Water Pathways in Wheat Leaves. II. Water-Conducting Capacities and Vessel Diameters of Different Vein Types, and the Behaviour of the Integrated Vein Network

1985 ◽  
Vol 12 (2) ◽  
pp. 183 ◽  
Author(s):  
DP Altus ◽  
MJ Canny ◽  
DR Blackmann
Keyword(s):  
Theoretical Analysis ◽  
Leaf Blade ◽  
Integrated System ◽  
Equivalent Diameter ◽  
Mesophyll Cells ◽  
Wheat Leaf ◽  
Wheat Leaves ◽  
Physical Spaces ◽  
Cross Connect ◽  
Large Vessels

The water-conducting capacity of the lateral veins of the wheat leaf, measured by the velocity of movement of a dye marker, decreases with distance along the leaf towards the tip. The laterals contain a number of small (up to 10 �m) diameter vessels as well as two or three relatively large (up to 45 �m) diameter vessels. The largest vessel in each decreases in diameter with distance along the leaf towards the tip, resulting in the decreased velocity of conduction. The large vessels represent physical spaces through which laminar flow can occur; however, the flow rate is slower than that predicted by the Hagen-Poiseuille law for pipes of equivalent diameter. The intermediate veins contain only several 7-10 �m diameter vessels, and the diameter of the largest vessel in these veins does not change along the length of the leaf. The number of 7-10 �m diameter vessels per vein also remains unchanged. The water- conducting capacity of an intermediate vein is therefore constant along the length of the leaf. The transverse veins that cross-connect neighbouring longitudinal veins all have similar water-conducting capacity regardless of location in the leaf. These measurements support the view that the lateral veins serve to supply water from the base of the leaf to the tip, while the intermediate and transverse veins form a distribution network carrying the water across the leaf to the mesophyll cells. A theoretical analysis is made of the behaviour of the network as an integrated system. Assumed transpiration rates are imposed on the model to find what the pressure gradient along the leaf blade is, what pressures would be produced at the nodes of the network, and what fluxes would result through the vein elements of it. The model predicts movements of water in the intermediate veins very similar to those observed in a previous paper and suggests that the network responds to changes in supply or demand by producing minima of similar pressure in the distributing veins at different distances from the supplying longitudinal veins.

scholarly journals Association of Pestalotiopsis Guepinii (DESM.) Stay. with Bipolaris Leaf Blight (BpLB) Infected Wheat Leaves-A new Record

2016 ◽  
Vol 40 (1) ◽  
pp. 87-90
Author(s):  
Shamim Shamsi ◽  
Mst Selina Momtaz
Keyword(s):  
New Record ◽  
Leaf Blight ◽  
Wheat Varieties ◽  
Anamorphic Fungus ◽  
Wheat Leaf ◽  
Wheat Leaves ◽  
Academy Of Sciences

Pestalotiopsis guepinii (Desm.) Stay an anamorphic fungus belonging to the class Celomycetes was isolated from Bipolaris leaf blight (BpLB) infected wheat leaf of two wheat varieties namely, Balaka and Saurab during the period of February to March, 2011. Association of Pestalotiopsis guepinii with wheat is a new record.Journal of Bangladesh Academy of Sciences, Vol. 40, No. 1, 87-90, 2016

Increased Lipoxygenase Activity is Involved in the Hypersensitive Response of Wheat Leaf Cells Infected with A virulent Rust Fungi or Treated with Fungal Elicitor

1986 ◽  
Vol 41 (5-6) ◽  
pp. 559-563 ◽  
Author(s):  
Carlos A. Ocampo ◽  
Bruno Moerschbacher ◽  
Hans J. Grambow
Keyword(s):  
Hypersensitive Response ◽  
Hypersensitive Reaction ◽  
Rust Fungi ◽  
Lipoxygenase Activity ◽  
Puccinia Graminis ◽  
Compatible Interaction ◽  
Wheat Leaf ◽  
Wheat Leaves ◽  
Germ Tubes ◽  
Wheat Rust

The hypersensitive reaction in incompatible wheat-rust interactions is characterized by an increase in lipoxygenase activity detectable as early as 28 h after penetration of the pathogen. In contrast, lipoxygenase activity in the compatible interaction did not increase until the onset of sporulation.Lipoxygenase activity also increased following treatment of wheat leaves with an elicitor fraction from germ tubes of Puccinia graminis tritici.

Comparative leaf blade anatomy and micromorphology in the systematics and phylogeny of Bambusoideae (Poaceae: Poales)

2019 ◽  
Author(s):  
Thales D Leandro ◽  
Vera L Scatena ◽  
Lynn G Clark
Keyword(s):  
Cross Section ◽  
Leaf Blade ◽  
Research Priorities ◽  
General Description ◽  
Mesophyll Cells ◽  
Surface View ◽  
Stomatal Apparatus ◽  
Phylogenetic Framework

Abstract Leaf blade anatomical and micromorphological data have increasingly proved to be useful in the systematics and phylogeny of Bambusoideae. The presence of well-developed, asymmetrically strongly infolded mesophyll cells (arm cells) as seen in cross-section is regarded a synapomorphy for bamboos, whereas many well-known, widely used features for diagnosing groups remain to be formally tested in a comprehensive phylogenetic framework. In this review, we investigate the use of anatomical and micromorphological features in defining and delimiting minor and major groups in Bambusoideae. A general description of the leaf blade as seen in cross-section and surface view is provided for the subfamily, as well as features commonly found in the three currently recognized tribes (Arundinarieae, Bambuseae and Olyreae) and their subtribes. Some features, including midrib vasculature, fusoid cells and stomatal apparatus, are discussed in the light of systematic and phylogenetic perspectives, along with a clarification of terminology. Illustrations of relevant features are also provided. This review allowed us to elucidate anatomical and micromorphological features useful in defining and delimiting lineages but also to highlight some research priorities in Bambusoideae.

A Fungal Elicitor of the Resistance Response in Wheat

1985 ◽  
Vol 40 (9-10) ◽  
pp. 743-744 ◽  
Author(s):  
Karl-Heinz Kogel ◽  
Birgit Heck ◽  
Gerd Kogel ◽  
Bruno Moerschbacher ◽  
Hans-Joachim Reisener
Keyword(s):  
Stem Rust ◽  
Active Compound ◽  
Germ Tube ◽  
Phenylpropanoid Pathway ◽  
Metabolic Changes ◽  
Fungal Elicitor ◽  
Wheat Stem Rust ◽  
Mesophyll Cells ◽  
Resistance Response ◽  
Wheat Leaves

Abstract An elicitor of the lignification response in wheat leaves was isolated from the germ-tube walls of wheat stem rust. The active compound causes metabolic changes typically correlated with the resistance response, i.e. the formation of lignin or lignin-like polymers in affected epidermal and mesophyll cells and the increased activities of enzymes involved in the phenylpropanoid-pathway.

scholarly journals Analysis of Draft Genome Sequences of Two New Pantoea Strains Associated with Wheat Leaf Necrotic Tissues Caused by Xanthomonas translucens Reveals Distinct Species

2020 ◽  
Vol 9 (30) ◽  
Author(s):  
Alexandre Malette ◽  
Renlin Xu ◽  
Suzanne Gerdis ◽  
Sylvia I. Chi ◽  
Greg C. Daniels ◽  
...  
Keyword(s):  
Draft Genome ◽  
Distinct Species ◽  
Whole Genome ◽  
Genome Sequences ◽  
Coding Sequences ◽  
Content Type ◽  
Wheat Leaf ◽  
Xanthomonas Translucens ◽  
Wheat Leaves

ABSTRACT We report whole-genome sequences of two new Pantoea strains (DOAB1048 and DOAB1050) isolated from necrotic wheat leaves caused by Xanthomonas translucens. The draft genome sequences of DOAB1048 and DOAB1050 consist of 52 and 57 scaffolds and have sizes of 4,795,525 bp and 4,962,883 bp with 4,418 and 4,517 coding sequences, respectively.

scholarly journals Presence of ice-nucleating Pseudomonas on wheat leaves promotes Septoria tritici blotch disease (Zymoseptoria tritici) via a mutually beneficial interaction

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Helen N. Fones
Keyword(s):  
Frost Damage ◽  
Ice Nucleation ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Zymoseptoria Tritici ◽  
Bacterial Populations ◽  
Wheat Leaf ◽  
Ina Bacteria ◽  
Wheat Leaves ◽  
Important Disease

Abstract Zymoseptoria tritici causes Septoria tritici blotch (STB) of wheat, an economically important disease causing yield losses of up to 10% despite the use of fungicides and resistant cultivars. Z. tritici infection is symptomless for around 10 days, during which time the fungus grows randomly across the leaf surface prior to entry through stomata. Wounded leaves show faster, more extensive STB, suggesting that wounds facilitate fungal entry. Wheat leaves also host epiphytic bacteria; these include ice-nucleating (INA+) bacteria, which induce frost damage at warmer temperatures than it otherwise occurs. Here, STB is shown to be more rapid and severe when wheat is exposed to both INA+ bacteria and sub-zero temperatures. This suggests that ice-nucleation-induced wounding of the wheat leaf provides additional openings for fungal entry. INA+ bacterial populations are shown to benefit from the presence of Z. tritici, indicating that this microbial interaction is mutualistic. Finally, control of INA+ bacteria is shown to reduce STB.

THE ENZYMICALLY CATALYZED OXIDATION OF INDOLEACETIC ACID

1956 ◽  
Vol 34 (6) ◽  
pp. 905-926 ◽  
Author(s):  
E. R. Waygood ◽  
Ann Oaks ◽  
G. A. Maclachlan
Keyword(s):  
Indoleacetic Acid ◽  
Maleic Hydrazide ◽  
Organic Peroxide ◽  
Horse Radish Peroxidase ◽  
Reaction Sequence ◽  
Leaf Extracts ◽  
Naturally Occurring ◽  
Wheat Leaf ◽  
Wheat Leaves ◽  
Catalyzed Oxidation

Dialyzed wheat leaf extracts, catalase, and horse-radish peroxidase catalyze the decarboxylation and oxidation of indoleacetic acid at pH 5.0–6.0 in the presence of critical concentrations of manganese and monohydric phenols or resorcinol. The equivalent of 1 mole of carbon dioxide is liberated and 1 mole of oxygen consumed per mole of substrate. Manganic ions formed by a phenol–peroxidase–peroxide system initiate the decarboxylation and oxidation. A naturally occurring ether soluble factor from wheat leaves, and maleic hydrazide, can substitute for the active phenols. Catechol, hydroquinone, pyrogallol, seopoletin, and riboflavin, etc. competitively inhibit the oxidation. The nature of the active peroxide is discussed and a reaction sequence involving an organic peroxide or radical rather than hydrogen peroxide is submitted as being a possibility.

THE PHYSIOLOGY OF HOST–PARASITE RELATIONS: XVIII. DISTRIBUTION OF TRITIUM-LABELLED CYTIDINE, URIDINE, AND LEUCINE IN WHEAT LEAVES INFECTED WITH THE STEM RUST FUNGUS

1967 ◽  
Vol 45 (5) ◽  
pp. 555-563 ◽  
Author(s):  
P. K. Bhattacharya ◽  
Michael Shaw
Keyword(s):  
Stem Rust ◽  
Rust Fungus ◽  
Host Cells ◽  
Fungal Mycelium ◽  
Puccinia Graminis ◽  
Mesophyll Cells ◽  
Wheat Leaves ◽  
Host Parasite

Wheat leaves were detached 6 days after inoculation with the stem rust fungus (Puccinia graminis var. tritici Erikss. and Henn.) and fed with tritiated leucine, cytidine, uridine, or thymidine. Mesophyll cells in infected zones incorporated more leucine into protein and more cytidine and uridine into RNA than did cells in adjacent uninfected tissue. Leucine, cytidine, and uridine were also heavily incorporated by fungal mycelium and developing uredospores. Grain counts over host nuclei in the infected zone were two to three-fold of those over nuclei in adjacent uninfected zones. There was no detectable incorporation of thymidinemethyl-3H into either the fungus or the host cells. The results are discussed.

QUALITATIVE AND QUANTITATIVE DETERMINATION OF THE WHEAT LEAF CARBOHYDRATES

1950 ◽  
Vol 28c (6) ◽  
pp. 754-779 ◽  
Author(s):  
D. W. A. Roberts
Keyword(s):  
Reducing Sugars ◽  
Degradation Products ◽  
Reducing Power ◽  
Insoluble Residue ◽  
Leaf Extracts ◽  
Wheat Leaf ◽  
Leaf Carbohydrates ◽  
Wheat Leaves ◽  
Reducing Substances ◽  
Fructose Determination

The nonreducing sugar in wheat leaves is probably entirely sucrose. It is the only abundant sugar. Free reducing sugars are absent, or almost absent from wheat leaves grown under the conditions described. The reducing power in the cleared alcoholic extracts of the leaves is, at least, partly due to degradation products of ascorbic acid. Other nonsugar reducing substances also are apparently present. The alcohol insoluble residue from wheat leaves contains little or no fructosan, dextrin, or starch at the two and one-half week old stage. Satisfactory methods for extracting and determining the sucrose are described. The following methods gave satisfactory results with wheat leaf extracts: the reducing power methods of Hanes and Somogyi after acid or preferably invertase hydrolysis, Ost's solution for fructose residues, the method of Neuberg and Strauss, the colorimetric resorcinol method. The latter method gives only approximate values for fructose residues unless the sugar concentration is high; the method is then fairly reliable. The following methods did not give satisfactory results: Hanes and Somogyi methods for free reducing sugars initially present in the extract, the hypoiodite titration for aldose sugars, and Sieben's method for fructose determination.

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