Encystment of zoospores of the fungus,Phytophthora cinnamomi, is induced by specific lectin and monoclonal antibody binding to the cell surface

Hardham, Adrienne R.; Suzaki, Etsuko

doi:10.1007/bf01304632

Cited by 67 publications

(17 citation statements)

References 22 publications

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“…If new receptors are added in this way, tben cytological changes during the preinfection sequence (Hardbam, 1992) could have additional relevance m ensuring a temporal separation of receptor functions. There is no direct evidence of this, but it would be compatible with the findings here and with some of the changes in cell surface components detectable by monoclonal antibody probes (Hardham & Suzaki, 1986;P.stradaCiarcia et al, 1989). Receptors could also be spatially separated, as in tbe case of tropic receptors at the germ-tube tip.…”

Section: D1 S C R S S I O Xsupporting

confidence: 81%

“…They suggest, instead, that the responses were mediated by receptors, compatible with receptor-mediated taxis m many other organisms (Armitage & Lackie, 1990) and with the induction of encystmenl by specific monoclonal antibodies 111 both Pythium and Phytophthora spp. (Hardham & Suzaki, 1986;Estrada-Garcia et al, 1990). Competition experiments (1 able 2) supported this view.…”

Section: D1 S C R S S I O Xmentioning

confidence: 75%

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Effects of amino acids and sugars on zoospore taxis, encystment and cyst germination in Pythium aphanidermatum (Edson) Fitzp., P. catenulatum Matthews and P. dissotocum Drechs.

Donaldson

Deacon

1993

New Phytologist

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SUMMARY Nineteen L‐amino acids, the corresponding D‐amino acids and 10 sugars were tested as elicitors of zoospore taxis, encystment and cyst germination in Pythium aphanidermatum (Edson) Fitzp., P. catenulatum Matthews and P. dissotocum Drechs. Selected compounds were also tested for promotion of germ‐tube growth and competition in zoospore taxis. Each fungus responded to a different spectrum of compounds at different stages of development; for example, in P. aphanidermatum L‐glutamine elicited taxis but not germination, whereas glucose elicited germination but not taxis. At each stage of development the fungi showed common responses to some compounds but different responses to others. For example, all fungi showed positive taxis to L‐aspartic acid, L‐asparagine, L‐glutamic acid, L‐glutamine and L‐alanine, but differed in taxis to sugars. Nevertheless, all three fungi responded to the same broad range of compounds at one stage or another. The compounds that elicited germination did not always promote growth, and D‐amino acids had no effect at any stage, indicating that taxis, encystment and germination were receptor‐mediated. However, some non‐attractant amino acids interfered with chemotaxis, to different degrees in the three fungi. The findings are discussed in relation to host‐location mechanisms, including host‐differential taxis to roots. Variations in chemoresponses of Pythium are suggested to involve receptors for a common range of compounds, differentially active at different stages of the pre‐infection sequence.

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Section: D1 S C R S S I O Xsupporting

confidence: 81%

Section: D1 S C R S S I O Xmentioning

confidence: 75%

Effects of amino acids and sugars on zoospore taxis, encystment and cyst germination in Pythium aphanidermatum (Edson) Fitzp., P. catenulatum Matthews and P. dissotocum Drechs.

Donaldson

Deacon

1993

New Phytologist

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“…To obtain zoospores, the methodology of Hardham & Suzaki (1986) was modified slightly. Hyphal plugs were cut from stock cultures and placed onto a sterilized nappy liner (that had been boiled three times) overlying PYG media.…”

Section: Methodsmentioning

confidence: 99%

A pressure gradient facilitates mass flow in the oomycete Achlya bisexualis

Muralidhar

Swadel

Spiekerman³

et al. 2016

Microbiology

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We have used a single cell pressure probe and observed movement of microinjected oil droplets to investigate mass flow in the oomycete Achlya bisexualis. To facilitate these experiments, split Petri dishes that had media containing different sorbitol concentrations (and hence a different osmotic potential) on each side of the dish were inoculated with a single zoospore. An initial germ tube grew out from this and formed a mycelium that extended over both sides of the Petri dish. Hyphae growing on the 0 M sorbitol side of the dish had a mean turgor (¡SEM) of 0.53¡0.03 MPa (n513) and on the 0.3 M sorbitol side had a mean turgor (¡SEM) of 0.3¡0.027 MPa (n59). Oil droplets that had been microinjected into the hyphae moved towards the lower turgor area of the mycelia (i.e. retrograde movement when microinjected into hyphae on the 0 M sorbitol side of the split Petri dish and anterograde movement when microinjected into hyphae on the 0.3 M sorbitol side of the Petri dish). In contrast, the movement of small refractile vesicles occurred in both directions irrespective of the pressure gradient. Experiments with neutral red indicate that the dye is able to move through the mycelia from one side of a split Petri dish to the other, suggesting that there is no compartmentation. This study shows that hyphae that are part of the same mycelia can have different turgor pressures and that this pressure gradient can drive mass flow.

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“…But the orientation of encystment by Pythium and Phytophthora strongly suggests that the fiagella are involved in the recognition event. Support for this has come from the use of monoclonal antibodies raised against P. cinnamomi (Hardham & Suzaki, 1986). Seven types of MAb were identified, with different patterns of binding specificity.…”

Section: Zoospore Docking and Encystmentmentioning

confidence: 99%

Ecological implications of recognition events in the pre‐infection stages of root pathogens

Deacon

1996

New Phytologist

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SUMMARYHost-specificity and recognition by root-infecting pathogens are reviewed, with emphasis on fungi but drawing parallels with other root parasites, synnbionts and rhizosphere micro-organisms. Two major levels of specificity are identified; family-specific parasitism, exemplified by many parasites that characteristically infect Gramineae, and the possibly recent segregation of pathogen species into crop-specific strains. In both of these cases there are examples w^here host-specificity is paralleled by host-recognition in the pre-infection stages, including hostspecific triggering of propagule germination. The pre-infection sequence of zoosporic pathogens (Pythium, Phyiophthora, Aphanomyces spp.) is reviewed. These fungi seem to have both general (low-affinity) and hostspecific (high-affinity) receptor-based recognition systems for chemotaxis to root difFusates and for induction of encystment by host surface coniponents, Zoospores orientate (dock) during encystment, and the cysts germinate from a fixed point, whereas the non-motiie spores of at least some root parasites (e.g. Idriella bolleyi) can germinate from any point, which is infiuenced by the host.The possession of both general and host-specific recognition systems by a parasite could enable it to exploit rhizosphere niches or to invade compromised plants in the absence of preferred hosts. Evidence from graminicolous (family-specific) Pythium spp. suggests that host-specific recognition is quantitative rather than absolute but, when compounded over successive cycles of infection, is a powerful selective mechanisna.

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Encystment of zoospores of the fungus,Phytophthora cinnamomi, is induced by specific lectin and monoclonal antibody binding to the cell surface

Cited by 67 publications

References 22 publications

Effects of amino acids and sugars on zoospore taxis, encystment and cyst germination in Pythium aphanidermatum (Edson) Fitzp., P. catenulatum Matthews and P. dissotocum Drechs.

Effects of amino acids and sugars on zoospore taxis, encystment and cyst germination in Pythium aphanidermatum (Edson) Fitzp., P. catenulatum Matthews and P. dissotocum Drechs.

A pressure gradient facilitates mass flow in the oomycete Achlya bisexualis

Ecological implications of recognition events in the pre‐infection stages of root pathogens

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