Relative Activities of Some Cytokinin Fractions of Developing Cotton Fruit

Ion-exchange fractionization, paper chromatography, and soybean callus bioassay have partly resolved an apparent discrepancy in the sequence of cytokinin appearance in developing cotton (Gossypium hirsutum L.) fruit compared to the sequence reported in corn (Zea mays L.). Cotton fruit cytokinins were separated into three fractions: A combined n-butanol and ethylacetate extractable fraction comprisedc. 10% of the cytokinin activity, a fraction not retained by a polymethacrylate weakly acidic cation-exchange resin comprised c. 45%, and a fraction that was retained by the resin, c. 45%. The latter fraction differs from cytokinin fractions reported in corn. However, like cytokinin ribonucleotides, its cytokinin activity remains below R_f 0.3 on paper chromatograms developed with water-saturated sec-butanol, thus complicating studies of sequential cytokinin appearance in cotton. An anion-exchange resin did not retain the cytokinin activity of this fraction.     

Changes in indole-3-acetic acid,indole-3-acetic acid oxidase,and peroxidase isoenzymes in the seeds of developing peach fruits

Changes in indole-3-acetic acid (IAA) content of peach (Prunus persica L. Batsch cv. Merry) seeds were followed during fruit development. The highest concentration of IAA, 2.7 g/g fresh weight, was found at the beginning of Stage III of fruit development, approximately 50–60 days after anthesis. The IAA-decarboxylating capacity of crude extracts of seeds was also greatest at 55–60 days after anthesis. Four soluble peroxidase isoenzymes were found on anionic electrophoresis. There were no marked changes in two isoenzymes (R _f 0.23 and 0.51), which were present in all three stages of fruit growth. There was a marked increase in a band atR _f 0.59 between Stages II and III, and a decrease in a band atR _f 0.68 from Stages II to III. Neither band (R _f 0.59 and 0.68) was present at Stage I.     

Cytokinins of the Developing Mango Fruit : Isolation, Identification, and Changes in Levels during Maturation

The cytokinin activity has been isolated and identified from extracts of immature mango (Mangifera indica L.) seeds. The structures of zeatin, zeatin riboside, and N⁶-(Δ²-isopentenyl)adenine riboside were confirmed on the basis of their chromatographic behavior and mass spectra of trimethylsilyl derivatives. Both trans and cis isomers of zeatin and zeatin riboside were also identified by the retention times of high performance liquid chromatography. In addition, an unidentified compound appeared to be a cytokinin glucoside.

The concentration of cytokinins in the panicle and pulp of mango reached a maximum 5 to 10 days after full bloom and decreased rapidly thereafter. The cytokinin level in the seed remained high until the 28th day after full bloom. The quantity of cytokinins in pulp per fruit increased from the 10th day after full bloom, the maximum being attained around the 50th day after full bloom. Similarly, the amount of cytokinins per seed increased from the 10th day after full bloom, reaching a peak on the 40th day and decreasing gradually thereafter.

A high percentage of fruit set in mango was persistently maintained by supplying 6-benzylaminopurine (1.5 × 10³ micromolar) onto the panicle at the anthesis stage and by supplying gibberellic acid (7.2 × 10² micromolar) and naphthalene acetamide (3.1 × 10 micromolar) at the young fruit stage.

     

AUXIN OF TOMATO FRUIT AT DIFFERENT STAGES OF ITS DEVELOPMENT WITH A SPECIAL REFERENCE TO HIGH TEMPERATURE INJURIES

Acidic auxin in tomato fruit at various developmental stageswas examined by paper chromatography and Avena curvature test. Auxin activity of the fruit extracts was detected only in thesame R_f zone as that of authentic IAA with four solvent systems,i.e., isopropanol-ammonium hydroxide-water 10:1:1 v/v, n-butanol-ammoniumhydroxide-water 25:1:5 v/v, ethanol-water 7:3 v/v and n-butanol-aceticacid-water 4:1:1 v/v. Auxin content of fruit was the highest on the seventh day afteranthesis, when the two-celled proembryo began to grow rapidlyand the endosperm consisted of multi-cells. The second peakof auxin activity occurred on the 30th day, when the embryo,which consisted of the cotyledons, hypocotyl, and radicle, finishedits most rapid growth. No auxin activity was detected in theripe fruit. Auxin contents in fruit on the fifth, seventh, and tenth daysafter anthesis were lowered by a 4 hr high temperature treatmentat 40 given 0–3 days after anthesis. The nature of tomato auxin and its possible role in the fruitdevelopment were discussed. (Received June 30, 1966; )     

Cytokinin Activity in Lupinus albus

The cytokinin content of the root exudate and leaves of fruiting white lupin plants (Lupinus albus L.) was investigated at 2 weekly intervals after anthesis of the lowest flower on the primary inflorescence. Up to 8 weeks after anthesis the level of cytokinins in the root exudate increased. However, at 10 weeks after anthesis insufficient sap was produced for analysis. Cytokinins co-eluting with zeatin and zeatin riboside were detected in the root exudate after fractionation on Sephadex LH-20. The cytokinin levels in the mature leaves steadily increased up to 8 weeks after anthesis and thereafter remained relatively constant. Three peaks of activity, co-eluting with zeatin, zeatin riboside and the glucoside cytokinins were recorded in the leaf extracts. The level of glucoside cytokinins in the leaves was high at 8 and 10 weeks after anthesis. Paper chromatography of extracts of fruits collected at 2 weeks after anthesis indicated that as fruit development proceeded there was a build up of cytokinin in this region of the plant. It is suggested that, in the white lupin, the cytokinins translocated to the shoot are accumulated in the leaves and in the fruits and that it is only later when there is a considerable decrease in sap (10 weeks after anthesis) production that a decreasing supply of cytokinins leads to shoot senescence.     

Cytokinin Activity in Lupinus albus L: IV. Distribution in Seeds

Endogenous levels of cytokinin activity were examined in Lupinus albus L. seed at intervals of 2 weeks after anthesis using the soybean callus bioassay. High levels of cytokinin activity per gram seed material were present in the seeds at 2, 4, and 6 weeks after anthesis. The cytokinin activity per gram seed material was low at 8 and 10 weeks after anthesis. Cytokinin activity associated with each seed was greatest at 6 weeks after anthesis. The majority of the activity in the seeds at 4, 6, and 8 weeks after anthesis was in the endosperm. Cytokinin activity was also detected in the testas and embryos at 4, 6, 8, and 10 weeks, and the suspensors at 4 weeks. Column chromatography of extracts of the different seed fractions on Sephadex LH-20 indicated that the cytokinins present coeluted with zeatin, zeatin riboside, and the glucoside cytokinins. It is suggested that cytokinins are accumulated in the seeds and are stored in the endosperm mainly in the form of ribosides and glucosides of zeatin. The reduction in cytokinin activity in the seed coincides with the reduction in endosperm volume and embryo growth and suggests that these compounds are utilized during the course of seed maturation.     

Effects of Short-term Red Radiation and Choline Compounds on Cytokinin Content, Chlorophyll Accumulation and Photomorphogenesis in Wheat Seedlings

Effects of choline compounds (2-chloroethyltrimethylammonium chloride and 2-ethyltrimethylammonium chloride) as well as red radiation (R) pulse on the dynamics of cytokinin changes, growth and chlorophyll (a + b) accumulation were studied during the growth and greening of etiolated wheat seedlings (Triticum aestivum L., var. Mironovskaya-808). The seedlings were grown for 120 h in the dark and then exposed for 72 h to white light. Pre-treatment of caryopses with cholines and pre-irradiation of etiolated seedlings with R inhibited elongation of both coleoptile and first leaf; but the same factors accelerated these growth responses when seedlings were exposed to white light. Chlorophyll (Chl) accumulation and the first leaf appearance from coleoptile were accelerated by the pre-treatments as well. Far-red radiation (FR) reversed all effects of R but choline pre-treatment eliminated partly R/FR photoreversibility. Two compounds with high cytokinin activity (tested on a fresh weight basis by the bioassay with Amaranthus caudatus L.) were found in shoots and first leaves. One of them had R_f, UV absorbance spectrum and the biological activity similar to N⁶-(Δ²-isopentenyl)adenosine. Another cytokinin-like substance was not identified with the used standards. Stimulation of greening by R pulse and cholines was accompanied with accelerated accumulation of both cytokinin-like substances. We conclude that the influence of R and cholines on the concentration of substances with cytokinin activities detected in the leaves might be involved in the stimulation of Chl accumulation.     

Antioxidant Enzyme Isoforms on Gels in Two Poplar Clones Differing in Sensitivity After Exposure to Ozone

The effect of acute ozone (O₃) fumigation on isozyme patterns of superoxide dismutase (SOD), peroxidase (POD) and ascorbate peroxidase (APX) in mature (ML) and young leaves (YL) of two poplar clones, contrasting in O₃-sensitivity was analysed. Untreated leaves of both the O₃-sensitive (O₃-S) clone Eridano of Populus deltoides×P. maximowiczii and the O₃-resistant (O₃-R) clone I-214 of P.×euramericana showed four distinct SOD isoforms with a relative mobility (R_f) of 0.54 (MnSOD), 0.60 (Cu/ZnSOD), 0.65 (unidentified), and 0.71 (Cu/ZnSOD). After O₃-fumigation the activity of the SOD isoforms showed only quantitative variations with respect to control plants. In ML of untreated O₃-R plants seven POD isoforms (R_f= 0.13, 0.19, 0.34, 0.59, 0.64, 0.70 and 0.75) were found, while in YL one isoform (R_f= 0.34) was undetected. Only three POD isoforms in both ML and YL of untreated O₃-S plants were resolved. The electrophoretic pattern of POD in O₃-S leaves was greatly modified by acute O₃-fumigation with the appearance of new isoforms in both YL and ML and the disappearance of an isoform (R_f= 0.13) in YL. Additionally, O₃-exposure induced the appearance of two APX isoforms in YL (R_f= 0.66 and 0.70), and one isoform in ML (R_f= 0.70) of the O₃-S clone. By contrast, the activity of the three APX isoformes (R_f= 0.64, 0.70 and 0.76) detected in O₃-R leaves showed only quantitative variation with respect to untreated plants. From these data it is concluded that: 1) in these poplar hybrids antioxidant enzyme activity is developmentally regulated and greatly affected by acute O₃ stress treatments and 2) the different enzymes activity displayed by the two poplar clones, especially for POD and APX isoformes, could partly explain their distinct O₃-sensitivity.     

Alteration of redox state of human serum albumin in patients under anesthesia and invasive surgery

Human serum albumin is a mixture of mercapt- (HMA, reduced form) and nonmercaptalbumin (HNA, oxidized form). We studied the mercapt↔nonmercapt conversion of human serum albumin, which reflects the redox state of the extracellular fluids, in cardiac and other common surgical patients using high-performance liquid chromatography. Mean values of [(HMA)/(HMA + HNA)] ± standard deviation [f_HMA ± σ], for patients who received common surgery (group 1) and cardiac surgery (group 2) at the start of anesthesia were0.636±0.50(n=83) and 0.615±0.062(n=14), respectively. f_HMA values were markedly lower than those for healthy male adults of 0.750±0.028(n=28). f_HMA values increased at 24 h after the start of anesthesia and decreased on the 4th postoperative day in most of the patients. These postoperative changes were prominent in surgical cardiac patients. Although f_HMA values after the 7th postoperative day recovered to those at the start of anesthesia in almost all of common surgical patients, those in cardiac surgical patients, never recovered even on the 21st postoperative day.     

Occurrence of Indoleacetaldehyde and Tryptophol in the Extracts of Etiolated Shoots of Pisum and Helianthus Seedlings

Presence of a non-acidic, growth-promoting indole compound, identical in R_f and colour reaction and closely similar in UV spectrum to synthetic indoleacetaldehyde (IAAId) has been demonstrated in extracts of etiolated shoots of Pisum and Helianthus. On chemical as well as enzymic oxidation of this neutral extract, activity passes over into the acidic fraction. This neutral substance is believed to be IAAId and occurs in the free state as short-term, low temperature extractions indicate. On the basis of R_f, colour reaction and UV spectrum, tryptophol has also been identified in Helianthus extracts. Its identification in pea extracts, however, rests only on R_f, colour reaction and inactivity in Avena bioassays.     

Genetic variation in yield under hot ambient temperatures spotlights a role for cytokinin in protection of developing floral primordia

Unusually hot ambient temperatures (HAT) can cause pre‐anthesis abortion of flowers in many diverse species, limiting crop production. This limitation is becoming more substantial with climate change. Flower primordia of passion fruit (Passiflora edulis Sims) vines exposed to HAT summers, normally abort. Flower abortion can also be triggered by gibberellin application. We screened for, and identified a genotype capable of reaching anthesis during summer as well as controlled HAT conditions, and also more resistant to gibberellin. Leaves of this genotype contained higher levels of endogenous cytokinin. We investigated a possible connection between higher cytokinin levels and response to gibberellin. Indeed, the effects of gibberellin application were partially suppressed in plants pretreated with cytokinin. Can higher cytokinin levels protect flowers from aborting under HAT conditions? In passion fruit, flowers at a specific stage showed more resistance in response to HAT after cytokinin application. We further tested this hypothesis in Arabidopsis. Transgenic lines with high or low cytokinin levels and cytokinin applications to wild‐type plants supported a protective role for cytokinin on developing flowers exposed to HAT. Such findings may have important implications in future breeding programmes as well as field application of growth regulators.     

In vitro antimicrobial activity of zimmu ( Allium sativum L. ‘ Allium cepa L.) leaf extract

The fungitoxic effect of various medicinal plants belonging to different families was evaluated in vitro on Rhizoctonia solani, the rice sheath blight pathogen. Of the various plant extracts, the leaf extract of zimmu (Allium cepa × Allium sativum) showed the maximum antifungal activity against R. solani and recorded an inhibition zone of 12?mm. The leaf extract of zimmu was also effective in inhibiting the growth of other agronomically important fungal and bacterial pathogens viz., Aspergillus flavus, Curvularia lunata, Alternaria solani, Xanthomonas oryzae pv. oryzae, Xanthomonas campestris pv. malvacearum and Xanthomonas axonopodis pv. citri. The antimicrobial compound was dissoluble in methanol and the methanolic extract showed the absorption maxima at 210?nm and 230?nm. Phenolic compounds were present in greater amounts in methanol extract of zimmu. TLC analysis showed the appearance of two blue spots at R _f ?=?0.65 and R _f ?=?0.90. The compounds eluted at R _f ?=?0.65 and R _f ?=?0.90 by preparative TLC exhibited strong antifungal activity against R. solani.     

Respiration acclimation contributes to high carbon-use efficiency in a seasonally dry pine forest

Predictions of warming and drying in the Mediterranean and other regions require quantifying of such effects on ecosystem carbon dynamics and respiration. Long‐term effects can only be obtained from forests in which seasonal drought is a regular feature. We carried out measurements in a semiarid Pinus halepensis (Aleppo pine) forest of aboveground respiration rates of foliage, R_f, and stem, R_t over 3 years. Component respiration combined with ongoing biometric, net CO₂ flux [net ecosystem productivity (NEP)] and soil respiration measurements were scaled to the ecosystem level to estimate gross and net primary productivity (GPP, NPP) and carbon‐use efficiency (CUE=NPP/GPP) using 6 years data. GPP, NPP and NEP were, on average, 880, 350 and 211 g C m^?2 yr^?1, respectively. The above ground respiration made up half of total ecosystem respiration but CUE remained high at 0.4. Large seasonal variations in both R_f and R_t were not consistently correlated with seasonal temperature trends. Seasonal adjustments of respiration were observed in both the normalized rate (R₂₀) and short‐term temperature sensitivity (Q₁₀), resulting in low respiration rates during the hot, dry period. R_f in fully developed needles was highest over winter–spring, and foliage R₂₀ was correlated with photosynthesis over the year. Needle growth occurred over summer, with respiration rates in developing needles higher than the fully developed foliage at most times. R_t showed a distinct seasonal maximum in May irrespective of year, which was not correlated to the winter stem growth, but could be associated with phenological drivers such as carbohydrate re‐mobilization and cambial activity. We show that in a semiarid pine forest photosynthesis and stem growth peak in (wet) winter and leaf growth in (dry) summer, and associated adjustments of component respiration, dominated by those in R₂₀, minimize annual respiratory losses. This is likely a key for maintaining high CUE and ecosystem productivity similar to much wetter sites, and could lead to different predictions of the effect of warming and drying climate on productivity of pine forests than based on short‐term droughts.     

Cytokinins and Morphological Aspects of French-bean Roots in the Presence of Rhizobium

Typical abnormalities were observed on French-bean roots when the plants were cultivated in the presence of Rhizobium phaseoli, under hydroponic conditions. Substantial quantities of cytokinins were detected in the plant culture medium and their concentration remained high until the 9th day after inoculation, when the first nodules appeared. The presence of both partners, plant and bacteria, was required for this synthesis. Exogenous cytokinin production was responsible for morphological alterations of the roots observed before nodulation.     

The role of the vagus nerve in the generation of cardiorespiratory interactions in a neotropical fish,the pacu, <Emphasis Type="Italic">Piaractus mesopotamicus</Emphasis>

The role of the vagus nerve in determining heart rate (f _H) and cardiorespiratory interactions was investigated in a neotropical fish, Piaractus mesopotamicus. During progressive hypoxia f _H initially increased, establishing a 1:1 ratio with ventilation rate (f _R). Subsequently there was a hypoxic bradycardia. Injection of atropine abolished a normoxic inhibitory tonus on the heart and the f _H adjustments during progressive hypoxia, confirming that they are imposed by efferent parasympathetic inputs via the vagus nerve. Efferent activity recorded from the cardiac vagus in lightly anesthetized normoxic fish included occasional bursts of activity related to spontaneous changes in ventilation amplitude, which increased the cardiac interval. Restricting the flow of aerated water irrigating the gills resulted in increased respiratory effort and bursts of respiration-related activity in the cardiac vagus that seemed to cause f _H to couple with f _R. Cell bodies of cardiac vagal pre-ganglionic neurons were located in two distinct groups within the dorsal vagal motor column having an overlapping distribution with respiratory motor-neurons. A small proportion of cardiac vagal pre-ganglionic neurons (2%) was in scattered positions in the ventrolateral medulla. This division of cardiac vagal pre-ganglionic neurons into distinct motor groups may relate to their functional roles in determining cardiorespiratory interactions.     

Optimization of medium composition for the production of antimicrobial activity by Bacillus subtilis B38

An antimicrobial activity produced by Bacillus subtilis B38 was found to be effective against several bacteria, including pathogenic and spoilage microorganisms such as, Listeria monocytogenes, Salmonella enteridis, and clinical isolates of methicillin‐resistant Staphylococcus species. Nutrients such as carbon, nitrogen sources, and inorganic salts enhanced the production level of the antibacterial activity by B. subtilis B38. A first screening step showed that lactose, ammonium succinate, and manganese most influenced both cell growth and antibacterial activity production. These three factors varied at two levels in eight experiments using full factorial design. Results indicated that maximum cell growth (OD = 10.2) and maximum production of antibacterial activity (360 AU/mL) were obtained in a modified medium containing 1.5% (w/v) lactose, 0.15% (w/v) ammonium succinate, and 0.3 mg/L manganese. Depending on the indicator strain used, the antibacterial activity was 2‐ to 4‐fold higher in the modified culture medium than in TSB medium under the same conditions. Thin layer chromatography‐bioautography assay showed the presence of three active spots with R_f values of 0.47, 0.7, and 0.82 in TSB medium. However, the inhibition zone of two spots (R_f values of 0.7 and 0.82) was slightly larger in the modified medium. Moreover, a large zone of inhibition with an R_f value of 0.3, was observed in this modified medium, instead of the spot having an R_f value of 0.47. These results suggest that the nutrients act as environmental factors, quantitatively and qualitatively affecting the production of antibacterial compounds by B. subtilis B38. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009     

The phenoloxidases of the ascomycete Podospora anserina: The three forms of the major laccase activity

In Podospora anserina three laccase activities (I, II and III) were identified. Present results show the existence of an additional lacaase (an anodic protein; MW 80,000; R_f 0.07). Laccase IV derived from the dissociation at acid pH (4.5) of a protein which showed identical molecular weight (390,000) and R_f (0.1) to the oligomeric laccase I. The recovery of laccase I activity when starting from laccase IV (purified by means of isoelectric focusing) suggests that laccase I itself was the source of laccase IV. In turn, laccase IV gave rise to the laccase III after electrophoresis or dialysis at basic pH (8.5).     

Changes in Endogenous Plant Hormones in Cherry Tomato Fruits during Development and Maturation

Hormonal extracts of cherry tomato fruits (Lycopersicon esculentum Mill.) cv. Small Fry at different stages of fruit development and maturation were bioassayed for their auxin, gibberellin, cytokinin and growth inhibitor activities. In general, the levels of endogenous growth promoters were much higher in the young developing fruits than in the more mature fruits. Free cytokinin levels were highest in the first two weeks of development then declined rapidly. However, cytokinin activity in the ribotide fraction, after treatment with alkaline phosphatase, decreased during thefirst three weeks of development then increased rapidly over the following four weeks. Auxin levels increased during early development to reach a maximum in three-week-old fruits after anthesis. Gibberellin levels during the first two weeks of development were much lower than those of auxins and cytokinins, but then increased to reach a peak in the fourth week after anthesis. A growth inhibiting substance with Rf similar to that of abscisic acid was found in the acidic fraction of the fruit extracts. This inhibitor increased gradually during fruit growth and development and reached a peak at the age of five weeks which coincides with the green mature stage.     

Comparison of cytokinin- and auxin-like activity in some commercially used seaweed extracts

Six commercially used seaweed extracts were tested for cytokinin- and auxin-like activity using the soybean callus bioassay and the mung bean rooting bioassay respectively. All the seaweed extracts tested showed cytokinin-like activity. Seamac caused the most callus growth with activity being concentrated at R _f 0.9 which co-chromatographed withiso-pentenyladenine and its riboside. The other five seaweed extracts yielded activity at R _f 0.7–0.8. This co-chromatographed with zeatin and zeatin riboside. All the seaweed extracts tested improved rooting of mung beans. Kelpak made fromEcklonia maxima (Osbeck) Papenf. gave the best rooting response.