PARASITISM IN PHOLISMA (LENNOACEAE): II. ANATOMICAL ASPECTS

1967 ◽  
Vol 45 (7) ◽  
pp. 1155-1162 ◽  
Author(s):  
Job Kuijt
Keyword(s):  
Lateral Roots ◽  
Sieve Tube ◽  
Cambial Activity ◽  
Root Cap ◽  
Xylem Parenchyma ◽  
Vessel Elements ◽  
Xylem Elements ◽  
Host Tissues

The anatomy of roots and haustoria of Pholisma depressum is detailed. Lignified xylem consists of vessel elements only, and is associated with some xylem parenchyma. Sieve tube members exist in both the stem and the root. The pilot root is characterized by a restriction of cambial activity to the primary phloem regions, thus resulting in 3–5 bundle-like structures in older roots. From the protoxylem points between these bundles vascular flanges extend radially outward. The steles of lateral roots are extensions of these vascular flanges. A root cap is recognizable but very thin.The endophyte is a lobed organ with sinuous and irregular vascular strands lacking any phloem-like tissues. Strands, occasionally uniseriate, invade adjacent host tissues, usually in phloem-producing regions of the host cambium. These strands establish xylem-to-xylem contact, but are parallel to host xylem elements. They may subsequently become partially encapsuled by the latter. No radial sinkers exist.The nuclei of the endophyte show a more or less permanent type of heteropycnosis, the significance of which is unknown.A comparison of the parasitism of Lennoaceae and Orobanchaceae yields a number of significant differences in the structure and development of roots and haustoria.

The occurrence and ontogeny of transfer cells associated with lateral roots and root nodules in Leguminosae

1979 ◽  
Vol 57 (23) ◽  
pp. 2583-2602 ◽  
Author(s):  
William Newcomb ◽  
R. L. Peterson
Keyword(s):  
Nitrogen Fixation ◽  
Rhizobium Leguminosarum ◽  
Root Nodules ◽  
Lateral Roots ◽  
Transfer Cells ◽  
Xylem Parenchyma ◽  
Cortical Cells ◽  
Nitrogenous Compounds ◽  
Wall Ingrowths ◽  
Xylem Elements

Xylem parenchyma transfer cells are present in the stele of the root tissue adjacent to emergent effective root nodules of garden pea (Pisum sativum), red kidney bean (Phaseolus vulgaris), broad bean (Vicia faba), soybean (Glycine max), and mung bean (Vigna radiata), two types of ineffective pea nodules, and emergent lateral roots of pea. The xylem parenchyma transfer cells contain many polyribosomes and mitochondria near the wall ingrowths which are located adjacent to pits in the xylem elements. Pericycle transfer cells also occur in the three types of pea nodules. In effective pea nodules wall ingrowths begin to form in the pericycle cells 5 days after inoculation with Rhizobium leguminosarum; at this stage rhizobia are only present in the root hair but the cortical cells have enlarged and some have undergone mitosis. The wall ingrowths begin to form in the xylem parenchyma cells 7–8 days after inoculation or the approximate time that rhizobia begin to be released from the infection thread. In both instances the wall ingrowths begin to form before the onset of dinitrogen reduction although previous workers have suggested that a flux of nitrogenous compounds (containing fixed N) induces their formation. The development of wall ingrowths in ineffective pea nodules also occurs independently of nitrogen fixation. Similarly, the wall ingrowths located near soybean nodules also begin to develop before the onset of nitrogen fixation.

DEVELOPMENTAL STUDIES ON EUPHORBIA ESULA L.: MORPHOLOGY OF THE ROOT SYSTEM

1963 ◽  
Vol 41 (5) ◽  
pp. 579-589 ◽  
Author(s):  
M. V. S. Raju ◽  
T. A. Steeves ◽  
R. T. Coupland
Keyword(s):  
Root System ◽  
Lateral Roots ◽  
Primary Root ◽  
Cambial Activity ◽  
Euphorbia Esula ◽  
Developmental Studies ◽  
Limited Growth ◽  
Mode Of Reproduction ◽  
Shoot Buds ◽  
Adverse Conditions

The significance of Euphorbia esula L. as a weed is related to its capacity to persist under adverse conditions and to its mode of reproduction. In both these properties, the root system plays an important role. The root system is initially established by seedlings. The seedling has a vigorous primary root with extensive longitudinal growth and considerable cambial activity. Such a root has been designated a "long" root. By contrast, the first lateral roots produced on the primary root have limited growth and no cambial activity. These roots have been termed "short" roots. Thus, the seedling exhibits a "heterorhizic" pattern. Lateral long roots also arise on the primary root of seedlings but their origin is delayed until cambial activity has begun. Such lateral long roots arise much earlier on seedlings growing in denuded areas than on those growing in areas covered by dense vegetation. The mature root system is described in terms of horizontal and vertical long roots, which make up the conspicuous framework of the system, and of the short roots which they produce. Long roots produce shoot-buds and the origin of these structures is delayed until cambial activity has started. Short roots do not give rise to shoot-buds. Cambial activity in long roots appears to be connected with bud production and its absence in short roots probably underlies their inability to produce buds.L'importance de Euphorbia esula L. comme mauvaise herbe est connexé a son capacité de persister dans les situations hostiles et à sa methode de reproduction. Dans ces deux caractéristiques, le système des racines a une signification profunde. Initialement le système des racines s'établit dans le semis. Le semis a une racine primaire très forte avec beaucoup de croissance longitudinale et avec une activité considérable du cambium. Une racine de cette espèce s'appelle une "longue" racine (long root). Par contre, les premières racines latérales que poussent sur la racine primaire ont croissance limité et aucun activité du cambium. Ces racines s'appellent les "courtes" racines (short roots). De cette façon, le semis montre un dessin "heterorhizique" (heterorhizic). Les longues racines latérales ont aussi leur origine sur la racine primaire du semis, mais l'origine est retardé jusqu'au commencement de l'activité du cambium. Les racines de cette espèce apparaissent beaucoup plus tôt sur les semis qui sont situés en terre sans autre végétation, que sur ceux qui sont situés au milieu des autres plantes. Le système adulte des racines se décrit sous forme des longues racines de l'espèce horizontale et verticale, lesquelles constituent la charpente bien visible du système, et des courtes racines que sont produites par les longues racines. Les longues racines produisent les bourgeons, mais l'origine des bourgeons est retardé jusqu'au commencement de l'activité du cambium dans les racines. Les courtes racines ne produisent pas les bourgeons. Il paraît que l'activité du cambium dans les longues racines soit corrélative avec l'initiation des bourgeons et l'absence du cambium dans les courtes racines explique probablement leur incapacité à produire les bourgeons.

Comparative Structure Of Vascular Cambium And Its Derivatives In Some Species Of Sterculia

IAWA Journal ◽  
1996 ◽  
Vol 17 (3) ◽  
pp. 311-318 ◽  
Author(s):  
K. S. Rao ◽  
Kishore S. Rajput ◽  
T. Srinivas
Keyword(s):  
Sieve Tube ◽  
Vascular Cambium ◽  
The South ◽  
Structural Variations ◽  
Axial Parenchyma ◽  
Vessel Elements ◽  
Comparative Structure ◽  
The Mean ◽  
Cambial Cells ◽  
Sheath Cells

Structural variations in cambium, xylem and phloem collected from main trunks of Sterculia colorata, S. alata, S. villosa, S. urens and S. foetida growing in the South Dangs forests were studied. In all five species, the cambium was storied with variations in the length of fusiform cambial cells. Compared to other species S. foetida had the longest and S. urens the shortest fusiform cambial cells. Cambial rays in all the species were compound (tall) and heterocellular with sheath cells. Their height and width were maximal in S. foetida and in S. villosa respectively. In all the species the storied nature of fusiform cambial cells was maintained in derivative cells that developed into sieve tube elements; vessel elements and axial parenchyma of both phloem and xylem. However, fibres of phloem and xylem were nonstoried. The dimensions of elements in phloem and xylem varied among the species. The variation in the mean length of sieve tube elements and vessel members coincided with that of fusiform cambial cells.

RESPONSE OF NEAR-ISOGENIC PEA CULTIVARS TO INFECTION BY Fusarium oxysporum f. sp. pisi RACES 1 AND 5

1989 ◽  
Vol 69 (4) ◽  
pp. 1335-1346 ◽  
Author(s):  
M. CHARCHAR ◽  
J. M. KRAFT
Keyword(s):  
Fusarium Oxysporum ◽  
Lateral Roots ◽  
Dominant Gene ◽  
Fungal Growth ◽  
Resistance Response ◽  
Resistant Cultivars ◽  
Tap Root ◽  
Race 1 ◽  
Xylem Elements ◽  
Root Apices

Near-isogenic pea cultivars, differing by a single dominant gene for resistance (R) or susceptibility (S) to Fusarium oxysporum f. sp. pisi race 1 (’M410’-S, ’Vantage’-R) or race 5 (’Sundance’-S, ’Sundance II’-R), were evaluated for their response to infection. The response of resistant cultivars to each race was similar. Colonies of both races were isolated in higher numbers from tap and lateral root apices of susceptible as compared with resistant cultivars. Internal tap root and hypocotyl invasion occurred in all cultivars tested. However, lateral roots and stems of resistant cultivars were not infected as compared with susceptible lines. Surface colonization of tap and lateral roots of the resistant cultivars was significantly less than with the susceptible cultivars. Scanning electron microscopy revealed that gel-like material completely sealed off xylem elements in lateral roots, epicotyls, and aboveground stems of resistant cultivars. In contrast, intense mycelial invasion, without the formation of gels, occurred in susceptible cultivars. Conidial germination and germ-tube growth of both race 1 and race 5 were stimulated by xylem fluids from the susceptible, but not from the resistant cultivars. A resistance response based on physical containment and reduced fungal growth was evident.Key words: Fusarium wilt, host response, Pisum sativum

Cell deformities in bark and sapwood caused by Rhytidiella moriformis and Keissleriella emergens infections in poplar

1975 ◽  
Vol 53 (8) ◽  
pp. 780-783 ◽  
Author(s):  
Harry Zalasky
Keyword(s):  
Cell Plate ◽  
Balsam Poplar ◽  
Cell Plate Formation ◽  
Cell Structures ◽  
Outer Periphery ◽  
Bordered Pits ◽  
Vessel Elements ◽  
Plate Formation ◽  
Ray Cells ◽  
Host Tissues

The cambium of balsam poplar appeared to be stimulated by Rhytidiella moriformis and Keissleriella emergens infections of bark, colonized to the outer periphery of the phloem but not beyond. Instead of producing normal xylem in groups of four cells, it produced hyperplastic and hypoplastic deformed xylem, each group consisting of variable combinations of tracheids, vessel elements, and wood parenchyma. Deformities were accompanied by composite cell structures and rapid aging of thick-walled ray cells. Tracheids and vessel elements were branched, curvate, attenuate, and short. Vessel elements without perforations had more bordered pits arranged on all sides. Perforations, if present, were often lateral and not oriented for vertical transport of solutes. Morphogenetically, host tissues are believed to be chimeral, as evidenced by stunting, incomplete cell-plate formation, and hyperplasia and hypoplasia. Changes in structure of cells and tissues of the host were caused by both pathogens, but they occur over a larger surface area of the bark and sapwood on trees infected by R. moriformis in nature.

scholarly journals First Report of the Causal Agent of Huanglongbing (“Candidatus Liberibacter asiaticus”) Infecting Kumquat in Taiwan

Plant Disease ◽  
2006 ◽  
Vol 90 (10) ◽  
pp. 1360-1360 ◽  
Author(s):  
C.-H. Tsai ◽  
H.-J. Su ◽  
Y.-C. Liao ◽  
T.-H. Hung
Keyword(s):  
16S Rrna ◽  
Lateral Roots ◽  
Severe Disease ◽  
Intergenic Spacer ◽  
Sieve Tube ◽  
Causal Agent ◽  
Candidatus Liberibacter Asiaticus ◽  
Intergenic Spacer Region ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus

Huanglongbing (greening) disease caused by a nonculturable, phloem-limited bacterium is a severe disease of citrus. On the basis of the influence of temperature on host symptoms and the causal agent, this disease can be categorized as Asian caused by “Candidatus Liberibacter asiaticus”, African caused by “Ca. L. africanus”, and American caused by “Ca. L. americanus”. Kumquat (Fortunella margarita (Lour.) Swingle), a member of the Rutaceae is an economically important crop for export and local consumption in Taiwan. Recently, a Huanglongbing-like disease was found on kumquat in Yilan County, the largest kumquat-producing area in northeastern Taiwan. Even though the disease has been reported on Citrus spp. from Taiwan, it has never been reported on kumquat. Symptoms of infected kumquat were mottling, yellowing, hardening, and curling of leaves followed by premature defoliation, twig dieback, decay of feeder rootlets and lateral roots, and ultimately the death of the entire plant. Typical sieve-tube-restricted bacteria were observed in kumquat cells by electron microscopy (1). In addition, psyllid-transmission tests demonstrated that the Asian psyllid (Diaphorina citri) could transmit this bacterium to healthy kumquats. Positive bud graft transmissions were obtained to F. margarita, F. japonica (Thunb.) Swingle, F. obovata Hort. ex Tanaka, Luchen sweet orange (Citrus sinensis (L.) Osb.), and Wentan pummelo (C. maxima f. sp. butan Hay.). These inoculated plants showed symptoms in 3 to 8 months, and bacteria could be detected by polymerase chain reaction (PCR) using a common primer pair that amplified a 226-bp specific DNA fragment (2). For further molecular identification, the bacterial DNA was extracted from the inoculated plants and PCR was performed by using two sets of primers selected from the 16S rRNA region (GenBank Accession No. L22532) and 16S/23S intergenic spacer region (GenBank Accession No. AB019793). The expected DNA fragments of 1,389 bp and 862 bp were, respectively, amplified from symptomatic plants but not from healthy plants. The PCR products were cloned and sequenced (GenBank Accession Nos. DQ302750 and DQ207841). The 16S rRNA has 98 to 99% identity and 16S/23S intergenic spacer region has 99% identity to the corresponding region of “Ca. L. asiaticus” in GenBank. These molecular analyses confirm the presence of “Ca. L. asiaticus” in kumquat. Since Huanglongbing has been rarely reported naturally on kumquat, further analysis of this bacterium as a special strain of “Ca. L. asiaticus” is needed. References: (1) M. Garnier et al. Ann. Microbiol. 135A:169, 1984. (2) T. H. Hung et al. J. Phytopathol. 147:599, 1999.

scholarly journals Morphoanatomic changes in shoot and root apices of banana Williams (AAA, Musa sp.) cultured on different N6- benzyladenine concentrations

1969 ◽  
Vol 92 (1-2) ◽  
pp. 53-72
Author(s):  
Maribel Ramírez-Villalobos ◽  
Helga Lindorf ◽  
Eva De García
Keyword(s):  
Lateral Roots ◽  
Root Apex ◽  
Transitional Zone ◽  
Root Cap ◽  
Anatomic Structure ◽  
Musa Sp ◽  
Tunica Layer ◽  
Vitro Development ◽  
Root Apices

Structural evidence about the in vitro growth of the shoot apex (SA) and root apex (RA) of banana is for the most part lacking.This paper presents an analysis of the morphoanatomic events that occur in the in vitro development of the SA, RA and explants of banana Williams cultured under different N6-benzyladenine (BA) concentrations. We examined the SA of explants (8 mm X 1.5 mm, shoot tip with part of rhizome) grown on 0, 2.5 and 5 mg /L of BA for 0, 3, 6, 9 and 12 d, and also the first emergent root (1 to 1.5 cm long) from these explants. Samples were sectioned (10 to 12 µm) and stained with safranin-fast green. The SA showed a dome shape with tunica-corpus organization (a single tunica layer). SA diameters were larger for explants growing in BA (93.75 to 142.05 µm) than in those growing without the cytokinin (73.87 to 85.83 µm), except for the diameter on the sixth day (127.84 µm). The noncultured initial explant without culture reached a diameter of 164.78 µm. The SA showed a cambium-like transitional zone in explants cultured with 2.5 mg/L of BA on the ninth day. This concentration also induced the highest number of shoots per explant (2.19) in 35 days. RA growing in media without BA showed protoderm, ground meristem, procambium, initial cells and root cap whereas with BA procambium, fundamental meristem and root cap (compressed) were distinguished. Benzyladenine decreased the number and length of the roots, inhibited the formation of lateral roots, increased the time for root emergence and caused distortion in their anatomic structure.

scholarly journals Death of pastures syndrome: tissue changes in Urochloa hybrida cv. Mulato II and Urochloa brizantha cv. Marandu

2017 ◽  
Vol 77 (1) ◽  
pp. 97-107 ◽  
Author(s):  
N. G. Ribeiro-Júnior ◽  
A. P. R. Ariano ◽  
I. V. Silva
Keyword(s):  
Anatomical Study ◽  
Sieve Tube ◽  
Cortical Region ◽  
Forage Production ◽  
Aerenchyma Formation ◽  
Mato Grosso ◽  
Vessel Elements ◽  
Tissue Changes ◽  
Urochloa Brizantha ◽  
The Individual

Abstract The quality of forage production is a prerequisite to raising livestock. Therefore, income losses in this activity, primarily cattle raising, can result in the impossibility of economic activity. Through the qualitative and quantitative anatomical study of Urochloa hybrida cv. Mulato II and U. brizantha cv. Marandu, we searched for descriptions and compared changes in the individual vegetative body from populations with death syndrome pastures (DPS). Specimens were collected at different physiological stages from farms in northern Mato Grosso. After collection, the individuals were fixed in FAA50 and stored in 70% alcohol. Histological slides were prepared from the middle third of the sections of roots, rhizomes, and leaves, and the proportions and characteristics of tissues were evaluated in healthy, intermediate, and advanced stages of DPS. Changes were compared between cultivars. With the advancement of the syndrome, the following changes were observed: a more marked decrease in the length of roots in U. hybrida; disorganization of the cortical region of the roots and rhizome cultivars; fungal hyphae in roots and aerenchyma formation in U. hybrida; a decrease in sclerenchyma fiber proportions in roots and leaves; sclerification of the epidermis of U. brizantha rhizomes; and an increase in pericyclic fibers in U. hybrida. Furthermore, there was a decrease in the volume of epidermal cells of the abaxial face of the leaves of both cultivars, with a greater reduction in U. hybrida; a gradual decrease in thickness in the midrib of leaves similar to leaf mesophyll; conduction system obstructions; partial or total cell lysis in roots and rhizomes affected by the syndrome. Obstructions in sieve tube element and companion cells, and sometimes obstruction in xylem vessel elements. The evolution of DPS in cultivars was similar, but there were variations, arising probably from the physiological response to stress, such as aerenchyma formation in the root and increased pericycle in the rhizome of U. hybrida.

Variability in the Distribution of Middle Lamella Lignin in Secondary Vascular Tissues of Kenaf Stems

IAWA Journal ◽  
2014 ◽  
Vol 35 (1) ◽  
pp. 61-68
Author(s):  
Seung Gon Wi ◽  
Kwang Ho Lee ◽  
Hyeun Jong Bae ◽  
Byung Dae Park ◽  
Adya P. Singh
Keyword(s):  
Cell Walls ◽  
Secondary Xylem ◽  
Middle Lamella ◽  
Hibiscus Cannabinus ◽  
Secondary Phloem ◽  
Xylem Parenchyma ◽  
Vascular Tissues ◽  
Transmission Electron ◽  
Parenchyma Cells ◽  
Xylem Elements

Lignin in the middle lamella of the secondary xylem of angiosperms appears to be inhomogeneously distributed, based on studies where the focus is on a close examinantion of the middle lamella region of fibre cell walls by transmission electron microscopy (TEM). This is in contrast to the secondary xylem of gymnosperms which often display a more uniform distribution of lignin in the middle lamella of secondary xylem elements. The aim of our study was to undertake TEM examination of kenaf (Hibiscus cannabinus L.), an angiosperm plant mainly cultivated for its high quality secondary phloem fibres, to investigate lignin distribution in the middle lamella of secondary vascular tissues, including secondary phloem fibres. The middle lamella displayed considerable heterogeneity in the distribution of lignin in all lignified secondary vascular tissues, including xylem and phloem fibres, vessels and axial xylem parenchyma cells. The results provided evidence of lignin inhomogeneity in the secondary phloem fibres as well as in other lignified elements of kenaf vascular tissues, extending previous observations which were confined only to fibre cells.

Cambial activity in the young branches and peduncles of couroupita guianensis (lecythidaceae)

IAWA Journal ◽  
2014 ◽  
Vol 35 (3) ◽  
pp. 281-292
Author(s):  
Kishore S. Rajput ◽  
Amreen Saiyed ◽  
Vidya S. Patil ◽  
K.S. Rao
Keyword(s):  
Cell Division ◽  
Secondary Growth ◽  
Cambial Activity ◽  
Climatic Conditions ◽  
Flower Buds ◽  
Cambial Cell ◽  
Mature Leaves ◽  
Couroupita Guianensis ◽  
Dual Source ◽  
Xylem Elements

Peduncles of Couroupita guianensis Aubl. undergo extensive secondary growth, which is a rare and unexplored feature so far. In the present investigation seasonal behaviour of vascular cambium was studied in fruit-bearing peduncles and compared with the vegetative branches of similar diameter. In peduncles, the cambium remained active throughout the year. The number of cambium cells and differentiating xylem cells increased from May and reached a maximum in July-August. Although cambial growth occurred throughout the year, it was relatively sluggish in February despite the development of new leaves and ongoing extension growth. In contrast, cambial cell division in young branches initiated in February, peaked in the same months as peduncle cambium while cambial cell division and differentiation of xylem remained suspended from October to January. Cessation of cambial cell division in the branches during this period may be correlated with the presence of mature leaves. In both (branches and peduncle), rapid cell division and increase in the number of differentiating xylem elements in April-May is positively correlated with the development of flower buds and new leaves. The present anatomical investigation revealed that cambial activity in both peduncle and vegetative branches are independent of phenology and climatic conditions. In conclusion, we believe that variations in the number of differentiating cambium derivatives in peduncles benefits from a dual source of growth hormone supply, i.e. from developing new leaves and flower buds.

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