Soluble Isoperoxidase Research Articles

Changes in phenol content and peroxidase activity during in vitro organogenesis in Xanthosoma sagittifolium L.

Direct plant regeneration, multiple shoot formation and callogenesis were induced from cocoyam shoot tips cultured in vitro. At different stages of culture, phenol content, peroxidase activity and acidic soluble isoperoxidase patterns were analysed in plantlets. Results showed that phenol content of plantlets cultured on auxin-free media decreased with time, while it increased in those cultured on media supplemented with an auxin. Each form of morphogenesis induced with a growth regulator was preceded by an increase in total peroxidase activity. On hormone-free medium, organogenesis occurred (single shoot development and rhizogenesis), but there was no increase in total peroxidase activity. The appearance of isoperoxidase A2 was associated with root initiation, while the disappearance of isoperoxidase A5 and the appearance of isoperoxidase A6 preceded multiple shoot formation. These results indicate that total peroxidase activity was not a proper marker for organogenesis in cocoyam. Each form of morphogenetic differentiation is associated with an alteration of the acidic isoperoxidase pattern. These enzymes can be used as biochemical markers for rooting and multiple shoot initiation in cocoyam.

Phenol content, acidic peroxidase and IAA-oxidase during somatic embryogenesis in Theobroma cacao L.

Calli were induced in cacao cotyledon explants on a half-strength Murashige and Skoog medium containing 6 × 10-2 g m-3 saccharose and various combinations of 2,4-dichlorophenoxyacetic acid (2,4-D) with kinetin (kin), benzylaminopurine (BAP) or 2-isopentenylphosphate (2-iP). Experiments were carried out on two clones of cacao differing in their susceptibility to black pod disease. The highest percentage of explants forming callus and the most rapid callus development were obtained with 10-6 g m-3 2,4-D and 0.5× 10-6 g m-3 kin. Somatic embryogenesis and rhizogenesis were induced by transferring 3-week-old callus in a half strength Murashige and Skoog medium containing 3 × 10-2 g m-3 saccharose and NAA or IBA in the 0 to 5 × 10-6 g m-3 concentration range. No differentiation could be observed when the medium was supplemented with kin or BAP. The conversion of callus into somatic embryos and roots was accompanied by a drop in phenol content and an increase in peroxidase and IAA-oxidase activities. Moreover, cell differentiation was characterized by the persistence in the callus of one acidic soluble isoperoxidase which was not detected in nondifferentiating callus. Although some differences were noticed between the clones, alterations responsible for cell differentiation were the same in both genotypes.

Soluble peroxidase gradients in lupin hypocotyls and the control of the level of polarly transported indole-3yl-acetic acid

The distribution of basic soluble isoperoxidases along the growth gradient of lupin hypocotyl was studied in order to establish the role of these isoenzymes in controlling polarly transported indole-3yl-acetic acid (IAA) levels. The observation that the levels of basic isoperoxidases, which diminish from the young (vascular differentiating) to the older (vascular differentiated) tissues, are related with previously reported IAA oxidation rates in decapitated plants, suggests that these isoenzymes can play a role in the oxidation of IAA during polar transport. The fact that the level of basic isoperoxidases is controlled by IAA in hypocotyl sections harvested from different growth zones is in accordance with the previously described adaptative activation of basic isoperoxidases to IAA content. This adaptative activation of basic isoperoxidases might constitute the basic characteristic of a system of subcellular oscillators, coupled at the cellular level, necessary to generate the supracellular auxinwave associated with auxin transport.

Subcellular location of basic and acidic soluble isoperoxidases in Lupinus

The subcellular location of non-particulate (soluble) peroxidases (EC 1.11.1.7) was studied in lignifying lupin ( Lupinus albus L.) hypocotyls. Supernatants of cellular homogenates contain two acidic (A 1 and A 2) and two basic (B 1 and B 2) isoperoxidases. Studies of centrifugation on isopycnic sucrose gradients of cellular homogenates of plasmolyzed tissues, vacuum infiltration of hypocotyl sections, and binding probes to membranes and cell walls, suggest that while basic soluble isoperoxidases possess a cytoplasmic location, acidic isoperoxidases possess an extracellular location, as freely soluble forms in the intercellular spaces. These results are discussed on the basis of the subcellular location of the auxin catabolism, mediated mainly by the two basic isoperoxidases, which in lupin cells at least, seems to be restricted to the cytosolic compartment.

Biochemical changes in primary wheat leaves during growth and senescence

Changes in the different forms of the total activity of peroxidases (soluble, ionically and covalently bound), in the soluble isoperoxidase composition, and in the content of protein and chlorophyll during growth and senescence of the intact primary leaves of spring wheat were studied. The forms of peroxidases are in inverse relationship to the growth and increase during development and senescence, especially towards the end of senescence. The activity of peroxidases does not follow the physiological age of wheat leaves during the whole period of vegetation unlike the contents of protein and chlorophyll. The intensity of anodic and cathodic peroxidase isoenzyme bands 1 and 5 increases during senescence, but anodic bands number 2 and 4, cathodic bands 2 and 3 decrease. Changes in the activity of peroxidases and in the content of protein and chlorophyll as indicators of senescence are discussed.

Soluble, Membrane and Wall Peroxidases, Phenylalanine Ammonia-lyase, and Lignin Changes in Relation to Vitrification of Carnation Tissues Cultured in vitro

Vitrification of carnation tissues by passage from solid to liquid medium was accompanied by decreased lignin content. The higher lignin level of normal tissues corresponded to a higher phenylalanine ammonia-lyase activity. It also paralleled a much higher activity of soluble and wall peroxidases towards syringaldazine. Kinetical analysis of soluble isoperoxidases indicated a two-step control of basic and acidic enzymes with a diminished activity of the latter in glassy plants. Compartment analysis of guaiacol peroxidases showed a different distribution in malformed tissues.

Seasonal Changes In C6-C3 Acids And The Activity Of Different Forms Of Peroxidases During The Vegetative Growth Of Shoots Of The Apple-Tree (Malus Domestica Borkh.)

Summary The Article Reports About Seasonal Changes In The Content Of Hydroxycinnamic Acids In Xylem, A Study Of The Different Forms Of The Total Activity Of Peroxidases (Soluble, Ionically And Covalently Bound) In Xylem And Cambium And Of The Soluble Isoperoxidase Composition In Cambium And As Well As In Xylem Of The One-Year-Old Vegetative Shoots Of The Apple-Tree In Connection With The Differentiation Of Cells And The Lignification Of Cell Walls. Phenolic Cinnamic Acids Are Present In Xylem As Free Acids And By Alkaline Hydrolysis In Ethanol Extract (“Soluble Esters”) And In The Insoluble Residue (“Insoluble Esters”). Experiments Indicate That Insoluble Esters May Be Involved More Intensively Than Free And Soluble Esters In Lignin Biosynthesis During The Differentiation Of Cells. The Degree Of The Total Activity Of All Different Forms Of Peroxidases Rises With The Differentiation Of Cells And Of Tissues, Reaching Their Maxima In Cambial Cells In August And In Xylem Cells In September, And Thereafter Their Activity Begins To Decrease. Covalently Bound Peroxidase In Cell Walls Indicates The Highest Degree Of Activity Of The Special Froms Of Peroxidases And May Be One Of The Indicators In The Process Of Lignification. Measurement Of The Activities Of The Isoenzyme Patterns Of Soluble Peroxidase Reveals That Changes Are Different In Cambium And Xylem. Changes In The Content Of Cinnamic Acids As Well As Changes In The Activity Of Peroxidases In The Vegetative Growth Of Shoots Of The Appletree Can Be Regarded As Biochemical Markers Of Differentiation And Lignification.

Isoperoxidases in Epidermal Layers of Tobacco and Changes during Organ Formation in vitro

AbstractThe content and pattern of soluble isoperoxidases were determined in epidermal explants taken from different internodes of tobacco plants in the vegetative and floral states. There were qualitative and quantitative differences in the isoperoxidases, with a decrease in content and fewer bands being observed acropetally, i.e., in going from the base of the stem towards the apex. Epidermal explants from floral branches were grown in in vitro culture, with various media moditications, to form de novo floral or vegetative buds, roots or callus. Changes in soluble isoperoxidases were followed electrophoretically in relation to these varying morphogenetic pathways. In each of them, the number of bands increased on both the anodic and cathodic sides with time in culture. Compared to each other these four morphogenetic programmes were different in their peroxidase zymograms, mainly through varying kinetics in the development of activity of the isoenzymes. The changes observed during root and vegetative bud formation agree with previously published data, and the changes during floral bud formation agree with those observed in vivo.