Modern methods of plant analysis
01 Jan 1964-
About: The article was published on 1964-01-01 and is currently open access. It has received 1991 citations till now.
Citations
More filters
TL;DR: In this paper, the spectral properties of lodgepole pine trees under mountain pine beetle attack were investigated and three spectral bands (the green peak, red edge and near-infrared (NIR) shoulder regions) were identified as most promising for detecting early effects of bark beetle attack.
Abstract: Abstract. This paper reports the results of a study of the foliar reflectance properties of lodgepole pine trees under mountain pine beetle attack which aimed to determine the sequence of changes which occur. The motivation for this study was to identify spectral regions showing the earliest signs of attack in order to choose spectral bands for airborne linear array sensors. Normal illumination, diffuse hemispherical reflectance spectra were obtained of needles from trees showing varying degrees of stress from beetle attack and for needles from unattacked trees for comparison. The more pronounced changes in the spectra were interpreted visually and compared to changes reported by other authors. The more subtle changes were studied by analysing variance methods. Three spectral bands (the green peak, red edge and near-infrared (NIR) shoulder regions) have been identified as most promising for detecting early effects of bark beetle attack. Three additional bands (the blue, red and NIR plateau region...
102 citations
01 Jan 2002
TL;DR: Examples of the two most commonly applied techniques in the identification of secondary metabolites in lichenized ascomycetes are presented, including high performance thin-layer chromatography (HPTLC) and high performance liquid Chromatography (HPLC).
Abstract: The identification of secondary metabolites in lichens is a necessity for the correct determination of lichens in numerous groups, and the presence of substances is often mentioned in taxonomic keys. Numerous review papers have discussed the significance of secondary metabolites in lichen taxonomy (e.g., W Culberson 1969, 1970, 1986; WL Culberson and Culberson 1970; Hawksworth 1976; Brodo 1978, 1986; Leuckert 1985; CF Culberson 1986; Egan 1986; Rogers 1989; Lumbsch 1998a, b) and the chemistry of these substances (e.g., Asahina and Shibata 1954; Shibata 1963; Huneck 1968, 1971, 1973, 1984, 1991; Elix et al. 1984). Our knowledge of the biosynthesis of secondary metabolites in lichenized fungi has been summarised by (1969). The biological role of lichen substances was reviewed by (1986), and additional information regarding the ability of aromatic lichen substances to protect against irradiation can be found in (1995). Lichens may utilise secondary metabolites as chelating agents (Purvis et al. 1987), as inhibitors of lichenicolous fungi (Lawrey 1995), and to avoid saturation of the medulla by water (Armaleo 1993). Lists recording the distribution of secondary metabolites in different taxa have been compiled by Chicita Culberson and co-workers (CF Culberson 1969, 1970; CF Culberson et al. 1977). Some methods used in the identification of secondary metabolites in lichenized ascomycetes can be found in the literature cited below, but this chapter is restricted to examples of the two most commonly applied techniques, namely thin-layer chromatography (TLC), including high performance thin-layer chromatography (HPTLC) and high performance liquid chromatography (HPLC). Several publications deal with the identification of lichen substances, the most comprehensive being the recent book by Huneck and (1996). The reader is referred to this and the other publications for more detailed information and additional techniques used in lichen chemistry (Santesson 1973; Leuckert 1984; White and James 1985; CF Culberson and Elix 1989). Table 1 presents a list of the classes of secondary metabolites found in lichen-forming fungi.
101 citations
TL;DR: In this paper, small deformation dynamic rheometry was used to characterise the calcium-induced gelation of low-methoxyl pectins, at two different pH values.
101 citations
TL;DR: Three pigment lines of the tomato cultivar 'Pearson' with isogenic backgrounds were studied to determine the relationship between certain carotenoids and the development of chromoplasts during fruit ripening and the ultrastructural changes in plastids of the two mutant lines.
Abstract: A B S T R A C T Three pigment lines of the tomato cultivar 'Pearson' with isogenic backgrounds were studied to determine the relationship between certain carotenoids and the development of chromoplasts during fruit ripening. The lines were normal red (r+/r+), in which about 90% of the carotenoids in the ripe fruit is lycopene; high-beta (B/B) mutant, in which beta-carotene is the major pigment and the mature fruit color is deep orange; and low-pigment (r/r) mutant, in which carotenoids are drastically reduced and the mature fruit is pale yellow-orange. This paper reports pigment analyses for the three lines and the ultrastructural changes in plastids of the two mutant lines. Very young, pale green fruits contain proplastids with limited lamellar structure. As the fruits reach the mature green stage, the plastids in all three lines develop into typical chloroplasts. Differences in pigment content and in ultrastructure among the lines are not apparent until ripening commences. In the low-pigment mutant carotenoids are reduced as ripening progresses and no carotenoid crystalloids are formed. As chlorophyll decreases the fruits become pale yellow. The grana become disorganized and the thylakoids appear to separate at the partitions and tend to be arrayed in lines, some still with their ends overlapping. Globules increase slightly in number. In the high-beta mutant the grana break down during ripening and globules increase greatly in size and number. Beta-carotene, presumed to be largely in the globules, crystallizes into elongated or druse type forms which may distort the globules. The crystals may affect the shape of the chromoplasts; long crystals may extend the length of the plastid to over 15 Y. Thylakoid plexes with a regular lattice structure sometimes occur in the chromoplasts of the high-beta mutant. Granules resembling aggregations of phytoferritin particles occur in the chromoplasts of both of these mutants.
101 citations
01 Jan 1976
TL;DR: In this paper, the authors stress some of the points which Wood considered as additional evidence required before resistance can reasonably be attributed to a particular substance, and stress the importance of these points.
Abstract: Plant resistance to pathogens based on preformed inhibitory substances is easy to conceive, but despite extensive studies, reviewed by Walker and Stahmann (1955), Allen (1959), Farkas and Kiraly (1962), Tomiyama (1963), Rohringer and Samborski (1967) and Wood (1967) there are only a few well-documented examples. Preformed resistance is often based on inadequate evidence; mainly the demonstration that a crude extract of a plant resistant to a pathogen contains material which reduces the growth of the pathogen in vitro. Therefore, we would like to stress some of the points which Wood (1967) considers as additional evidence required before resistance can reasonably be attributed to a particular substance.
101 citations
References
More filters
01 Jan 1963
TL;DR: In this article, a physiologischer Vorgang auf eine enzymatische Wirkung zuruckgefuhrt werden (vgl. S. 301), besteht die folgende Aufgabe darin, Naheres uber die Eigenschaften des beteiligten Enzyms zu ermitteln.
Abstract: Kann ein physiologischer Vorgang auf eine enzymatische Wirkung zuruckgefuhrt werden (vgl. S. 301), so besteht die folgende Aufgabe darin, Naheres uber die Eigenschaften des beteiligten Enzyms zu ermitteln. Hierzu gehoren die Bestimmung der Reaktions- und Substratspezifitat sowie die Ermittlung der Bedingungen, unter denen eine optimale Wirkung des Enzyms gegeben ist. Wesentlich zur Charakterisierung ist ferner die Untersuchung der Stabilitat des Enzyms und dabei insbesondere die Feststellung, ob es sich um ein Ferment handelt, das zur vollen Aktivitat dialysable Cofaktoren benotigt. Falls diese Frage bejaht wird, ist auch die Bestimmung der unerlaslichen Cofaktoren anzuschliesen. Uberdies bietet auch der Nachweis der Lokalisation des Enzyms in der Zelle (oder im Zellverband) eine entscheidende Moglichkeit zur Charakterisierung des Fermentes. Hinzu kommt schlieslich noch die Untersuchung der Wirkung einzelner Inhibitoren1 auf das Enzym, die zu weitgehender Klarung des Reaktionsmechanismus beitragen kann und eine Abgrenzung der Eigenschaften des untersuchten Fermentes gegenuber ahnlichen Enzymen erlaubt.
2 citations
01 Jan 1962
TL;DR: Optical rotation has been found to be one of the most convenient methods of following the denaturation of proteins and rotatory dispersion is capable of providing information on the folding of the polypeptide chain in proteins and the changes accompanying denaturation.
Abstract: Optical rotation has been found to be one of the most convenient methods of following the denaturation of proteins. Generally speaking denaturation can be defined as a process or sequence of processes in which the spatial arrangement of the polypeptide chains within the molecule is changed from that typical of the native protein to a more disordered arrangement (Kauzmann 1959). The terms “configuration”, “conformation” and “state of folding” are widely used for spatial arrangement. It is probably best to follow the suggestion of Blout (1960) and restrict the use of “configuration” to its original sense, i.e. the spatial arrangement around an asymmetric carbon atom, and to use “conformation” for the shape of the molecule in its entirety. The properties discussed in the previous Chapter i.e., viscosity, diffusion, sedimentation, and light scattering — can all furnish information on the overall shape of proteins or other macromolecules and changes in this shape with environment. Thus Doty, Bradbury and Holtzer (1956) were able to show using these methods, together with streaming birefringence, that poly-γ-benzyl-L-glutamate could exist in two conformations, the α-helix and the solvated randomly coiled form, depending on the solvent. The change from α-helix to random coil was accompanied by marked changes in the optical rotatory properties of the polypeptides. It is to be expected that an α-helical structure should contribute to the rotatory power of a polypeptide since helices are asymmetric and not superimposable on their mirror images. The work on polypeptides has shown that rotatory dispersion is capable of providing information on the folding of the polypeptide chain in proteins and the changes accompanying denaturation.
1 citations