The Sterol Requirement of Phytophthora Cactorum

Elliott, C. G.; Hendrie, Margaret R.; Knights, B.A.

doi:10.1099/00221287-42-3-425

Cited by 78 publications

(34 citation statements)

References 7 publications

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“…Isolates were grown in 20 ml still culture of a sucrose/asparagine/mineral salts broth containing 30 g ml Ϫ1 ␤-sitosterol (Elliott et al, 1966) at SCRI and unclarified V8 medium at CRCTPP. After vacuum filtration, the mycelium was freeze-dried for extended storage at Ϫ20°C.…”

Section: Methodsmentioning

confidence: 99%

A Molecular Phylogeny of Phytophthora and Related Oomycetes

Cooke¹,

Drenth

Duncan³

et al. 2000

Fungal Genetics and Biology

975

775

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Section: Methodsmentioning

confidence: 99%

A Molecular Phylogeny of Phytophthora and Related Oomycetes

Cooke¹,

Drenth

Duncan³

et al. 2000

Fungal Genetics and Biology

975

775

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“…e., oospores capable of germination. Although P. cactorum displays an enzymic preference to metabolize certain nuclear B-ring unsaturated (16), but not saturated (17), sterols to A5 sterols and a strict sterol requirement for oospore production (18,19), the selectivity for sterols in terms of initial uptake (20), accumulation into logarithmic-phase cultures (17), and derivatization to esters (13,21) and glycosides (13,21), and their effects on growth response (17,22) and induction of sexual structures (23,24) is less obvious. Nevertheless, the different physiological and biochemical recognitions of sterols exhibited by P. cactorum imply a multiplicity of roles that become operational at different times during the life cycle.…”

mentioning

confidence: 99%

Evidence for metabolic and functional discrimination of sterols by Phytophthora cactorum

Nes

Stafford

1983

Proc. Natl. Acad. Sci. U.S.A.

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When fed 10 ppm of one of the following sterols: cholesterol (cholest-5-en-3l-ol), wingsterol (21-isopentylcholesterol), desmosterol [cholesta-5,24(25)-dien-3l-ol], 24-methylenecholesterol [ergosta-5,24(28)-dien-3,-ol], or fucosterol [stigmasta-5,24(28)-dien-3.&ol], the pathogenic fungus Phytophthora cactorum, which is naturally unable to epoxidize squalene, accumulated each of the test compounds to similar levels. Fucosterol, the only sterol metabolized, was reduced to yield 24-ethylcholesterol. All the sterols tested induced the formation of sex structures. Fertilization and subsequent maturation of oospores capable of germination occurred only with the naturally occurring sterols. Wingsterol treatments resulted in aborted oospores. None of the sterols tested was inhibitory to growth, measured as changes in the 21-day mycelial dry weight. The results are consistent with the view that the accumulated sterol functions to regulate the life cycle of P. cactorum. However, the metabolism and kinds of recognition of the sterol molecule, in terms of uptake and effects on growth and induction of the various sexual events, contrast sharply with what is known for other oomycetous fungi such as Achlya and Saprolegnia. This implies that the evolutionary histories of the Oomycetes may be different.The occurrence, biosynthesis, and metabolism of sterols has been studied in numerous oomycetous fungi [orders Saprolegniales (1-3), Leptomitales (1), Lagenidiales (4), and Peronosporales (5-10)]. The physiological roles of sterols and other polycyclic isopentenoids in effecting growth and reproduction have also been the subject of much investigation (11)(12)(13)(14).Phytophthora cactorum (order Peronosporales, family Pythiaceae) is a soil-borne pathogen of higher plants-e.g., fruit trees (15)-which, unlike many of the other oomycetous fungi, lacks sterol synthetic capabilities (6)(7)(8)(9)(10). This deficiency has resulted in a heterotrophic requirement for naturally occurring host sterols to stimulate vegetative growth and an auxotrophic requirement for these sterols to produce functional oospores-i. e., oospores capable of germination. Although P. cactorum displays an enzymic preference to metabolize certain nuclear B-ring unsaturated (16), but not saturated (17), sterols to A5 sterols and a strict sterol requirement for oospore production (18,19), the selectivity for sterols in terms of initial uptake (20), accumulation into logarithmic-phase cultures (17), and derivatization to esters (13, 21) and glycosides (13,21), and their effects on growth response (17,22) (HPLC) and other uses were purchased from MCB Labs. TLC plates were from Analtech (adsorption TLC) and Whatman (reversed-phase TLC). Aluminum oxide (neutral) was from ICN.Culture and Growth Conditions. P. cactorum, strain 51-22, was provided by R. Berman (University of California, Berkeley). The fungus was maintained on supplemented agar plates (27, 28) or cultured on a nonbuffered, liquid (sterol-free) synthetic medium (17). Four types of experimental cultu...

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“…Demel, Bruckdorfer & Van Deenen, 1g72a, b) and erythrocytes (Bruckdorfer et al, 1969)~ and by their effect in promoting growth of mycoplasma (Smith & Lynn, 1958;Smith, 1964;Rottem, Pfendt & Hayflick, 1971). There is no significant difference in the growth rate of P. cactorum grown with the two sterols, measured either as colony diameter or as weight of mycelium (Elliott et al, 1966;Elliott, 1968). It is conceivable that the oosphere membrane might have special properties which are defective when it contains cholestanol rather than cholesterol, but in that case one would hardly expect degeneration to occur at the beginning of meiosis, before oosphere delimitation.…”

Section: Discussionmentioning

confidence: 87%

“…Phytophthora cactorum was grown at 25 "C in IOO ml conical flasks containing 10 ml liquid basal medium (Elliott, Hendrie & Knights, 1966) plus CaCl, (0.1 g 1-l). Four days after inoculation of the sterol-free medium, IOO p g cholesterol or cholestanol, dissolved in I ml of I % (v/v) aqueous solution of Tween 80, was added to each flask.…”

Section: Methodsmentioning

confidence: 99%