-butenylamino)-2-methylthiopurine

In addition to the four cytokinins, 6-(3-methyl-2-butenylamino)purine, 6-methylaminopurine and the cis and trans isomers of 6-(4-hydroxy-3-methyl-2-butenylamino)purine, reported earlier from our laboratories, three cytokinin-active fractions have been obtained from the aqueous medium of 6-day-old Corynebacterium fascians cultures. One of these has been identified as 6-(4-hydroxy-3-methyl-cis-2-butenylamino)-2-methylthiopurine (2-methylthio-cis-zeatin, c-ms(2)io(6) Ade).The elution volumes of the other two fractions correspond to those of authentic 6-(4-hydroxy-3-methyl-2-butenylamino)-9-beta-d-ribofuranosyl-purine and 6-(3-methyl-2-butenylamino)-9-beta-d-ribofuranosylpurine, indicating the presence of trace amounts of these two ribonucleosides.

Products of soil microorganisms in relation to plant growth

A survey has been made of the range and activity of the organic products of soil microorganisms which have a direct influence on plant growth. Microbial metabolites which effect plants indirectly by the modification of the soil environment are also reviewed. The sources of substrates for the production of metabolites in soil and the farming practices which give rise to them are considered. It is stressed that an interdisciplinary approach is needed in the manipulation of microbiological activity in soil.

Developmental Effects of Zeatin, Ribosyl-Zeatin, and Agrobacterium tumefaciens B(6) on Certain Mosses

Eight species of mosses studied were divided into two groups on the basis of their developmental responses to ribosyl-trans-zeatin and Agro-bacterium tumefaciens B(6). All eight produced either gametophores or callus on the protonema in response to 6-(gamma,gamma-dimethylallylamino) purine and trans-zeatin. Three which produced normal gametophores with A. tumefaciens yielded callus or abnormal gametophores with ribosyl-trans-zeatin. Ribosyl-trans-zeatin and A. tumefaciens were relatively ineffective on five other mosses. Characteristics of protonemal growth common to each of these two groups are described.

Cytokinins of sycamore spring sap

The cytokinins present in the spring sap of Acer pseudoplatanus L. were investigated. Ribosyl-trans-zeatin, trans-zeatin and dihydrozeatin were isolated and identified by combined gas chromatography-mass spectrometry (GC-MS). A number of other cytokinin active fractions were observed. One of these was less polar than zeatin and did not behave as any known cytokinin. Two other fractions were more polar than ribosylzeatin and were unstable. A decomposition product of one of these was identified as ribosyl-trans-zeatin by GC-MS. The possible nature of the unstable compounds is discussed. Data on the changes in cytokinin activity of the various fractions during spring 1973 are presented and discussed.

A simple, inexpensive, high pressure liquid chromatographic method for separating cytokinins in plant extracts

Separation of a mixture of the main cytokinins occurring naturally in plant tissues was achieved by high pressure liquid chromatography using insoluble polyvinylpyrrolidone as the solid support. The separation of each cytokinin was first assessed over a range of salt and l-butanol concentrations and pH using a mixture of borate buffer and l-butanol as the mobile phase to determine the conditions necessary for optimum resolution. A discrete separation of zeatin, N-6-(Delta-2-isopentenyl)adenine, their related ribonucleosides, and kinetin was achieved using a simple isocratic elution with 0.025 m borate buffer at pH 6.8 and 4% (v/v) l-butanol. A number of cytokinin-active compounds were detected in cabbage extracts by the Amaranthus betacyanin bioassay using this separation technique.

Identification of plant hormones from cotton ovules

An extract from 8-day-old cotton ovules (Gossypium hirsutum L.) was partitioned into three fractions and each fraction was derivatized and analyzed separately. Gas-liquid chromatography and computer-controlled gas-liquid chromatography-mass spectrometry were used to separate, measure, and identify the naturally occurring plant hormones. A single extract contained abscisic acid, indoleacetic acid, and gibberellins A(1), A(3), A(4), A(7), A(9), and A(13) in the first fraction; ethyl indole-3-acetate and indole-3-aldehyde in the second fraction; and the cytokinins 6-(3-methyl-4-hydroxybutylamino)purine (dihydrozeatin), 6-(4-hydroxy-3-methyl-2-trans-butenylamino) purine (zeatin), 6-(3-methyl-2-butenylamino)purine(2iP), 6-(3-methyl-2-butenylamino)-9-beta-d-ribofuranosylpurine(2iPA), and 6-(4-hydroxy-3-methyl-2-trans-butenylamino)-9-beta-d- ribofuranosylpurine (zeatin riboside) in the third fraction.

N-(Delta-Isopentenyl)adenosine: Its Occurrence as a Free Nucleoside in an Autonomous Strain of Tobacco Tissue

Cytokinins from both the free nucleoside pool and the transfer RNA have been isolated and identified in a habituated strain of tobacco pith callus (Nicotiana tabacum [L] var. Wisconsin 38). The transfer RNA of this strain contains both N(6)-(Delta(2)-isopentenyl) adenosine and N(6)-(4-hydroxy-3-methylbut-2-cis-enyl) adenosine. The trans-hydroxylated derivative is absent from the transfer RNA of this dark-grown tissue. N(6)-(Delta(2)-Isopentenyl)-adenosine was identified as a component of the free nucleoside pool in concentrations of about 10 micrograms per kilogram of tissue.The cytokinin-requiring tissue grown in the presence of N(6)-furfurylaminopurine contains less than 85 nanograms per kilogram of N(6)-(Delta(2)-isopentenyl) adenosine. This is the detectable limit under the conditions of the experiment.

Limitation of tobacco callus tissue growth by carbohydrate availability

Growth rate, maximum dry weight yield, and carbohydrate utilization were measured with pith callus derived from Nicotiana tabacum L. var. Wisconsin No. 38. Maximum tissue dry weights increased as carbohydrate (either glucose or sucrose) in the medium was increased. The time at which maximum growth was obtained coincided with the time at which carbohydrate was exhausted from the medium. The addition of carbohydrate to the medium before the end of log phase growth supported that amount of additional growth which would have been obtained if all of the carbohydrate had been added to the medium prior to planting the tissue. Maximum obtainable dry weights at logarithmic growth rates greater than 0.16 doubling per day depended on the amount of carbohydrate in the medium and not on a particular hormonal regime.