STUDIES ON THE FUSARIA WHICH CAUSE WILT IN MELONS: I. THE OCCURRENCE AND DISTRIBUTION OF RACES OF THE MUSKMELON AND WATERMELON FUSARIA AND A HISTOLOGICAL STUDY OF THE COLONIZATION OF MUSKMELON PLANTS SUSCEPTIBLE OR RESISTANT TO FUSARIUM WILT

1958 ◽  
Vol 36 (3) ◽  
pp. 393-410 ◽  
Author(s):  
James Reid
Keyword(s):  
Host Plants ◽  
Histological Study ◽  
Effect Of Temperature ◽  
Infested Soil ◽  
Time Intervals ◽  
Cortical Cells ◽  
Susceptible Host ◽  
Host Parasite ◽  
Respective Host ◽  
Comparable Time

It has been shown that more than one type of isolate of both the muskmelon Fusarium and the watermelon Fusarium occur naturally in infested soil. The isolates of both organisms could be divided into many cultural races, depending on the number of isolations made. Among these cultural races differences were demonstrated in their ability to establish successful host–parasite relationships with their respective host plants. The field reactions of various host varieties were shown to be a function of the races present in the soil at a given time. Fluctuations in the relative frequency of the races present in a field have been shown to occur, as well as changes in the races present.The muskmelon wilt organism penetrated a susceptible host variety between cells in the region of elongation. The cortex was then colonized intercellularly, later intracellularly. The fungus then penetrated the stele, establishing itself in the vessels. Eventually hyphae were present throughout the vessels and later passed out to infect stelar and cortical tissues at various loci.The fungus also invaded the primary meristem intercellularly, later intracellularly, and established itself in young protoxylem vessels or developing cortical cells. Penetration also occurred through tears in the cortex caused by developing secondary roots.Colonization of a resistant host occurred in the same manner, but there was always less fungus in the resistant host than in the susceptible host after comparable time intervals. This difference could not be correlated with the morphology of the resistant host.The effect of temperature on colonization appeared to be on the aggressiveness of the parasite, rather than on the susceptibility of the host.

scholarly journals Effect of Temperature on and Histopathology of the Interaction Between Meloidogyne incognita and Thielaviopsis basicola on Cotton

1999 ◽  
Vol 89 (8) ◽  
pp. 613-617 ◽  
Author(s):  
N. R. Walker ◽  
T. L. Kirkpatrick ◽  
C. S. Rothrock
Keyword(s):  
Meloidogyne Incognita ◽  
Vascular Tissue ◽  
Root Surface ◽  
Effect Of Temperature ◽  
Infested Soil ◽  
Thielaviopsis Basicola ◽  
Root Knot Nematode ◽  
Cortical Cells ◽  
Node Ratio ◽  
Cotton Seeds

Controlled environments were used to study the relationship between the root-knot nematode (Meloidogyne incognita) and Thielaviopsis basicola on cotton. Temperature treatments were continuous 20, 24, and 28°C or two cyclic linear regimes with ranges of 14 to 32 or 18 to 28°C over 24 h. Cotton seeds were planted in fumigated soil infested with T. basicola, M. incognita, or both. After 42 days, pathogen effects on plant growth and pathogen development were evaluated. Histology was conducted on roots collected 14, 28, and 42 days after planting in the continuous 24°C treatment. Reductions in plant height-to-node ratio and total fresh weight were observed for soils infested with both pathogens compared with the control or with soils infested with either pathogen, except for M. incognita-infested soil at 28°C. T. basicola reduced root galling and reproduction of the nematode at all temperatures. Vascular discoloration caused by T. basicola was greater in the presence of M. incognita compared with that by T. basicola alone. At 2 and 4 weeks, histological studies showed that plants grown in all T. basicola-infested soils contained chlamydospore chains on the root surface and in cortical cells. The fungus was not observed inside the vascular cylinder. Roots from 4-week-old plants from soils infested with T. basicola and M. incognita showed fungal sporulation in vascular tissue and localized necrosis of vascular tissue adjacent to the nematodes. At 6 weeks, plants grown in soil infested with T. basicola alone exhibited no remaining cortical tissue and no evidence of vascular colonization by the fungus. Six-week-old plants grown in T. basicola + M. incognita-infested soils exhibited extensive vascular necrosis and sporulation within vascular tissue. These studies suggest that coinfection expands the temperature ranges at which the pathogens are able to cause plant damage. Further, M. incognita greatly increases the access of T. basicola to vascular tissue.

scholarly journals Mistletoe Contains Higher Secondary Metabolites Than the Host Plant at the Host-Parasite Interface: Insights From Tapinanthus Globiferus Collected In Enugu, Nigeria

2021 ◽  
Author(s):  
Godswill Ajuziogu ◽  
G C Agbo ◽  
Reginald Njokuocha ◽  
Anthony Nweze ◽  
Eugene O Ojua ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Host Plant ◽  
Bioactive Compounds ◽  
Host Plants ◽  
Parasitic Plant ◽  
Phytochemical Content ◽  
Host Parasite ◽  
Respective Host

Abstract Background: This study aims at evaluating the phytochemicals composition at the host-parasite interfaces of parasitic plant Tapinanthus globiferus (mistletoe) and four host plants. Wood tissues of the hosts and the parasite at the host-parasite interface were collected and analyzed to determine the presence secondary metabolites. Results: The result showed that flavonoids, saponins, and glycosides were present in the plants and parasite samples. The results revealed higher concentration of flavonoids (P < 0.05) in the parasite of C. acuminata (1190.33 ± 48.23 mgQE/g) and P. macrophylla (1482.55 ± 31.35 mgQE/g) than in the host plant. Saponins was significantly (P < 0.05) higher in the parasites as compared to their respective host. Conclusion: At the host-parasite interface, significantly higher phytochemicals in the wood portion of T. globiferus was observed as compared to the host plants wood; however, the variability in phytochemical content of T. globiferus is dependent on the host. Therefore, milestoe would be a better source of bioactive compounds with high medicinal values than their host plants if explored further.

Refining the Life Cycle of Plasmodiophora brassicae

2020 ◽  
Vol 110 (10) ◽  
pp. 1704-1712 ◽  
Author(s):  
Lijiang Liu ◽  
Li Qin ◽  
Zhuqing Zhou ◽  
Wilhelmina G. H. M. Hendriks ◽  
Shengyi Liu ◽  
...  
Keyword(s):  
Life Cycle ◽  
Plasmodiophora Brassicae ◽  
Secondary Infection ◽  
Life Stage ◽  
Infection Process ◽  
Epidermal Cells ◽  
Sexual Life ◽  
Cortical Cells ◽  
Susceptible Host ◽  
Clubroot Disease

As a soilborne protist pathogen, Plasmodiophora brassicae causes the devastating clubroot disease on Brassicaceae crops worldwide. Due to its intracellular obligate biotrophic nature, the life cycle of P. brassicae is still not fully understood. Here, we used fluorescent probe-based confocal microscopy and transmission electron microscopy (TEM) to investigate the infection process of P. brassicae on the susceptible host Arabidopsis under controlled conditions. We found that P. brassicae can initiate the primary infection in both root hairs and epidermal cells, producing the uninucleate primary plasmodium at 1 day postinoculation (dpi). After that, the developed multinucleate primary plasmodium underwent condensing and cytoplasm cleavage into uninucleate zoosporangia from 1 to 4 dpi. This was subsequently followed by the formation of multinucleate zoosporangia and the production of secondary zoospores within zoosporangium. Importantly, the secondary zoospores performed a conjugation in the root epidermal cells after their release. TEM revealed extensive uninucleate secondary plasmodium in cortical cells at 8 dpi, indicating the establishment of the secondary infection. The P. brassicae subsequently developed into binucleate, quadrinucleate, and multinucleate secondary plasmodia from 10 to 15 dpi, during which the clubroot symptoms appeared. The uninucleate resting spores were first observed in the cortical cells at 24 dpi, marking the completion of a life cycle. We also provided evidence that the secondary infection of P. brassicae may represent the diploid sexual life stage. From these findings, we propose a refined life cycle of P. brassicae which will contribute to understanding of the complicated infection biology of P. brassicae.

Disappearance as a Protective Factor

1971 ◽  
Vol 2 (1) ◽  
pp. 41-i ◽  
Author(s):  
Carl H. Lindroth
Keyword(s):  
Protective Factor ◽  
Chemical Nature ◽  
Similar Case ◽  
Effective Protection ◽  
Flea Beetles ◽  
Host Parasite Relationship ◽  
Parasite Relationship ◽  
Host Parasite ◽  
African Genus ◽  
Respective Host

AbstractCertain species of genus Lebia (Carabidae) are strikingly similar in color to species of flea-beetles (Alticinae, Chrysomelidae) with which they are regularly associated on the foodplants of the latter. A host-parasite relationship is suggested. Other chrysomelids, known as hosts of a Lebia, are not imitated. It is proposed that the jumping habit of the flea-beetles is an effective protection against certain birds and that they are imitated by the accompanying Lebia for this reason. The situation is interpreted as a case of Bates'ian mimicry. A similar case is the striking resemblance between two species of the African genus Lebistina and their respective host, flea-beetles of the genus Diamphidia. These are used by the bushmen for the production of arrow-poison. It is therefore assumed that here the protection is of a chemical nature.

scholarly journals Effect of Temperature on Plant Resistance to Arthropod Pests

2020 ◽  
Vol 49 (3) ◽  
pp. 537-545
Author(s):  
James R Nechols ◽  
Ashley R Hough ◽  
David C Margolies ◽  
John R Ruberson ◽  
Brian P McCornack ◽  
...  
Keyword(s):  
Plant Resistance ◽  
Indirect Effects ◽  
Host Plants ◽  
Structural Characteristics ◽  
Effect Of Temperature ◽  
Future Research ◽  
Experimental Approaches ◽  
Arthropod Pests ◽  
Effects Of Temperature ◽  
Effective Use

Abstract Temperature has a strong influence on the development, survival, and fecundity of herbivorous arthropods, and it plays a key role in regulating the growth and development of their host plants. In addition, temperature affects the production of plant secondary chemicals as well as structural characteristics used for defense against herbivores. Thus, temperature has potentially important implications for host plant resistance. Because temperature directly impacts arthropod pests, both positively and negatively, distinguishing direct effects from indirect effects mediated through host plants poses a challenge for researchers and practitioners. A more comprehensive understanding of how temperature affects plant resistance specifically, and arthropod pests in general, would lead to better predictions of pest populations, and more effective use of plant resistance as a management tactic. Therefore, the goals of this paper are to 1) review and update knowledge about temperature effects on plant resistance, 2) evaluate alternative experimental approaches for separating direct from plant-mediated indirect effects of temperature on pests, including benefits and limitations of each approach, and 3) offer recommendations for future research.

Penetration and migration routes of Schistosoma japonicum miracidia in the snail Oncomelania hupensis

Parasitology ◽  
1991 ◽  
Vol 103 (1) ◽  
pp. 77-83 ◽  
Author(s):  
M. Y. Xia ◽  
J. Jourdane
Keyword(s):  
Spatial Distribution ◽  
Schistosoma Japonicum ◽  
Histological Study ◽  
Circulatory System ◽  
Selective Advantage ◽  
Oncomelania Hupensis ◽  
Migration Routes ◽  
Branchial Cavity ◽  
And Migration ◽  
Host Parasite

The routes of penetration and the strategies of invasion of Schistosoma japonicum miracidia in the snail vector Oncomelania hupensis were observed in a histological study. In all species of the genus Schistosoma, it is usually assumed that the miracidia achieve penetration through the tegument. Our results showed that at least 57% of S. japonicum miracidia penetrated the snail by natural openings (branchial cavity, mouth and rectum). Throughout the invasion phase, the larvae were observed in all the tissues and organs with the exception of the genital gland. The spatial distribution of parasites in the snail revealed that the migration towards the visceral organs such as the kidney, heart and sinuses (which are the most usual microhabitats of the mother sporocysts of S. japonicum) appeared to take place via the circulatory system. Using natural openings as routes for penetration probably provides a selective advantage in a host–parasite system in which the target mollusc is amphibious: we presume that the miracidia inside these natural openings are protected against desiccation when the snail leaves the water, and that they can subsequently invade the tissues.

GROUPING OF ISOLATES OF A LOW-TEMPERATURE BASIDIOMYCETE ON THE BASIS OF CULTURAL BEHAVIOR AND PATHOGENICITY

1961 ◽  
Vol 39 (2) ◽  
pp. 297-306 ◽  
Author(s):  
E. W. B. Ward ◽  
J. B. Lebeau ◽  
M. W. Cormack
Keyword(s):  
Low Temperature ◽  
Host Plants ◽  
Type A ◽  
Effect Of Temperature ◽  
Western Canada ◽  
Type B ◽  
Highly Pathogenic ◽  
Cultural Behavior ◽  
Type C ◽  
Ph Range

Isolates of an unidentified low-temperature basidiomycete, associated with snow mold in Western Canada, were divided into three types, A, B, and C, on the basis of their general cultural appearance. Support for this classification was obtained when representative isolates of each type were examined to determine: the effect of temperature and pH on growth; tolerance of antibiotics and HCN; ability to liberate HCN in culture and in the host plant; pathogenicity.Type A isolates grew slowly under most conditions and were least tolerant of the extremes of temperature and pH employed, moderately inhibited by antibiotics, and strongly inhibited by HCN. They produced HCN in large quantities in host plants and none in culture. They were moderately pathogenic on grass and highly pathogenic on alfalfa. Type B isolates grew somewhat more rapidly than type A, especially at the upper and lower temperatures, and grew over a wider pH range. These isolates were more tolerant of antibiotics and HCN. They produced smaller quantities of HCN than type A in infected alfalfa plants but released large amounts in culture. They were less pathogenic than type A on alfalfa but similarly pathogenic on grass. Type C isolates were fast-growing forms which were strongly inhibited by antibiotics and HCN. They did not liberate HCN under any conditions and were not pathogenic.

scholarly journals Testing the Role of Habitat Isolation among Ecologically Divergent Gall Wasp Populations

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Scott P. Egan ◽  
Glen R. Hood ◽  
James R. Ott
Keyword(s):  
Reproductive Isolation ◽  
Assortative Mating ◽  
Host Plants ◽  
Habitat Preferences ◽  
Habitat Isolation ◽  
Native Plant ◽  
Gall Wasp ◽  
Quercus Virginiana ◽  
Respective Host

Habitat isolation occurs when habitat preferences lower the probability of mating between individuals associated with differing habitats. While a potential barrier to gene flow during ecological speciation, the effect of habitat isolation on reproductive isolation has rarely been directly tested. Herein, we first estimated habitat preference for each of six populations of the gall waspBelonocnema treataeinhabiting eitherQuercus virginianaorQ. geminata. We then estimated the importance of habitat isolation in generating reproductive isolation betweenB. treataepopulations that were host specific to eitherQ. virginianaorQ. geminataby measuring mate preference in the presence and absence of the respective host plants. All populations exhibited host preference for their native plant, and assortative mating increased significantly in the presence of the respective host plants. This host-plant-mediated assortative mating demonstrates that habitat isolation likely plays an important role in promoting reproductive isolation among populations of this host-specific gall former.

scholarly journals Kinetics of NiO and NiCl2Hydrogen Reduction as Precursors and Properties of Produced Ni/Al2O3and Ni-Pd/Al2O3Catalysts

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Miroslav Sokić ◽  
Željko Kamberović ◽  
Vesna Nikolić ◽  
Branislav Marković ◽  
Marija Korać ◽  
...  
Keyword(s):  
Metal Content ◽  
Hydrogen Reduction ◽  
Effect Of Temperature ◽  
Synthesis Process ◽  
Reduction Temperature ◽  
Time Intervals ◽  
Reduction Processes ◽  
Calcination Step ◽  
Before And After ◽  
Kinetics Of

The objects of this investigation were the comparative kinetic analysis of the NiO and NiCl2reduction by hydrogen during an induction period and elimination of the calcination during the synthesis of Ni/Al2O3catalysts. The effect of temperature and time on NiO and NiCl2reduction degrees was studied. Avrami I equation was selected as the most favorable kinetic model and used to determine activation energy of the NiO and NiCl2reduction for the investigated temperature range (623–923 K) and time intervals (1–5 minutes). The investigation enabled reaching conclusions about the reaction ability and rate of the reduction processes. Afterward, Ni/Al2O3catalysts were obtained by using oxide and chloride precursor for Ni. The catalysts were supported on alumina-based foam and prepared via aerosol route. Properties of the samples before and after low-temperature hydrogen reduction (633 K) were compared. Obtained results indicated that the synthesis of Ni/Al2O3catalysts can be more efficient if chloride precursor for Ni is directly reduced by hydrogen during the synthesis process, without the calcination step. In addition, Ni-Pd/Al2O3catalysts with different metal content were prepared by using chloride precursors. Lower reduction temperature was utilized and the chlorides were almost completely reduced at 533 K.

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