Reassessment of the role of phospholipids in sexual reproduction by sterol-auxotrophic fungi

Kerwin, James L.; Duddles, N D

doi:10.1128/jb.171.7.3831-3839.1989

Cited by 30 publications

(22 citation statements)

References 59 publications

(63 reference statements)

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“…When the putative sterols in 100 mg lecithin were isolated by column chromatography, and purified by digitonin precipitation, GC-MS analysis of the digitonide component failed to detect any sterols. The amount of putative sterols in the digitonide component of cephalin was also too small to be analysed by GC-MS. Kerwin & Duddles (1989) reported the detection of 631 and 587 ng cholesterol in two separate 1 g samples of 99 Yo synthetic dioleoyl phosphatidylcholine using GC-MS analysis. Based on their data, 100 pg phospholipids per basal medium disc used in this study should contain about 0-06 ng cholesterol.…”

Section: Discussionmentioning

confidence: 99%

“…During the initial phase of this study, it was found that certain commercial samples of lecithins were stimulatory to oospore formation only after washing with deionized water. It is therefore suggested that the decrease of oosporogenesis reported in the literature (Kerwin & Duddles, 1989;Nes, 1988) could be due to the presence of inhibitory substances.…”

Section: Introductionmentioning

confidence: 99%

“…After incubation at 24 "C for 14 d, a culture strip of the same size was obtained 20 mm from the inoculum and placed in the centre of a plate containing fresh basal medium. The procedure was repeated at least 10 times before use to avoid possible sterol contamination in the original inoculum from V-8 agar culture (Kerwin & Duddles, 1989). Under such conditions, a single isolate of P .…”

Section: Methodsmentioning

confidence: 99%

“…Assuming that the 1 % impurity in the natural lecithin used is all sterols, it has been estimated that such sterol impurity would account for less than 2% of oospores produced in the presence of lecithin (KO, 1985). Kerwin & Duddles (1989) and Nes (1988) found that the ability of lecithin to induce oospore formation in P. cactorum diminished after passage through aminopropyl or alumina columns, respectively, and assumed that such an effect was due to removal of sterol contaminants. During the initial phase of this study, it was found that certain commercial samples of lecithins were stimulatory to oospore formation only after washing with deionized water.…”

Section: Introductionmentioning

confidence: 99%

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Stimulation of sexual reproduction in Phytophthora cactorum by phospholipids is not due to sterol contamination

Jee

Tang

1997

Microbiology

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Phytophthora cadorum did not form oospores on basal medium unless phosphatidylcholine (lecithin) or phosphatidylethanolamine (cephalin) was added. After removal of putative sterols by aminopropyl column chromatography, the activities of lecithin and cephalin were increased 47-and 2*8-fold, respectively, thus confirming the previous reports that sterols are not essential for sexual reproduction in this organism. Thin-layer chromatography (TLC) of the commercial lecithin revealed the presence of an unknown inhibitory substance which, when added to the purified lecithin, caused a 50% reduction of oospore formation. Commercial cephalin also showed a twofold increase in activity after removal of putative sterols and the existence of an unknown inhibitor when it was subjected to TLC. Addition of the inhibitor to the purified cephalin completely inhibited the growth of the test organism. One sample of lecithin tested was not stimulatory to oospore formation. However, after washing with deionized water or NaCl solution, it induced the production of 17300 and 24450 oospores (100 pg)-', respectively. The ability of cephalin to induce oospore formation was increased 2.3-fold by washing with deionized water and 8-3-fold by washing with NaCl solution. Like sterols, the digitonin precipitable component (digitonide) of the non-phospholipid fraction of commercial lecithin or cephalin was stimulatory to oospore formation of P. cactorum but not Phytophthora parasitica. However, the non-digitonide component was not only more active than the digitonide component, but also stimulatory to P. parasitica. Gas chromatography and mass spectrometry (GC-MS) analysis of the digitonide component from lecithin failed to detect any putative sterol contaminant. The amount of the putative sterol contaminant in the digitonide component from cephalin was also below the detection limit of GC-MS. When 001-10 ng cholesterol was added to basal medium discs each containing 100 pg cephalin, the numbers of oospores produced by P. cactorum and P. parasitica were not significantly changed. It is concluded that, in the fungi tested, sterols did not play any significant role in the stimulation of sexual reproduction by highly purified phospholipids.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Stimulation of sexual reproduction in Phytophthora cactorum by phospholipids is not due to sterol contamination

Jee

Tang

1997

Microbiology

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“…But a lack of sterol supply does not prevent the fungal growth of P. cactorum. Stimulation of reproduction-organ formation could be obtained by bringing phospholipids to P. cactorum [66,67] or to Pythium aphanidermatum [68], even with synthetic compounds, which avoids traces of sterol contaminations as was proposed to explain phospholipids activity [69]. It was also reported that unsaturated fatty acids as well as their triglycerides are good inducers of reproduction in P. cinnamomi [70] and in both P. cactorum and P. parasitica [71].…”

Section: Sterols In Oomycete Physiologymentioning

confidence: 99%

Involvement of lipid-protein complexes in plant-microorganism interactions

Blein¹

2002

OCL

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Summary : Increasing concerns about the environmental impact of modern agricultural have prompted research for alternate practices to pesticide treatments, notably using plant defense mechanisms. Thus, isolation and characterization of plant defense elicitors have been the main step of studies in many groups. Moreover, in the global concept of interactions between organisms and their environment, a major concern is to discriminate recognition between exogenous and endogenous signals, notably during pathogenic or allergenic interactions involving small proteins, such as elicitins or lipid transfer proteins (LTPs). Elicitins and lipid transfer proteins (LTP) are both able to load and transfer lipidic molecules and share some structural and functional properties. While elicitins are known as elicitors of plant defense mechanisms, the biological function of LTPs is still an enigma. They are ubiquitous plant proteins able to load and transfer hydrophobic molecules such as fatty acids or phospholipids. Among them, LTPs1 (type 1 lipid transfer proteins) constitute a multigenic family of secreted plant lipid binding proteins that are constitutively expressed in specific tissues and/or induced in response to biotic and abiotic stress (for reviews [1][2][3][4]). Their biological function is still unknown, even if some data provide arguments for a role of these proteins in the assembly of extracellular hydrophobic polymers (i.e., cutin and suberin) [2,4] and/or in plant defense against fungal pathogens [1,3]. Beside their involvement in plant defense, LTPs1 are also known to be pan-allergens of plant-derived foods [5]. Finally, the discovery of the sterol carrier-properties of elicitins has opened new perspectives dealing with the relationship between this function and the elicitor activity of these small cystein-rich proteins. Nevertheless, this elicitor activity is restrained to few plant species, and thus does not appear in accordance with a universal lipid transfer function. These considerations required a reassessment of the precise role of elicitins for both fungi and plants [6].Résumé : La stimulation des mécanismes naturels de défense des plantes représente une stratégie alternative à l'utilisation de la lutte chimique en phytoprotection. Dans ce contexte, les élicitines, qui sont de petites protéines sécrétées par des Phytophthora et des Pythium, induisent une réaction de type hypersensible chez des plantes comme le tabac. Ces plantes deviennent résistantes à l'agression de leurs agents pathogènes. La récente découverte que les élicitines sont des protéines de transfert de stérols a apporté une vue nouvelle sur l'activité moléculaire des élicitines. Élicitines et protéines de transfert de lipides (LTP) sont capables de charger et de transporter des molécules lipidiques et partagent des caractères communs tant au plan structural que fonctionnel mais, tandis que les élicitines sont connues pour leur activité élicitrice de réaction de défense chez les plantes, l'activité biologique des LTP reste inconnue. Cependant, ...

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Oomycete Genetics and Genomics

Lamour¹,

Kamoun²

2008

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Reassessment of the role of phospholipids in sexual reproduction by sterol-auxotrophic fungi

Cited by 30 publications

References 59 publications

Stimulation of sexual reproduction in Phytophthora cactorum by phospholipids is not due to sterol contamination

Stimulation of sexual reproduction in Phytophthora cactorum by phospholipids is not due to sterol contamination

Involvement of lipid-protein complexes in plant-microorganism interactions

Oomycete Genetics and Genomics

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