Sterols in Growth and Reproduction of Fungi

Hendrix, James W.

doi:10.1146/annurev.py.08.090170.000551

Cited by 174 publications

(83 citation statements)

References 58 publications

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“…Endophytic fungi can indirectly affect insect herbivores by altering plant nutritional chemistry and morphological traits (Duffey and Felton 1991;Bernays 1993), through the production of alkoloid-based defensive compounds in the plant tissues (Clay and Holah 1999), or through competition between the fungus and the herbivore for a resource supplied by their shared host plant essential for both organisms (Hendrix 1970). In our system, phytosterols (Dugassa-Gobena et al 1998) and volatile profiles (this study) are the only plant metabolites known so far to be altered quantitatively as well as in proportional compositions in inoculated plants.…”

Section: Fig 3 Mean Percentages (±Sd) Of Number Of Times Tetheredmentioning

confidence: 99%

Influence of an endophytic fungus on host plant selection by a polyphagous moth via volatile spectrum changes

Jallow

Dugassa‐Gobena

Vidal

2008

Arthropod-Plant Interactions

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Recently the role of micro-organisms as mediators of plant-herbivore interactions has been increasingly acknowledged in ecological research. We investigated the interaction between an unspecialized root fungal endophyte (Acremonium strictum) and the polyphagous moth Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), in greenhouse and laboratory bioassays. Specifically we examined in tomato (Lycopersicon esculentum Mill.) the systemic effects of the endophytic fungus on the host selection behaviour of female moths for oviposition and the volatile profiles of host plants to understand the mechanisms acting in this multi-trophic model system. Both laboratory and field strains of H. armigera moths oviposited more on leaves of A. strictum inoculated plants as compared to endophyte-free plants, both in free flight cages and in tethered moth laboratory experiments; the moth's preferences were significant between 10 and 18 days after inoculation. The analysis of volatile profiles showed strong quantitative differences between treatments. Endophyte inoculated plants emitted diverse terpenes and sesquiterpenes at significantly lower amounts as compared to endophyte free-plants, except for a-terpinene, which did not differ between the treatments, and trans-bcaryophyllene, which was emitted in significantly higher amounts on inoculated plants. b-Thujene and a-phellandrene accounted for 73.3 and 12.0% of total amounts of volatiles emitted from endophyte-free and inoculated plants, respectively. Our findings demonstrate that A. strictum is able to systemically influence the host selection of H. armigera moths for oviposition; conceivably mediated by the induced changes in volatile emissions (and probably additional biochemical parameters of the host plants, which have not been analysed so far). We argue for a more detailed assessment of micro-organisms invisibly colonizing plants, when studying plant-herbivore or multitrophic interactions.

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Section: Fig 3 Mean Percentages (±Sd) Of Number Of Times Tetheredmentioning

confidence: 99%

Influence of an endophytic fungus on host plant selection by a polyphagous moth via volatile spectrum changes

Jallow

Dugassa‐Gobena

Vidal

2008

Arthropod-Plant Interactions

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“…For over two decades it has been accepted that sterolauxotrophic fungi of the Pythiaceae (Oomycetes) require an exogenous source of these compounds for sexual reproduction (14,15,(19)(20)(21). Requirements for sterols have also been documented for asexual (11) and sexual (30) reproduction by the facultative mosquito parasite Lagenidiim ,ngiganteuim (Oomycetes:Lagenidiales), which cannot synthesize these compounds (60).…”

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confidence: 99%

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

Kerwin

Duddles

1989

J Bacteriol

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Several genera of oomycete fungi which are incapable of de novo sterol synthesis do not require these compounds for vegetative growth. The requirement for an exogenous source of sterols for sexual reproduction by several members of the Pythiaceae has been questioned by reports of apparent induction and maturation of oospores on defined media supplemented with phospholipids in the absence of sterols. A more detailed examination of this phenomenon suggested that trace levels of sterols in the inoculum of some pythiaceous fungi act synergistically with phospholipid medium supplements containing unsaturated fatty acid moieties to induce oosporogenesis. Phospholipid analysis of one species, Pythium ultimum, suggested that only the fatty acid portion of the exogenous phospholipid is taken up by the fungus. Enrichment of the phospholipid fraction of total cell lipid of P. ultimum with unsaturated fatty acids promoted oospore induction, and enhanced levels of unsaturated fatty acids in the neutral lipid fraction increased oospore viability. For some pythiaceous fungi, the levels of sterols required for the maturation of oospores with appropriate phospholipid medium supplementation suggest that these compounds are necessary only for the sparking and critical domain roles previously described in other fungi.

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“…1983 ; Hendrix, 1970). However, it was subsequently found that sterols are stimulatory but not essential to Since 1964, a number of pythiaceous fungi have been sexual reproduction in Phytophthora cactorum (Lebert reported to have a sterol requirement for sexual re-& Cohn) Schroeter because such a stimulatory effect can production because of their inability to form oospores be replaced by phosphatidylcholines (lecithins) from on basal medium unless sterols were added (Elliott, various sources (KO, 1985;KO & Ho, 1983) and by soybean phosphatidylethanolamine (cephalin) (KO, KO & Ho, 1983).…”

Section: Introductionmentioning

confidence: 99%

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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Sterols in Growth and Reproduction of Fungi

Cited by 174 publications

References 58 publications

Influence of an endophytic fungus on host plant selection by a polyphagous moth via volatile spectrum changes

Influence of an endophytic fungus on host plant selection by a polyphagous moth via volatile spectrum changes

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

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

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