Artichoke Tissue Research Articles

Impact of Rhizobacterial Inoculants and Organic Amendment on Bacterial Communities of Jerusalem artichoke Tissue and Rhizosphere by using Denaturing Gradient Gel Electrophoresis

The application of organic amendments can improve soil quality and influence bacterial communities, contributing to enhanced soil health in agricultural systems. This study investigated the effect of using rain tree leaf, corn husk, and peat moss as soil amendments, supplemented with plant growth promoting rhizobacteria on communities of bacteria in the tissue and rhizosphere of Jerusalem artichoke. The plants were observed for 120 days after transplanting. Polymerase chain reaction-denaturing gradient gel electrophoresis (DGGE) technique was used to investigate the impact of both organic amendments and bacterial consortium with comparative profiles. Comparison DGGE profile by clustering analysis did not clearly separate each organic amendment and bacterial inoculation, but principal component analysis (PCA) revealed that plant age had an influence on tissue and rhizosphere bacterial communities. The results indicated that soil amendments and bacterial inoculation had no effect on bacterial community shifts. Interestingly, the genera of bacteria able to most colonize in the tissue and rhizosphere were the uncultured bacteria. Thus, we provide promising data for boosting Jerusalem artichoke growth and soil quality with potential organic amendments to improve soil with sustainable strategies.

An RNA World.

My research career started with an ambition to work out how genes are regulated in plants. I tried out various experimental systems-artichoke tissue culture in Edinburgh; soybean root nodules in Montreal; soybean hypocotyls in Athens, Georgia; and cereal aleurones in Cambridge-but eventually I discovered plant viruses. Viral satellite RNAs were my first interest, but I then explored transgenic and natural disease resistance and was led by curiosity into topics beyond virology, including RNA silencing, epigenetics, and more recently, genome evolution. On the way, I have learned about approaches to research, finding tractable systems, and taking academic research into the real world. I have always tried to consider the broader significance of our work, and my current projects address the definition of epigenetics, the arms race concept of disease resistance, and Darwin's abominable mystery.

Callus inductions and Phytochemical Determination of Artichoke (Cynara scolymus) growing in Iraq

The artichoke (Cynara scolymus) belongs to Asteraceae family. It is included in British and European Pharmacopeia and has long–used in traditional medicine in several countries. The plant primarily grows in North Africa and Mediterranean; in addition, it is cultivated around the world. Artichoke is wildly distributed in Iraq at the watery lines and boundary of the field. The aim of study was to induce callus from leaves as explants, and to compare between contents of total phenolic and total flavonoids that extracted from the induced callus and from leaves. The induced callus was maintained on Murashige and Skoog (MS) medium supplemented with Naphthalene Acetic Acid (NAA) and Benzyl Adenine (BA). The highest percentage of callus (100%) was induced from the combination (5mg/l NAA plus 2 mg/l BA), followed by (86.67%) with the combination (3mg/l NAA plus 1mg/l BA). Two types of callus (friable and compact) were induced. The extract of friable callus produced 0.858 mg/g of total phenolic, while leaves extract produced 167.24 µg/ mg of total flavonoids. Auxins and cytokinins that added together in the culture medium seemed to be necessary for artichoke tissue culture.

Designing a modified atmosphere packaging (MAP) for fresh-cut artichokes

‘Catanese’ artichoke quarters were packaged in active modified atmosphere (5% O2+10% CO2) in four different materials or in air in macro-perforated bags used as control (CTRL), and stored at 4°C. Materials used for modified atmosphere packaging (MAP) were: polylactic acid (PLA), polylactid acid with one line of micro-perforation (PLA MF1), polypropilene with two lines of micro-perforations (PP MF2), and polypropylene + polyamide with two lines of microperforations (PP+PA MF2). Initially and after 2, 4, and 9 days, overall artichoke appearance, color and weight loss were monitored. O2 and CO2 concentrations within the packages were detected initially and after 1, 2, 17, 24.5, 41.5, 49.5, 120 and 216 h (end of the experiment). Also, at the last sampling date ethanol and acetaldehyde accumulations in artichoke tissue were measured. All the micro-perforated films maintained gas levels within the range of O2>3% and CO2<15%, defined as “safe”, with a positive effect on quality: all samples remained above the limit of marketability until the end of the experiment, without significant differences among them, but showed a slight better overall appearance and, accordingly, a better retention of color parameters when compared with CTRL samples. Complete anaerobic condition (16% CO2 and 0% O2) developed in PLA bags where blackening of cut bracts and receptacle was observed, while black spots appeared on outer bracts, causing drastic quality reduction; samples fell below the limit of marketability after just 2 days. Also a significant accumulation of ethanol and acetaldehyde was found in these samples. Optimizing MAP made it possible to maintain the desired gas condition, with positive effects on quality of the produce in absence of any stabilizing treatment, for 9 days.

A Novel Amperometric Biosensor Based on Artichoke (Cynara scolymus L.) Tissue Homogenate Immobilized in Gelatin for Hydrogen Peroxide Detection

A biosensor for specific determination of hydrogen peroxide was developed by using homogenized artichoke (Cynara scolymus L.) tissue in combination with a dissolved oxygen probe and applied in determination of hydrogen peroxide in milk samples. Artichoke tissue, which has catalase activity, was immobilized with gelatine by means of glutaraldehyde and fixed on a pretreated teflon membrane. The electrode response was maximum when 0.05 M phosphate buffer was used at pH 7.0 and at 30 degrees C. Upon addition of hydrogen peroxide, the electrode gives a linear response in a concentration range of 5.0-50 x 10(-5) M with a response time of 3 min. The method was also applied to the determination of hydrogen peroxide in milk samples.

Regulation of Ribosomal RNA Accumulation by Auxin in Artichoke Tissue

Artichoke (Helianthus tuberosus L.) tuber tissue cultured in the presence of the auxin 2,4-dichlorophenoxyacetic acid accumulates ribosomal RNA at a rate of 0.135 micrograms per hour per explant whereas there is little accumulation in nontreated tissue. The addition of auxin enhanced the transcription of the 2.5 x 10(6) precursor 3.5-fold and increased the rate of processing 1.8-fold. The major effect of auxin, however, was a vast increase in the rate of processing of the 1.39 x 10(6) precursor to the 1.3 x 10(6) mature ribosomal RNA. The incorporation of label into the 0.7 x 10(6) mature ribosomal RNA of treated tissue was in 10-fold excess over the control after a 30-minute pulse and remained so throughout the remainder of the labeling period. This level, however, was not reached for the complementary 1.3 mature RNA until 3 hours of continuous labeling, decreasing from a initial value of 40-fold excess. A complication in the processing of ribosomal RNA is the apparent increase in the stability of the 0.7 x 10(6) mature RNA with auxin treatment.

DNA and histone content of immature tracheary elements from cultured artichoke explants

Relative amounts of DNA and histone were determined by Feulgen microdensitometry and alkaline fast-green microdensitometry in differentiating tracheary elements in cultured explants of Jerusalem artichoke (Helianthus tuberosus L.) tubers. The absence of endopolyploidy in cultured artichoke tissue was confirmed, and the nuclei of tracheary elements were exclusively at the 2C level for both DNA and histones.

The Use of 6-MP to Investigate the Control of Glucose-6-Phosphate Dehydrogenase Levels in Cultured Artichoke Tissue

The Use of 6-MP to Investigate the Control of Glucose-6-Phosphate Dehydrogenase Levels in Cultured Artichoke Tissue

The effect of inhibitors of protein and nucleic acid synthesis on nucleolar size and enzyme induction in Jerusalem artichoke tuber slices

The effects of various inhibitors of protein and nucleic acid synthesis on the development of invertase activity and increased nucleolar volume in discs excised from tubers of artichoke tissue are compared. The results are discussed with reference to the current theories relevant to the action of the inhibitors and to the nature of the increase in nucleolar volume.

Inhibition by actinomycin D of water uptake and invertase and hydrolase activities induced in Jerusalem artichoke tuber tissue disks by treatment with 2,4-dichlorophenoxyacetic acid

Actinomycin D was found to inhibit the water uptake and both the invertase and hydrolase activities induced by treatment of Jerusalem artichoke tissue disks with 10 −5M solutions of 2,4-dichlorophenoxyacetic acid. None of the treatments were found to produce any measurable change in the amounts of total soluble protein or invertase or hydrolase activity. These results provide further evidence that increases in the activities of both invertase and hydrolase induced by 2,4 D are dependent upon the continued synthesis of a messenger RNA.

Effects of Kinetin on Respiration Ethylene Production and Ripening of Banana Fruit Slices

Thin slices cut from many plant tissues develop an increased respiration rate in the day or days after cutting (Laties 1963; ap Rees 1966). Mter slicing, the metabolism of the tissue changes in a number of respects including the capacity for salt and other solute uptake (Asprey 1937; MacDonald 1967), the relative contri-bution of the pentose phosphate shunt to total hexose catabolism !ap Rees and Beevers 1960; ap Rees 1966), and the induction of a number of enzymes (Edelman and Hall 1965; Willemot and Stumpf 1967). In the case of slices of arti-choke tissue, the presence of either indoleacetic acid or kinetin inhibits the increases, in response to slicing, of respiration, of phosphate uptake, and of invertase activity (Palmer 1966). While aspects of the latter experiments have been criticized (Vaughan and MacDonald 1967) the conclusion that the growth factors affect the response to slicing has not been challenged.

The induction of phosphatase activity in thin slices of Jerusalem artichoke tissue by treatment with indole acetic acid

Prolonged washing of thin slices of Jerusalem artichoke (Helianthus tuberosus) did not result in any apparent increase in the activity of the phosphatase enzymes, although the washing process is known to stimulate the activity of many other enzymes. However, treatment of the tissue in either 3×10(-5)M 2,4-dichlorophenoxyacetic acid or 10(-4)M indole acetic acid resulted in a 3-fold increase in the phosphatase activity. Significant stimulations of activity were detectable one hour after placing the tissue in the auxin. Treatment of the tissue in either kinetin or gibberellic acid failed to stimulate the activity of the enzyme. The enhancement of phosphatase activity caused by auxins could not be prevented by adding cycloheximide to the treatment solution an it is concluded that the stimulation occurred as the result of the activation of enzyme already present in the tissue rather than by the de novo synthesis of new enzyme protein.

Quantitative microspectrophotometry of RNA in plant tissue

Chemical estimation of nucleic acid, essentially RNA, in fixed tissue from Jerusalem artichoke tubers, coupled with an examination of the types of RNA in the fixed tissue by gel electrophoresis, demonstrates that ribosomal and ‘soluble’ RNA are preserved in this tissue after various fixation procedures including methanol, ethanol-acetic acid and aqueous formaldehyde. Tissue fixed in ethanol-acetic acid or formaldehyde is resistant to loss of nucleic acid by aqueous extraction but tissue fixed in all three standard fixatives loses nucleic acid in citrate buffer under conditions used for Azure B staining. The presence of Azure B in the buffer does not wholly prevent this loss. Tissue fixed in formaldehyde or mixed fixatives containing formaldehyde is resistant to loss of nucleic acid during treatment with EDTA to obtain cell suspensions. Preliminary experiments with Azure B, Gallocyanin chrome-alum and Methylene Blue showed that the Gallocyanin technique is the most practicable for demonstrating RNA cytochemically. Its specificity was confirmed by ribonuclease extraction of the tissue. Optimum staining conditions, requiring treatment of the tissue in Gallocyanin chrome-alum solution overnight at 40°C, are established for the artichoke tissue and for paraffin sections of pea shoot apices.

EFFECT OF INDOLYL-3-ACETIC ACID ON THE PERMEABILITY OF MEMBRANES IN STORAGE TISSUE.

A STRIKING difference between the response of coleoptile tissue and storage tissue to applied auxin is that the former is immediate and the latter exhibits a lag period1–3. Sperling and Laties4 have recently shown that in potato or Jerusalem artichoke tissue slices auxin response depends on the progress of metabolic changes associated with the lag period (ageing of tissue), and auxin had to be applied to fresh tissue to be effective. A similar characteristic feature of freshly cut storage tissue is that it requires the completion of a lag period before salt is accumulated. At least in the case of potassium this phenomenon was shown to be due to a reduction in the permeability of the outer cell membrane5.

Ribonucleic Acid and Protein Synthesis as Essential Processes for Cell Elongation

Reports of changes in RNA and protein metabolism associated with cell expansion are numerous. Results often depend on whether studies on cell expansion were done with intact plants or with excised parts. A net increase in protein content is usually associated with intact cell extension (6, 15, 17, 30), while excised tissues usually show a net decrease (9, 18, 30, 33). A possible exception to the latter phenomenon was reported by Thimann and Loos (32) for excised potato and artichoke tissue. In these tissues, auxin stimulated the synthesis of protein over a 4-day period. Burroughs and Bonner (8) demonstrated protein synthesis associated with only slight variation in protein content during growth of excised coleoptile tissue. However, auxin did not affect the amount of C14-amino acid incorporated into protein of the coleoptile tissue during 6 hours. Changes in specific activities and amounts of certain enzymes occur in association with cell elongation (3, 7, 14, 27, 28). Studies on changes in RNA metabolism associated with cell expansion are equally complex. There is usually a progressive increase in RNA content per cell from the apical meristem through the zone of radial enlargement (15,17), but in corn mesocotyl tissue (19), there was a net decrease in RNA per cell associated with cell expansion and maturation. The association of RNA with various cell organelles, as measured by differential centrifugation, changes in certain tissues during cell expansion and maturation (10, 19, 23, 29). In excised tissues, a net decrease in RNA is usually associated with cell expansion (10, 20, 33, 35). With corn mesocotyl, growth-promoting concentrations of auxin enhanced the rate of RNA breakdown (20, 33), but this was not observed in soybean hypocotyl tissue (18, 21). In the expanding zone of excised soybean hypocotyl, auxin enhanced C14-nucleotide incorporation into RNA (21), but this did not occur with corn mesocotyl (20). The differences in RNA metabolism in elongating zones of soybean hypocotyl and corn mesocotyl may be attributable to differences in the degradative metabolism of RNA in these tissues. Corn mesocotyl has been shown to have more ribonuclease activity than soybean hypocotyl (34), and low concentrations of auxin enhance ribonuclease activity in corn mesocotyl during excised growth (30). There is little or no change in ribonuclease activity of soybean hypocotyl during excised growth with or without auxin. The growth rate of corn root tips correlates positively with the RNA content of the tissue (35). Woodstock and Skoog (36) hypothesized that the amount of RNA synthesis by the cells of the root apex determines their subsequent rate of elongation. They also showed that IAA inhibited growth and RNA synthesis in the corn root. Many lines of evidence support the view that RNA and protein synthesis may function during cell expansion, although no definitive experiments lhave been done. Developments in the field of protein and nucleic acid biochemistry provide a background of information on specific inhibitors which facilitate the study of RNA and protein syntheses. First, the antibiotic actinomycin D inhibits DNA-dependent synthesis of RNA by RNA polymerase at low concentrations (16) and leads to an inhibition of protein synthesis (13, 22). DNA synthesis is inhibited only at higher concentrations (16). Secondly, puromycin is an effective inhibitor of protein synthesis (1, 26). Presumably by formation of abnormal messenger RNA, 8-azaguanine inhibits protein synthesis in bacteria while only slightly affecting RNA synthesis (9). Also, the demonstration that part or all messenger or informational RNA is unstable (rapid turnover) in many systems (22, 25) would implicate continued RNA synthesis for the normal complete development of a cell. Using the elongating zone of the soybean hypocotyl and actinomycin D, puromycin, and 8-azaguanine as specific inhibitors, the essentiality of RNA and protein synthesis for cell elongation was investigated. The data show that RNA and protein synthesis are essential for cell elongation in soybean hypocotyl tissue. There also is suggestive evidence that the role of auxin in regulating cell elongation may be associated with the control of RNA and/or protein synthesis.

The Effect of Auxin on Growth and Respiration of Artichoke Tissue

The Effect of Auxin on Growth and Respiration of Artichoke Tissue

The Absorption and Accumulation of Solutes By Living Plant Cells

ABSTRACT Discs cut from plant storage organs have long been favourite material for experiments upon salt absorption. A recent series of papers (Steward, 1932 a–c, 1933 ; Steward, Wright and Berry, 1932) which refers especially to potato tissue indicates that in the past the attention directed to the respiration of these tissues was far too scanty. With the development of an adequate technique (Steward, 1932 b) the general principles operating in the case of potato tissue became increasingly apparent, and the occasion thus arose to extend the investigations to other storage organs. A survey of several storage organs (Berry and Steward, 1934) revealed that discs cut from artichoke tubers combined a conspicuous ability to absorb the salt studied (KBr) with a characteristic respiratory behaviour which presented features somewhat different from those of potato. The present paper records an attempt to ascertain whether the observed behaviour in respiration is reflected in salt absorption in the manner anticipated and to determine further details of the absorption process, with particular reference to potassium bromide and artichoke tissue. A matter which received some special attention was to ascertain whether the absorbed salt replaces ions already within the cell, or accumulates, against a concentration gradient, in the vacuole where it exists in true solution without displacing other ions. Since they were obtained, the results here presented have gained added interest in the light of the results published by Briggs and Petrie (1931) and, more particularly, in view of a theoretical interpretation of absorption by cells (Briggs, 1932) based upon ionic exchange.