Mycopathologia

, Volume 153, Issue 1, pp 41–48

Association of aflatoxin biosynthesis and sclerotialdevelopment in Aspergillus parasiticus

  • Perng-Kuang Chang
  • Joan W. Bennett
  • Peter J. Cotty
Article

Abstract

Secondary metabolism in fungi is frequently associated with asexual and sexual development. Aspergillus parasiticus produces aflatoxins known to contaminate a variety of agricultural commodities. This strictly mitotic fungus, besides producing conidia asexually, produces sclerotia, structures resistant to harsh conditions and for propagation. Sclerotia are considered to be derived from the sexual structure, cleistothecia, and may represent a vestige of ascospore production. Introduction of the aflatoxin pathway-specific regulatory gene, aflR, and aflJ, which encoded a putative co-activator, into an O-methylsterigmatocystin (OMST)-accumulating strain,A. parasiticus SRRC 2043, resulted in elevated levels of accumulation of major aflatoxin precursors, including norsolorinic acid (NOR), averantin (AVN), versicolorin A (VERA) and OMST. The total amount of these aflatoxin precursors, NOR, VERA, AVN and OMST, produced by the aflR plus aflJ transformants was two to three-fold that produced by the aflR transformants. This increase indicated a synergisticeffect of aflR and aflJ on the synthesis of aflatoxin precursors. Increased production of the aflatoxin precursors was associated with progressive decrease in sclerotial size, alteration in sclerotial shape and weakening in the sclerotial structure of the transformants. The results showed that sclerotial development and aflatoxin biosynthesis are closely related. We proposed that competition for a common substrate, such as acetate, by the aflatoxin biosynthetic pathway could adversely affect sclerotial development in A. parasiticus.

Aspergillus parasiticus aflatoxins sclerotia 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Adams TH, Yu JH. Coordinate control of secondary metabolite production and asexual sporulation in Aspergillus nidulans. Curr Opin Microbiol 1998; 1: 674–677.PubMedCrossRefGoogle Scholar
  2. 2.
    Kurtzman CP, Horn BW, Hesseltine CW. Aspergillus nomius, a new aflatoxin-producing species related to Aspergillus flavus and Aspergillus tamarii. Antonie Leeuwenhoek J Microbiol 1987; 53: 147–158.CrossRefGoogle Scholar
  3. 3.
    Bhatnagar D, Cleveland TE, Brown RL, Cary JW, Yu J, Chang P-K. Preharvest aflatoxin contamination: Elimination through biotechnology. In: Dhaliwal GS, Randhawa NS, Arora R, Dhawan AK, eds. Ecological Agriculture and Sustainable Development. Vol. 1, Indian Ecological Society and Center for Research in Rural & Industrial Development. New Delhi: Chaman Enterprises, 1998; 110–129.Google Scholar
  4. 4.
    Cotty PJ. Aflatoxin and sclerotial production by Aspergillus flavus: Influence of pH. Phytopathology 1988; 78: 1250–1253.Google Scholar
  5. 5.
    Wicklow DT, Shotwell L. Intrafungal distribution of aflatoxins among conidia and sclerotia of Aspergillus flavus and Aspergillus parasiticus. Can J Microbiol 1983; 29: 1–5.PubMedCrossRefGoogle Scholar
  6. 6.
    Rollins JA, Dickman MA. Increase in endogenous and exogenous cyclic AMP levels inhibits sclerotial development in Sclerotinia sclerotiorum. Appl Environ Microbiol 1998; 64: 2539–2544.PubMedGoogle Scholar
  7. 7.
    Geiser DM, Timberlake WE, Arnold ML. Loss of meiosis in Aspergillus. Mol Bio Evol 1996; 13: 809–817.Google Scholar
  8. 8.
    Yager LN. Early developmental events during asexual and sexual sporulation in Aspergillus nidulans. In: Bennett JW, Klich MA, eds. Aspergillus — Biology and Industrial Applications. Boston: Butterworth-Heinemann, 1992; 19–41.Google Scholar
  9. 9.
    Bennett JW, Horowitz PC, Lee LS. Production of sclerotia by aflatoxigenic and nonaflatoxigenic strains of Aspergillus flavus and A. parasiticus. Mycologia 1979; 71: 415–422.PubMedGoogle Scholar
  10. 10.
    Mehan VK. Reddy SV, Nahdi S, McDonald D, Jayanthi S. Aflatoxin-producing potential of various strains of Aspergillus flavus from groundnut field in different soil types. Int Arachis Newslett 1995; 15: 42–43.Google Scholar
  11. 11.
    Wang Z-G, Tong Z, Cheng S-Y, Cong L-M. Study on pectinase and sclerotium producing abilities of two kinds of Aspergillus flavus isolates from Zhejiang. Mycopathologia 1993; 121: 163–168.CrossRefGoogle Scholar
  12. 12.
    Guzman-de-Pena D, Ruiz-Herrera J. Relationship between aflatoxin biosynthesis and sporulation in Aspergillus parasiticus. Fungal Genet Biol 1997; 21: 198–205.PubMedCrossRefGoogle Scholar
  13. 13.
    Cotty PJ. Virulence and cultural characteristics of two Aspergillus flavus strains pathogenic on cotton. Phytopathology 1989; 79: 808-814.Google Scholar
  14. 14.
    Horn BW, Dorner JW. Regional differences in production of aflatoxin B1 and cyclopiazonic acid by soil isolates of Aspergillus flavus along a transect within United States. Appl Environ Microbiol 1999; 65: 1444–1449.PubMedGoogle Scholar
  15. 15.
    Mahanti N, Bhatnagar D, Cary JW, Joubran J, Linz JE. Structure and function of fas-1A, a gene encoding a putative fatty acid synthetase directly involved in aflatoxin biosynthesis in Aspergillus parasiticus. Appl Environ Microbiol 1995; 62: 191–195.Google Scholar
  16. 16.
    Trail F, Mahanti N, Rarick M, Mehigh R, Liang S-H, Zhou R, Linz JE. A physical and transcriptional map of an aflatoxin gene cluster in Aspergillus parasiticus and the functional disruption of a gene involved in the aflatoxin pathway. Appl Environ Microbiol 1995; 61: 2665–2673.PubMedGoogle Scholar
  17. 17.
    Skory CD, Chang P-K, Cary JW, Linz JE. Isolation and characterization of a gene from Aspergillus parasiticus associated with conversion of versicolorin A to sterigmatocystin in aflatoxin biosynthesis. Appl Environ Microbiol 1992; 58: 3527–3537.PubMedGoogle Scholar
  18. 18.
    Chang P-K, Ehrlich KC, Yu J, Bhatnagar D, Cleveland TE. Increased expression of Aspergillus parasiticus aflR, encoding a sequence-specific DNA-binding protein, relieves nitrate inhibition of aflatoxin biosynthesis. Appl Environ Microbiol 1995; 61: 2372–2377.PubMedGoogle Scholar
  19. 19.
    Ehrlich KC, Montalbano BG, Bhatnagar D, Cleveland TE. Alteration of different domains in AFLR affects aflatoxin pathway metabolism in Aspergillus parasiticus transformants. Fungal Genet Biol 1998; 23: 279–287.PubMedCrossRefGoogle Scholar
  20. 20.
    Chang P-K, Yu J, Bhatnagar D, Cleveland TE. Repressor-AFLR interaction modulates aflatoxin biosynthesis in Aspergillus parasiticus. Mycopathologia 1999; 147: 105–112.PubMedCrossRefGoogle Scholar
  21. 21.
    Meyers DM, Bhatnagar D, Payne GA. Characterization of aflJ, a gene involved in aflatoxin biosynthesis. Appl Environ Microbiol 1998; 64: 3713–3717.PubMedGoogle Scholar
  22. 22.
    Yu J, Chang P-K, Ehrlich KC, Cary JW, Montalbano BG, Dyer JM, Bhatnagar D, Cleveland TE. Characterization of critical amino acids of an Aspergillus parasiticus cytochrome P-450 monooxygenase encoded by ordA that is involved in biosynthesis of aflatoxins B1, G1, B2, and G2. Appl Environ Microbiol 1998; 64: 4834–4841.PubMedGoogle Scholar
  23. 23.
    Horng JS, Chang P-K, Pestka JJ, Linz JE. Development of a homologous transformation system for Aspergillus parasiticus with the gene encoding nitrate reductase. Mol Gen Genet 1990; 224: 294–296.PubMedCrossRefGoogle Scholar
  24. 24.
    Cleveland TE, Bhatnagar D, Brown RL. Aflatoxin production via cross-feeding of pathway precursors during coferment-48 ation of aflatoxin pathway-blocked Aspergillus parasiticus mutants. Appl Environ Microbiol 1991; 57: 2907–2911.PubMedGoogle Scholar
  25. 25.
    Kale SP, Cary JW, Bhatnagar D, Bennett JW. Characterization of experimentally induced, nonaflatoxigenic variant strains of Aspergillus parasiticus. Appl. Environ. Microbiol. 1996; 62: 3399–3404.PubMedGoogle Scholar
  26. 26.
    Ehrlich KC, Montalbano BG, Cary JW. Binding of the C6-zinc cluster protein, AFLR, to the promoters of aflatoxin pathway biosynthesis genes in Aspergillus parasiticus. Gene 1999; 230: 249–257.PubMedCrossRefGoogle Scholar
  27. 27.
    Woloshuk CP, Foutz KR, Brewer JW, Bhatnagar D, Cleveland TE, Payne GA. Molecular characterization of aflR, a regulatory locus for aflatoxin biosynthesis. Appl Environ Microbiol 1994; 60: 2408–2414.PubMedGoogle Scholar
  28. 28.
    Yu J-H, Butchko RAE, Fernandes M, Keller NP, Leonard TJ, Adams TH. Conservation of structure and function of the aflatoxin regulatory gene aflR from Aspergillus nidulans and A. flavus. Curr Genet 196; 29: 549–555.Google Scholar
  29. 29.
    Näär MA, Beaurang PA, Zhou S, Abraham S, Solomon W, Tjian R. Composite coactivator ARC mediates chromatindirected transcriptional activation. Nature 1999; 398: 828–832.PubMedCrossRefGoogle Scholar
  30. 30.
    Takemaru K, Harashima S, Ueda H, Hirose S. Yeast coactivator MBF1 mediates GCN4-dependent transcriptional activation. Mol Cell Biol 1998; 18: 4971–4976.PubMedGoogle Scholar
  31. 31.
    Cotty, PJ, Bayman P, Egel DS, Elias KS. Agriculture, Aflatoxins and Aspergillus. In: Powell KA, Renwick A, Peberdy JF eds. The Genus Aspergillus: From Taxonomy and Genetics to Industrial Application. New York: Prenum Press, 1994; 1–27.Google Scholar
  32. 32.
    Littley ER, Rahe JE. Sclerotial morphogenesis in Sclerotium cepivorum in vitro. Can J Bot 1992; 70: 772–778.Google Scholar
  33. 33.
    Willetts HJ, Bullock S. Developmental biology of sclerotia. Mycol Res 1992; 10: 801–816.CrossRefGoogle Scholar
  34. 34.
    Marhoul JF, Adams TH. Identification of developmental regulatory genes in Aspergillus nidulans by overexpression. Genetics 1995; 139: 537–547.PubMedGoogle Scholar
  35. 35.
    Hicks JK, Yu J-H, Keller NP, Adams TH. Aspergillus sporulation and mycotoxin production both require inactivation of the FadA Gα protein-dependent signaling pathway. EMBO J 1997; 16: 4916–4923.PubMedCrossRefGoogle Scholar
  36. 36.
    Zhou R, Rasooly R, Linz JE. Isolation and analysis of flup, a gene associated with hyphal growth and sporulation in Aspergillus parasiticus. Mol Gen Genet 2000; 264: 514–520.PubMedCrossRefGoogle Scholar
  37. 37.
    Guzman-de-Pena D, Aguirre J, Ruiz-Herrera J. Correlation between the regulation of sterigmatocystin biosynthesis and asexual and sexual sporulation in Emericella nidulans. Antonie van Leeuwenhoek 1998; 73: 199–205.PubMedCrossRefGoogle Scholar
  38. 38.
    Calvo AM, Hinze LL, Gardner HW, Keller NP. Sporogenic effect of polyunsaturated fatty acids on development of Aspergillus spp. Appl Environ Microbiol 1999; 65: 3668–3673.PubMedGoogle Scholar
  39. 39.
    Larroche C. Microbial growth and sporulation behavior in solid state fermentation. J Sci Ind Res 1996; 55: 408–423.Google Scholar
  40. 40.
    Payne GA, Brown MP. Genetics and physiology of aflatoxin biosynthesis. Annu Rev Phytopathol 1998: 36: 329–362.PubMedCrossRefGoogle Scholar
  41. 41.
    Marukawa S, Funakawa S, Satomura Y. Role of sclerin on morphogenesis in Sclerotinia sclerotiorum de Bary. Agr Biol Chem 1975; 3: 645–650.Google Scholar
  42. 42.
    Vidal-Croa A, Viviani F, Labesse G, Boccara M, Gaudry M. Polyhydroxynaphthalene reductase involved in melanin biosynthesis in Magnoporthe grisea. Eur J Biochem 1994; 219: 985–992.CrossRefGoogle Scholar

Copyright information

© Kluwer Academic Publishers 2002

Authors and Affiliations

  • Perng-Kuang Chang
    • 1
  • Joan W. Bennett
    • 2
  • Peter J. Cotty
    • 1
  1. 1.Southern Regional Research Center, Agricultural Research ServiceU.S. Department of AgricultureNew OrleansUSA
  2. 2.Department of Cell and Molecular BiologyTulaneUniversityNew OrleansUSA

Personalised recommendations