Ultrastructure of susceptible, host resistant, and nonhost resistant interactions of alfalfa with Phytophthora megasperma

1984 ◽  
Vol 62 (1) ◽  
pp. 117-128 ◽  
Author(s):  
Sally A. Miller ◽  
Douglas P. Maxwell
Keyword(s):  
Cell Walls ◽  
Hyphal Growth ◽  
Host Cells ◽  
Compatible Interaction ◽  
Root Cells ◽  
Phytophthora Megasperma ◽  
Susceptible Host ◽  
Glycine Max L ◽  
Wall Appositions ◽  
Medicago Sativa L

Zoospores of Phytophthora megasperma Drechs. f. sp. medicaginis (Pmm), an alfalfa (Medicago sativa L.) pathogen, and P. megasperma f. sp. glycinea (Pmg), a pathogen of soybean (Glycine max (L.) Merr.), were used to inoculate alfalfa seedlings from the Pmm-susceptible cultivar 'Vernal' and the Pmm-resistant breeding line M193. The susceptible interaction ('Vernal'–Pmm) was characterized by rapid disruption of host mitochondria in cells adjacent to intercellular hyphae, dissolution of host cell walls, and death of host cells 12–24 h after inoculation. Colonization of roots was extensive, and hyphae usually appeared healthy. Both host resistant (M193–Pmm) and nonhost resistant (M193 or 'Vernal' – Pmg) interactions were characterized by hyphal growth inhibition, production of cell wall appositions in root cells in contact with hyphae, and rapid necrosis of root cells. Wall appositions were more numerous in root cells in contact with Pmg than with Pmm, and rapid cell necrosis was more extensive in the nonhost resistant interaction than in the host resistant interaction. Numerous abnormalities were observed in Pmg hyphae. Nonhost resistance was expressed more rapidly and appeared to be more effective than host resistance in limiting hyphal growth. An examination of a compatible interaction of Pmg with soybean indicated that its mode of pathogenesis may be fundamentally different from that of Pmm in alfalfa.

Light microscope observations of susceptible, host resistant, and nonhost resistant interactions of alfalfa with Phytophthora megasperma

1984 ◽  
Vol 62 (1) ◽  
pp. 109-116 ◽  
Author(s):  
Sally A. Miller ◽  
Douglas P. Maxwell
Keyword(s):  
Glycine Max ◽  
Light Microscopy ◽  
Host Resistance ◽  
Light Microscope ◽  
Nonhost Resistance ◽  
Root Cells ◽  
Phytophthora Megasperma ◽  
Susceptible Host ◽  
Glycine Max L ◽  
Medicago Sativa L

Susceptibility and host resistance in alfalfa (Medicago sativa L.) to Phytophthora megasperma Drechs. f. sp. medicaginis (Pmm), an alfalfa pathogen, and nonhost resistance to P. megasperma f. sp. glycinea (Pmg), a pathogen of soybean (Glycine max (L.) Merr.) but not alfalfa, were compared by light microscopy. Zoospores of Pmm and Pmg were attracted to and became encysted upon roots of Pmm-resistant and Pmm-susceptible alfalfa seedlings within 60 min after inoculation. Cysts germinated and grew toward the roots, and penetration was usually intercellular. The extent of colonization by Pmm and Pmg was similar in all cases at 2 h after inoculation, but at 12 and 24 h colonization was much more extensive in the susceptible interaction than in the host resistant or nonhost resistant interactions. In both the host resistant and nonhost resistant interactions, root cells in contact with hyphae were plasmolyzed and (or) necrotic. Although numerous similarities exist between host resistance to Pmm and nonhost resistance to Pmg in alfalfa seedlings, nonhost resistance is apparently triggered more rapidly and (or) is more effective than host resistance in this system.

Etude ultrastructurale des relations hôte–parasite au cours de l'infection des pommes par le Phytophthora cactorum

1981 ◽  
Vol 59 (2) ◽  
pp. 251-263 ◽  
Author(s):  
X. Mourichon ◽  
G. Sallé
Keyword(s):  
Cell Walls ◽  
Susceptible Variety ◽  
Host Cells ◽  
Phytophthora Cactorum ◽  
Electron Microscopic ◽  
Susceptible Host ◽  
Golden Delicious ◽  
Extrahaustorial Matrix ◽  
Apple Fruits

An electron microscopic study was performed on haustoria of Phytophthora cactorum (L. et C.) Schroeter developed in tissues of two cultivars of apple fruits: a susceptible variety ('Golden delicious') and a resistant one ('Belle de Boskoop'). Ultrastructure of intercellular hyphae and some aspects of their penetration between contiguous host cells were described. A light dissolution of the host cell walls was observed. Ontogenic investigations indicated that in the susceptible host, the wall of the fungal haustoria was covered with a dense-stained extrahaustorial matrix. Its origin and its polysaccharide nature were demonstrated. On the other hand, the resistant host developed, immediately after the inoculation, a papilla which gave rise, later on, to a sheath enclosing adult haustoria. The role of these callosic structures in the phenomenon of resistance was discussed.

scholarly journals A novel putative microtubule-associated protein is involved in arbuscule development during arbuscular mycorrhiza formation

2021 ◽  
Author(s):  
Tania Ho-Plágaro ◽  
Raúl Huertas ◽  
María I Tamayo-Navarrete ◽  
Elison Blancaflor ◽  
Nuria Gavara ◽  
...  
Keyword(s):  
Plant Root ◽  
Arbuscular Mycorrhizal ◽  
Host Cells ◽  
Root Cells ◽  
Filament Dynamics ◽  
Fungal Structure ◽  
Genes Encoding ◽  
Associated Proteins ◽  
Mycorrhizal Development

Abstract The formation of arbuscular mycorrhizal (AM) symbiosis requires plant root host cells to undergo major structural and functional reprogramming in order to house the highly branched AM fungal structure for the reciprocal exchange of nutrients. These morphological modifications are associated with cytoskeleton remodelling. However, molecular bases and the role of microtubules (MTs) and actin filament dynamics during AM formation are largely unknown. In this study, the tomato tsb gene, belonging to a Solanaceae group of genes encoding MT-associated proteins for pollen development, was found to be highly expressed in root cells containing arbuscules. At earlier stages of mycorrhizal development, tsb overexpression enhanced the formation of highly developed and transcriptionally active arbuscules, while tsb silencing hampers the formation of mature arbuscules and represses arbuscule functionality. However, at later stages of mycorrhizal colonization, tsb OE roots accumulate fully developed transcriptionally inactive arbuscules, suggesting that the collapse and turnover of arbuscules might be impaired by TSB accumulation. Imaging analysis of the MT cytoskeleton in cortex root cells overexpressing tsb revealed that TSB is involved in MT-bundling. Taken together, our results provide unprecedented insights into the role of novel MT-associated protein in MT rearrangements throughout the different stages of the arbuscule life cycle.

scholarly journals FlsnRNA-seq: protoplasting-free full-length single-nucleus RNA profiling in plants

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Yanping Long ◽  
Zhijian Liu ◽  
Jinbu Jia ◽  
Weipeng Mo ◽  
Liang Fang ◽  
...  
Keyword(s):  
Single Cell ◽  
Cell Walls ◽  
Large Scale ◽  
Full Length ◽  
Cell Level ◽  
Root Cells ◽  
Rna Profiling ◽  
Different Types ◽  
Long Read ◽  
Single Nucleus

AbstractThe broad application of single-cell RNA profiling in plants has been hindered by the prerequisite of protoplasting that requires digesting the cell walls from different types of plant tissues. Here, we present a protoplasting-free approach, flsnRNA-seq, for large-scale full-length RNA profiling at a single-nucleus level in plants using isolated nuclei. Combined with 10x Genomics and Nanopore long-read sequencing, we validate the robustness of this approach in Arabidopsis root cells and the developing endosperm. Sequencing results demonstrate that it allows for uncovering alternative splicing and polyadenylation-related RNA isoform information at the single-cell level, which facilitates characterizing cell identities.

Penetration and growth of compatible and incompatible races of Phytophthora megasperma var. sojae in soybean hypocotyl tissues differing in age

1980 ◽  
Vol 58 (24) ◽  
pp. 2594-2601 ◽  
Author(s):  
P. Stössel ◽  
G. Lazarovits ◽  
E. W. B. Ward
Keyword(s):  
Glycine Max ◽  
Epidermal Cells ◽  
Mechanisms Of Resistance ◽  
Hypocotyl Growth ◽  
Phytophthora Megasperma ◽  
Cell Layers ◽  
Glycine Max L ◽  
Incompatible Reaction ◽  
Race 4 ◽  
Incompatible Interactions

Intact 6-day old soybean hypocotyls (Glycine max L., cv. Altona) were inoculated with zoospores of Phytophthora megasperma Drechs. var. sojae Hildeb. either at the top (susceptible to compatible races, resistant to incompatible races) or the bottom (resistant to both compatible and incompatible races) and, after a 22-h incubation, were examined by light microscopy. Penetration at the top and bottom by both compatible (race 6) and incompatible (race 4) P. megasperma var. sojae was predominantly between anticlinal walls of epidermal cells. Both races, but especially race 4, also penetrated directly into the outer walls of epidermal cells, but epidermal cells rarely were invaded. Both races grew mainly intercellularly, but race 6 produced haustoria more frequently than race 4. Race 6 haustoria at the top of the hypocotyl were usually encased, those of race 4 were not. Growth of both races was equally dense in the first few cell layers, but the numbers of race 4 hyphae decreased rapidly while those of race 6 became more abundant in the deeper layers. With race 4, but not with race 6, most cells in the infected tissue were necrotic. Differences between the compatible and the incompatible interactions were not absolute; there were many unsuccessful invasion attempts by race 6 and individual hyphae of race 4 spread deeply into the tissue. At the bottom of the hypocotyl, growth of both races was more restricted. Race 6 produced fewer haustoria than at the top, and similarities to the incompatible reaction with race 4 at the top suggest that similar mechanisms of resistance may be involved.

scholarly journals Exposure of ichnovirus particles to digitonin leads to enhanced infectivity and induces fusion from without in an in vitro model system

2007 ◽  
Vol 88 (11) ◽  
pp. 2977-2984 ◽  
Author(s):  
Don Stoltz ◽  
Renée Lapointe ◽  
Andrea Makkay ◽  
Michel Cusson
Keyword(s):  
Outer Membrane ◽  
In Vitro Model ◽  
Model System ◽  
Host Cells ◽  
Fusion Event ◽  
Susceptible Host ◽  
In Vitro Model System ◽  
Vitro Model

Unlike most viruses, the mature ichnovirus particle possesses two unit membrane envelopes. Following loss of the outer membrane in vivo, nucleocapsids are believed to gain entry into the cytosol via a membrane fusion event involving the inner membrane and the plasma membrane of susceptible host cells; accordingly, experimentally induced damage to the outer membrane might be expected to increase infectivity. Here, in an attempt to develop an in vitro model system for studying ichnovirus infection, we show that digitonin-induced disruption of the virion outer membrane not only increases infectivity, but also uncovers an activity not previously associated with any polydnavirus: fusion from without.

Glycine max (L.) Merr., Vigna radiata L. and Medicago sativa L. sprouts: A natural source of bioactive compounds

2013 ◽  
Vol 50 (1) ◽  
pp. 167-175 ◽  
Author(s):  
Luís R. Silva ◽  
Maria J. Pereira ◽  
Jessica Azevedo ◽  
Rui F. Gonçalves ◽  
Patrícia Valentão ◽  
...  
Keyword(s):  
Glycine Max ◽  
Medicago Sativa ◽  
Bioactive Compounds ◽  
Vigna Radiata ◽  
Natural Source ◽  
Glycine Max L ◽  
Medicago Sativa L

Caractérisation ultrastructurale d'une résistance induite par un éliciteur d'origine fongique, chez un cultivar sensible de Piment

1990 ◽  
Vol 68 (2) ◽  
pp. 381-390 ◽  
Author(s):  
C. Coulomb ◽  
P. J. Coulomb ◽  
I. Saimmaime ◽  
Y. Lizzi ◽  
C. Polian
Keyword(s):  
Endoplasmic Reticulum ◽  
Capsicum Annuum ◽  
Defense Response ◽  
Culture Medium ◽  
Phytophthora Capsici ◽  
Physiological State ◽  
Sweet Pepper ◽  
Host Cells ◽  
Lytic Function ◽  
Wall Appositions

Elicitation of a sensitive sweet pepper (Capsicum annuum) cultivar roots by immersion in the culture medium of Trichoderma album induces resistance in leaves infected by Phytophthora capsici. In infected tissues, host cells are intact and develop wall formations that look like typical wall appositions, but differ from them by the presence of a substance of cytoplasmic origin, which is phagocytized and degraded, conferring a lytic function and unusual dynamics to these structures. The involvement of the endoplasmic reticulum and peroxysomes in eventual detoxification processes is discussed. The resistance induced by this elicitor seems to be programmed by the establishment of a reactive physiological state, which produces the defense response.

scholarly journals Electron microscopic studies on the interaction between Lactobacillus phage PL-1 and cell walls isolated from its host cells.

1980 ◽  
Vol 26 (6) ◽  
pp. 413-420 ◽  
Author(s):  
KENJI WATANABE ◽  
SHIGESHI TAKESUE ◽  
KAZUKO ISHIBASHI
Keyword(s):  
Cell Walls ◽  
Host Cells ◽  
Electron Microscopic ◽  
Microscopic Studies

AC Caribou alfalfa

1992 ◽  
Vol 72 (3) ◽  
pp. 845-847
Author(s):  
R. Michaud ◽  
C. Richard
Keyword(s):  
Medicago Sativa ◽  
Research Station ◽  
Clavibacter Michiganensis ◽  
Maritime Provinces ◽  
Phytophthora Megasperma ◽  
Phytophthora Root Rot ◽  
Clavibacter Michiganensis Subsp ◽  
Cultivar Description ◽  
Medicago Sativa L ◽  
Moderately Resistant

AC Caribou alfalfa (Medicago sativa L.) is a cultivar developed by the Agriculture Canada Research Station in Sainte-Foy. It is similar to Iroquois in maturity, rate of growth, and fall dormancy. It is highly resistant to bacterial wilt (caused by Clavibacter michiganensis subsp. insidiosus (McCulloch) Davis, Gillaspie, Vidaver & Harris), resistant to verticillium wilt (caused by Verticillium albo-atrum Reinke & Berth.), and moderately resistant to phytophthora root rot (caused by Phytophthora megasperma Dreschs. f. sp. medicaginis T. Kuan & D. C. Erwin). AC Caribou, an alfalfa with fine leafy stems, is well suited for production in Quebec and the Maritime Provinces where winter survival may be a problem.Key words: Alfalfa, Medicago sativa, cultivar description

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