Host-pathogen relationship in tobacco plants with stems infected by Peronospora tabacina Adam

1960 ◽  
Vol 11 (1) ◽  
pp. 16 ◽  
Author(s):  
M Mandryk
Keyword(s):  
Secondary Xylem ◽  
Vascular System ◽  
Early Stage ◽  
Infected Leaf ◽  
Flowering Stage ◽  
Peronospora Tabacina ◽  
Axillary Shoots ◽  
Daily Temperature Range ◽  
Stem Infection ◽  
Nicotiana Tabacum L

Stem infection of tobacco (Nicotiana tabacum L. cv. Virginia Gold) with Peronospora tabacina Adam was established and its development studied. Mycelium of the pathogen spread from parenchyma tissue of the infected leaf blade into the vascular system of midrib and petiole and thence into the stem. In small seedlings mycelium was usually associated with all tissues and often killed the plant. In plants at the flowering stage necrosis was chiefly confined to the periphery of secondary xylem, the cambium, and the inner part of the external phloem region. As xylem aged it acted as a barrier to the spread of mycelium from external to internal phloem and to the pith. Cortex was not penetrated readily by the pathogen. When the pathogen became established in the cambium region of the stem at an early stage of plant growth, development of xylem was often inhibited. Such plants, when full grown, were brittle at the base and snapped off readily. Development of the pathogen in the stem was favoured by high humidity but was arrested by exposing the plants to benzol vapour, or to a daily temperature range of 75-105°F when humidity was not higher than 70 per cent. High temperature during the day followed by low temperature at night did not prevent spread of the pathogen from the leaves into the stem. Mycelium sometimes spread from infected stems into new axillary shoots with subsequent sporulation on leaves.

Stem infection of tobacco plants with three strains of Peronospora tabacina Adam

1966 ◽  
Vol 17 (1) ◽  
pp. 39 ◽  
Author(s):  
M Mandry
Keyword(s):  
Plant Growth ◽  
Vascular System ◽  
Original Strain ◽  
Resistant Line ◽  
Peronospora Tabacina ◽  
Highly Pathogenic ◽  
Tobacco Plants ◽  
Stem Infection ◽  
Probable Occurrence ◽  
Cool Conditions

The pathogenicity of three strains of Peronospora tabacina Adam., APT1, APT2, and APT3, in stems of tobacco plants and their effect on the development and survival of plants were determined. (1) APT1, APT2, and APT3 are highly pathogenic in stems of cv. Virginia Gold and in two varieties of Oriental tobacco. Stems of cv. SO1 plants (resistant line) are unaffected by the original strain APTl but are severely infected by the two new strains APT2 and APT3. (2) Severe stem infection developed in injected plants at a temperature of 15–25°C and R.H. higher than 80°. Mycelium of the pathogen rapidly invaded all stem tissues. Of affected plants, 40–75% were killed and the survivors remained dwarfed with small and severely wilted leaves. Under humid and cool conditions APTl and APT3 were more destructive than APT2. (3) Mild stem infection developed at a temperature of 20–30°C and R.H. not higher than 70%. Under these conditions APT2 was more pathogenic than APTl or APT3. The mycelium of the fungus was associated mainly with the vascular system. General plant growth and leaf areas were only slightly reduced. (4) It is concluded that present methods of controlling blue mould in tobacco plants need extension. Consideration should be given to breeding for resistance to stem infection with due regard to the two new strains of P. tabacina described in this paper and the probable occurrence of further physiologic strains of this pathogen in the future.

Studies of seed production in two Austrodanthonia grass cultivars

2002 ◽  
Vol 53 (11) ◽  
pp. 1197 ◽  
Author(s):  
G. M. Lodge
Keyword(s):  
Seed Germination ◽  
Seed Production ◽  
Early Stage ◽  
Early Flowering ◽  
Harvest Time ◽  
Flowering Stage ◽  
N Application ◽  
Factors Affecting ◽  
The Mean ◽  
Early Harvest

Studies were conducted in 1993–94 on 2 native grass cultivars, Austrodanthonia richardsonii (Link) H.P.�Linder (syn. Danthonia richardsonii Cashmore) cv. Taranna and A. bipartita (Link) H.P. Linder (syn. D. linkii Kunth) cv. Bunderra, to quantify the important morphological factors affecting seed production (as measured by seed weight, g/plant). Experiments also examined the influence of nitrogen (N) application and investigated the effects of time and method of harvest on seed production and subsequent germination. For both cultivars, inflorescence and floret number accounted for the highest proportion of the variation in seed production per plant (R2 = 0.873 and 0.686 for Taranna and Bunderra, respectively). Although N applied (0, 25, and 50 kg/ha) at the late vegetative or early flowering stage, or split applications at both times, had no significant effect (P > 0.05) on the seed production per plant of Taranna and Bunderra, further studies of N effects are required. In 1993 and 1994, time of inflorescence harvest and method of harvest had no significant effect on inflorescence number and seed production of Taranna and Bunderra and no significant effect on the subsequent germination of Bunderra seed. However, in 1993, harvesting at an early stage of flowering (10% of florets white and fluffy) reduced Taranna seed production by 17% compared with the mean and decreased (P < 0.05) seed germination by about 10%. In 1994, harvesting at early flowering (5% florets white and fluffy) reduced Taranna seed production by a mean of around 55% compared with harvesting at 50% maturity, and subsequent seed germination was also lower (P < 0.05) for the early harvest time. Application of 1 L/ha of paraquat (a.i. 200 g/L of paraquat dichloride) at mid-flowering to desiccate the crop in 1993 had no significant effect on the germination of Taranna and Bunderra caryopses. The implications of these data for commercial seed production are discussed.

scholarly journals Vascular Involvement in Rheumatoid Arthritis

2020 ◽  
Author(s):  
Alexandru Caraba ◽  
Stela Iurciuc ◽  
Mircea Iurciuc
Keyword(s):  
Rheumatoid Arthritis ◽  
Vascular System ◽  
Carotid Artery Disease ◽  
Early Stage ◽  
Macrovascular Disease ◽  
Vascular Involvement ◽  
Inflammatory Rheumatic Diseases ◽  
Artery Disease ◽  
The One ◽  
Peripheral Arterial

Rheumatoid arthritis (RA) represents the one of the most common inflammatory rheumatic diseases, which generates disability and significantly reduces the quality of life. RA can affect the vascular system, in addition to joint involvement. Vascular involvement increases the morbidity and mortality among these patients. Macrovascular disease, related to accelerated atherosclerosis, has a high prevalence among RA patients, in the form of carotid artery disease, ischemic heart disease, and peripheral arterial obstructive disease. Microvascular disease, studied in recent years by means of nailfold capillaroscopy, is present even in the early stage of RA evolution. Rheumatoid vasculitis can occur in severe forms of RA.

scholarly journals The bronchial vascular system in the dog

1931 ◽  
Vol 109 (762) ◽  
pp. 214-228 ◽  
Keyword(s):  
Vascular System ◽  
Early Stage ◽  
Preliminary Investigation ◽  
Systemic Circulation ◽  
Bronchial Tree ◽  
Bronchial Arteries ◽  
Arterial Blood ◽  
Two Systems ◽  
Chief Interest ◽  
The Moment

The distribution of the bronchial arteries (the vasa nutritia of Reisseissen) within the lung has been investigated by many anatomists but, beyond our knowledge that they are nutritional vessels to the bronchial tree (Reisseissen and Sömmering, 1808; Reisseissen, 1808, 1822 ; Luschka, 1863; Königstein, 1903), little is known of their significance for the maintenance of the normal functions of the lungs. At the moment their chief interest lies in the number of reports describing the changes in the bronchial blood vessels resulting from interference with the pulmonary vascular system and from lesions in the lungs. Two years ago Professor E. B. Verney and one of us (I. de B. D.) were conducting experiments in this laboratory which involved the separation of the pulmonary from the systemic circulation in the dog, the two systems being perfused by separate pumps. In one experiment it appeared that blood was being transferred from the aorta to the left auricle through the bronchial vascular system. It became desirable, therefore, to inquire into the conditions which govern the bronchial blood supply. At an early stage in this inquiry it was evident that, owing to the variations in the origin of the bronchial arteries, a study of the gross and minute anatomy of the bronchial vascular system in each perfusion experiment would be necessary if anything approaching a correct interpretation of our results was to be expected. As a preliminary investigation to our perfusion experiments, we have examined the bronchial vascular system in a number of animals and the results form the subject of this paper. In it are also incorporated the anatomical findings on the perfused lungs used for physiological investigations. We have concentrated our efforts on two main issues: the first, the arrangement of the bronchial arteries and veins with a view to setting up apparatus for perfusion of the bronchial arteries and the collection of the blood from the bronchial veins ; the second, an enquiry into possible arterial and venous communications between the bronchial and pulmonary vascular systems. It is clear that if arterial anastomotic channels exist between the two systems it will not be possible to separate completely the arterial blood of each.

scholarly journals Ethanol combined with coil embolisation for the treatment of arteriovenous malformations in a patient with Parkes Weber syndrome

2020 ◽  
Vol 102 (3) ◽  
pp. e54-e56
Author(s):  
Q Zhao ◽  
Lian Liu ◽  
Z Liao ◽  
Y Pan ◽  
Jingyan Liu ◽  
...  
Keyword(s):  
Arteriovenous Malformations ◽  
Vascular System ◽  
Early Stage ◽  
Therapeutic Option ◽  
Coil Embolisation ◽  
Weber Syndrome ◽  
Congenital Condition ◽  
Initial Procedure ◽  
Life Threatening

Parkes Weber syndrome is a rare congenital condition of the vascular system with severe symptoms and life-threatening complications. The challenge is to manage the arteriovenous malformations, and there is no consensus on optimal treatment. We report the case of an 18-year-old woman with Parkes Weber syndrome who was treated with ethanol combined with coil embolisation at an early stage. After two sessions of embolisation, a significant devascularisation was achieved. No sign of recurrence was observed two years after the initial procedure. The patient’s symptoms and signs were greatly relieved during the follow-up period. This case raises awareness of Parkes Weber syndrome and highlights the importance of timely intervention, as well as offering a promising therapeutic option for this condition.

scholarly journals A CDC42 Homologue in Claviceps purpurea Is Involved in Vegetative Differentiation and Is Essential for Pathogenicity

2005 ◽  
Vol 4 (7) ◽  
pp. 1228-1238 ◽  
Author(s):  
Jan Scheffer ◽  
Changbin Chen ◽  
Patrick Heidrich ◽  
Martin B. Dickman ◽  
Paul Tudzynski
Keyword(s):  
Vascular System ◽  
Early Stage ◽  
Ovarian Tissue ◽  
Wild Strain ◽  
Extended Period ◽  
Small Gtpase ◽  
Dominant Negative ◽  
Claviceps Purpurea ◽  
Cytoskeleton Organization ◽  
Colletotrichum Trifolii

ABSTRACT Claviceps purpurea, a biotrophic pathogen of cereals, has developed a unique pathogenic strategy including an extended period of unbranched directed growth in the host's style and ovarian tissue to tap the vascular system. Since the small GTPase Cdc42 has been shown to be involved in cytoskeleton organization and polarity in other fungi, we investigated the role of Cdc42 in the development and pathogenicity of C. purpurea. Expression of heterologous dominant-active (DA) and dominant-negative (DN) alleles of Colletotrichum trifolii in a wild strain of C. purpurea had significant impact on vegetative differentiation: whereas DA Ctcdc42 resulted in loss of conidiation and in aberrant cell shape, expression of DN Ctcdc42 stimulated branching and conidiation. Deletion of the endogenous Cpcdc42 gene was not lethal but led to a phenotype comparable to that of DN Ctcdc42 transformants. ΔCpcdc42 mutants were nonpathogenic; i.e., they induced no disease symptoms. Cytological analysis (light microscopy and electron microscopy) revealed that the mutants can penetrate and invade the stylar tissue. However, invasive growth was arrested in an early stage, presumably induced by plant defense reactions (necrosis or increased production of reactive oxygen species), which were never observed in wild-type infection. The data show a significant impact of Cpcdc42 on vegetative differentiation and pathogenicity in C. purpurea.

scholarly journals X .— The morphology and evolution of the ambulacrum in the echinoidea Holectypoida

1920 ◽  
Vol 209 (360-371) ◽  
pp. 377-480 ◽  
Keyword(s):  
Relative Position ◽  
General Type ◽  
Vascular System ◽  
Early Stage ◽  
Larval Life ◽  
Large Area ◽  
Central Topic ◽  
Original Title ◽  
Vital Functions

During the course of the work upon which the following pages are primarily based, the need for an ever-increasing width of scope has continually arisen. In its original conception the paper was to treat of the structure of the Holectypoida alone. Gradually the inevitable comparisons extended their range, until in its final form the work deals more or less completely with the ambulacral structure of all the orders of the Echinoidea, and includes far more argument of a general type than was first intended. Nevertheless, the original title has been retained. As in a map designed to show the position of a town, a large area of the surrounding district must needs be included, so that the roads which lead to, from, or past the place can be distinguished; thus, too, the relative position of the Holectypoid ambulacrum in the morphogenesis of Echinoid ambulacra can only be appreciated by description of the homologous structures which preceded, succeeded, or diverged from it in the course of evolution. Thus the title, though far from comprehending all the matter subjoined to it, is apt, in that it indicates the central topic towards which all the others converge and contribute. In the study of the Echinoidea, the ambulacra and their associated structures have always been recognised as affording taxonomic evidence of great value. Not only do the "avenues” of pores attract attention, in denuded tests, by their distinctness and diversity, but the extensions of the water-vascular system to which they give passage are concerned with many vital functions. Ambulacral plates are among the first to appear during the metamorphosis of an Echinoid pluteus, and the development of ambulacral projections from the hydrocoel marks an early stage in larval life. An ambulacrum consists of an even number of columns of plates (usually two), each one of which is perforated for the transmission of a “tube-foot.’' There are thus two features, more or less interdependent, that are available for study in fossil forms—the plates and the pores. But it is only within the last five decades that any consistent attempts at an understanding of the plating-structure of the Echinoid corona have been made; and even now systematic writers most frequently limit their descriptions of the ambulacra to the nature of the pores and the distribution of the ornament.

Structure and ontogeny of the fissured stems of Callaeum (Malpighiaceae)

IAWA Journal ◽  
2017 ◽  
Vol 38 (1) ◽  
pp. 49-66 ◽  
Author(s):  
Pablo A. Cabanillas ◽  
Marcelo R. Pace ◽  
Veronica Angyalossy
Keyword(s):  
Secondary Xylem ◽  
Vascular System ◽  
Secondary Growth ◽  
Natural Fracture ◽  
Production Rates ◽  
Axial Parenchyma ◽  
Parenchyma Cells ◽  
Ray Cells ◽  
Cambial Variant ◽  
Stem Development

Stem ontogeny and structure of two neotropical twining vines of the genus Callaeum are described. Secondary growth in Callaeum begins with a typical regular cambium that gradually becomes lobed as a result of variation in xylem and phloem production rates in certain portions of the stem aligned with stem orthostichies. As development progresses, lignified ray cells of the initially formed secondary xylem detach on one side from the adjacent tissues, forming a natural fracture that induces the proliferation of both ray and axial nonlignified parenchyma. At the same time, parenchyma proliferation takes place around the pith margin and generates a ring of radially arranged parenchyma cells. The parenchyma generated in this process (here termed disruptive parenchyma) keeps dividing throughout stem development. As growth continues, the parenchyma finally cleaves the lignified axial parts of the vascular system into several isolated fragments of different sizes. Each fragment consists of xylem, phloem and vascular cambium and is immersed in a ground matrix of disruptive parenchyma. The cambium present in each fragment divides anticlinally to almost encircle each entire fragment and maintains its regular activity by producing xylem to the centre of the fragment and phloem to the periphery. Additionally, new cambia arise within the disruptive parenchyma and produce xylem and phloem in various polarities, such as xylem to the inside and phloem to the outside of the stem, or perpendicularly to the original cambium. Unlike the very distinctive stem anatomical architecture resulting from this cambial variant in Callaeum, its secondary xylem and phloem exhibit features typical of lianas. These features include very wide conducting cells, abundant axial parenchyma, high and heterocellular rays and gelatinous fibres.

scholarly journals Identification of an Arabidopsis thaliana Mutation (vsm1) That Restricts Systemic Movement of Tobamoviruses

1998 ◽  
Vol 11 (7) ◽  
pp. 706-709 ◽  
Author(s):  
Robert T. Lartey ◽  
Soumitra Ghoshroy ◽  
Vitaly Citovsky
Keyword(s):  
Arabidopsis Thaliana ◽  
Viral Entry ◽  
Vascular System ◽  
Leaf Tissue ◽  
Systemic Infection ◽  
Viral Disease ◽  
Plant Viruses ◽  
Infected Leaf ◽  
Systemic Movement ◽  
Systemic Spread

Following inoculation, many plant viruses spread locally from cell to cell until they reach the vascular system, through which they then move to other parts of the plant, resulting in systemic infection. To isolate host genes involved in systemic transport of plant viruses, ethyl methanesulfonate-mutagenized Arabidopsis thaliana plants were screened for significant delays in the systemic movement of turnip vein clearing virus (TCVC). One such mutant, designated vsm1 (virus systemic movement), was identified. Unlike the wild-type plants, vsm1 did not develop viral disease and did not allow the systemic spread of the virus. The local viral movement within the inoculated vsm1 leaves, however, was not affected. TVCV systemic movement within the vsm1 plants was likely blocked at the step of viral entry into the host plant vasculature from the infected leaf tissue. vsm1 plants also restricted the systemic movement of another tobamovirus but not of an unrelated carmovirus.

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