Part of the Disease Management of Fruits and Vegetables book series (DMFV, volume 2)


Allelochemicals play an important role in biological control of plant pathogens and diseases. Weed Ageratum conyzoides L. and food crop Oryza sativa L. can produce and release many kinds of allelochemicals participating in their defense against pathogens. The essential oil from A. conyzoides has been found to have significant negative effects on several plant pathogens. In the A. conyzoides intercropped citrus orchard, A. conyzoides released allelopathic flavones and agreatochromene into the soil to reduce the populations of soil pathogenic fungi Phytophthora citrophthora, Pythium aphanidermatum and Fusarium solani. Further research revealed that ageratochromene underwent a reversible transformation in the soils, that is, ageratochromene released from A. conyzoides plants was transformed into its dimers, and the dimers can be remonomerized in the soils. The reversible transformation between ageratochromene and its dimers in the A. conyzoides intercropped citrus orchard soil can be an important mechanism maintaining bioactive allelochemicals at an effective concentration, thus, sustaining the inhibition of pathogenic fungi in soil. Many kinds of allelochemicals in rice were identified. Among them, alkylresorcinols, flavone and cyclohexenone had high antifungal activities on Pyricularia oryzae and Rhizoctonia solani. Furthermore, these antifungal allelochemicals formed by rice can be triggered by a large number of abiotic and biotic factors. Antifungal allelochemicals from rice mainly involved two types of diterpenes and flavones, including momilactones A and B, oryzalexins A-F and S, phytocassanes A-E and sakuranetin. These compounds help rice establishing its own pathogen defense mechanism. However, it remains obscure which allelochemicals in rice are predominantly involved in defense mechanisms against the pathogens. Therefore, further clarification of the resistance mechanism and multiple functions of these compounds on rice are warranted.


Spore Germination Rhizoctonia Solani Citrus Orchard Allelopathic Potential Pythium Aphanidermatum 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


  1. Adesogan, E.K., Okunade, A.L. A new flavone from Ageratum conyzoides. Phytochemistry 1979; 18:1863–1864. CrossRefGoogle Scholar
  2. Akatsuka, T., Kodama, Q, Sekido, H., Kono, Y, Takeuchi, S. Novel phytoalexins (Oryzalexins A, B and C) isolated from rice blast leaves infected with Pyricularia oryxae. Part I: Isolation, characterization and biological activities of oryzalexins. Agric Biol Chem 1985; 49:1689–1694. Google Scholar
  3. Albersberg, W. G. L. Singh, Y. Essential oil of Ageratum conyzoides.Flavor Fragrance J 1991; 6: 117–120. Google Scholar
  4. Bailey, J. A., Mansfield, J. W. eds. Phytoalexins. John Wiley and Sons Inc., New York, 1982. Google Scholar
  5. Biond, D., Cianci, P., Geraci, C. Antimicrobial activity and chemical composition of essential oil from Sicilian aromatic plants. Flavor Fragrance 1993; 8:331–337. Google Scholar
  6. Cartwright, D., Langcake, P., Pryce, R. J., Leworthy, D. P. Chemical activation of host defence mechanisms as a basis for crop protection. Nature 1977; 267:511–523. CrossRefGoogle Scholar
  7. Cartwright, D., Langcake, P., Pryce, R.J., Leworthy, D.P. Ride, J.P. Isolation and characterization of two phytoalexins from rice as momilactones A and B. Phytochemistry 1981; 20:535–537 CrossRefGoogle Scholar
  8. Chung, I.M., Ahn, J.K., Yun, S.J. Identification of allelopathic compounds from rice (Oryza sative L.) straw and their biological activity. Can J Plant Sci 2001; 81:815–819. Google Scholar
  9. Dangl, J.L., Jones, J.D.G. Plant pathogens and integrated defence responses to infection. Nature 2001; 411:826–8335. PubMedCrossRefGoogle Scholar
  10. Darvill, A.G., Albersheim, P. Phytoalexins and their elicitors-A defense against microbial infection in plants. Ann Rev Plant Pathol 1984; 35:243–275. CrossRefGoogle Scholar
  11. Dixit, S.N., Chandra, H., Tiwari, R., Dixit, V. Development of a botanical fungicide against blue mould of mandarins. J Stored Prod Res 1995; 31:165–172. CrossRefGoogle Scholar
  12. Dixon, R.A. Natural products and plant disease resistance. Nature 2001; 411:843–847. PubMedCrossRefGoogle Scholar
  13. Ekundayo, O., Laakso, I., Hiltunen, R. Essential oil of A. conyzoides. Planta Med 1988; 54:55–57. PubMedGoogle Scholar
  14. Gonzalez, A.G., Aguiar, Z.E., Grillo, T.A., Luis, J.G., Rivera, A., Calle, J. Methoxyflavones from Ageratum conyzoides. Phytochemistry 1991; 30:1269–1271. CrossRefGoogle Scholar
  15. Grayer, R.J. Harborne, J.B. A survey of antifungal compounds from higher plants. Phytochemistry 1994; 37:19–42. Google Scholar
  16. Hammerschmidt, R. Phytoalexins: what have we learned after 60 years? Annu Rev Phytopathol 1999; 37:285–306. PubMedCrossRefGoogle Scholar
  17. Harborne, J.B. The comparative biochemistry of phytoalexin induction in plants. Biochem System Ecol 1999; 27:335–367. CrossRefGoogle Scholar
  18. Horie, T., Tominaga, H. Kawamura, Y. Revised structure of a natural flavone from Ageratum conyzoides. Phytochemistry 1993; 32:1078–1077 CrossRefGoogle Scholar
  19. Hu, F., Kong, C.H. Allelopathy of Ageratum conyzoides.VI. Effects of meteorological conditions on allelopathy of Ageratum conyzoides.Chin J Appl Ecol 2002a; 13:76–80. (In Chinese) Google Scholar
  20. Hu, F., Kong, C.H. Inhibitory effect of flavones from Ageratum conyzoides on the major pathogens in citrus orchard. Chin J Appl Ecol 2002b; 13:1166–1168 (In Chinese) Google Scholar
  21. Jhansi, P., Ramanujam, C.G.K. Pollen analysis of extracted and squeezed honey of Hyderabad. India Geophytol 1987; 17:237–240. Google Scholar
  22. Kato, H., Kodama, O., Akatsuka, T. Oryzalexin E, a diterpene phytoalexin from UV-irradiat rice leaves. Phytochemistry 1993; 33:79–81. CrossRefGoogle Scholar
  23. Kato, H., Kodama, O., Akatsuka, T. Oryzalexin F, a diterpene phytoalexin from UV-irradiat rice leaves. Phytochemistry 1994; 36:299–301. CrossRefGoogle Scholar
  24. Kato-Noguchi, H., Ino, T., Sata, N., Yamamura, S. Isolation and identification of a potent allelopathic substance in rice root exudates. Physiol Planta 2002; 115:401–405. CrossRefGoogle Scholar
  25. Kato-Noguchi, H., Ino, K. Rice seedlings release momilactone B into the environment. Phytochemistry 2003; 63:551–554. PubMedCrossRefGoogle Scholar
  26. Kim, K.U., Shin, D.H. eds. Rice Allelopathy Kyungpook National University. Taegu(Korea) 2000. Google Scholar
  27. Kato, T., Tsunakawa, M., Sasaki, N. Growth and germination inhibitors in rice husks. Phytochemistry 1977; 16:45–48. CrossRefGoogle Scholar
  28. Kodama, O., Li, W. X., Tamogami, S., Akatsuka, T. Oryzalexin S, a novel stemarane-type diterpene rice phytoalexin. Biosci Biotech Biochem 1992; 56:1002–1003. CrossRefGoogle Scholar
  29. Koga, J., Ogawa, N., Yamauchi, T., Kikuchi, M., Ogasawara, N., Shimura, M. Functional moiety for the antifungal activity of phytocassane E, a diteroene phytoalexin from rice. Phytochemistry 1997; 44:249–253. CrossRefGoogle Scholar
  30. Koga, J., Shimura, M., Oshima, K., Ogawa, N., Yamauchi, T., Ogasawara, N. Phytocassanes A, B, C and D, novel diterpene phytoalexins from rice, Oryza sativa L. Tetrahedron 1995; 51:7907–7918. CrossRefGoogle Scholar
  31. Kong, C.H., Hu, F., Xu, T., Lu, Y.H. Allelopathic potential and chemical constituents of volatile oil from Ageratum conyzoides. J Chem Ecol 1999; 25:2347–2356. CrossRefGoogle Scholar
  32. Kong, C.H., Huang, S.S., Hu, F. Allelopathy of Ageratum conyzoides.V. Biological activities of the volatile oil from Ageratum on fungi, insects and plants and its chemical constituents. Acta Ecol Sin 2001; 21:584–587. (In Chinese). Google Scholar
  33. Kong, C.H., Hu, F., Xu, X. H. Allelopathic potential and chemical constituents of volatile from Ageratum conyzoides under stress. J Chem Ecol 2002a; 28:1173–1182. CrossRefGoogle Scholar
  34. Kong, C.H., Xu, X.H., Hu, F., Cheng, X.H., Lin, B., Tan, Z.W. Using specific secondary metabolite as marker to evaluate allelopathic potential of rice variety and individual plant. Chin Sci Bull 2002b; 47:839–843. CrossRefGoogle Scholar
  35. Kong, C.H., Hu, F., Liang, W.J., Wang, P., Jiang, Y. Allelopathic potential of Ageratum conyzoides with different growth stages and habitats. Allelopathy J 2004a; 13:233–240. Google Scholar
  36. Kong, C.H., Hu, F., Xu, X.H., Liang, W.J., Zhang, C.X. Allelopathic plant: Ageratum conyzoides L. Allelopathy J 2004b; 14:5–13. Google Scholar
  37. Kong, C.H., Liang, W. J., Hu, F., Xu, X. H. Wang, P., Jiang, Y. Allelochemicals and their transformations in the Ageratum conyzoides intercropped the citrus orchard soil. Plant Soil 2004c; 264:149–157. CrossRefGoogle Scholar
  38. Kong, C.H., Liang, W.J., Xu, X.H., Hu, F., Wang, P., Jiang, Y. Release and activity of allelochemicals from allelopathic rice seedlings. J Agric Food Chem 2004d; 52:2861–2865. CrossRefGoogle Scholar
  39. Kong, C.H., Xu, X. H., Zhou, B., Hu, F., Zhang, C.X., Zhang, M.X. Two compounds from allelopathic rice accession and their inhibitory effects on weeds and fungal pathogens. Phytochemistry 2004e; 65:1123–1128. CrossRefGoogle Scholar
  40. Kossmann, G., Groth, D. Plantea Infestantes e Nocivas. BASF Brasileira, São Paulo, 1993. Google Scholar
  41. Ladeira, A.M., Zaidan, L.B.P., Figueiredo, Ribeiro, R.D.C.L. Ageratum conyzoides L.(Compositae): germination, flowering and occurrence of phenolic derivatives at different stages of development. Hoehnea 1987; 14:53–62. Google Scholar
  42. Lee, C.W., Yoneyama, K., Takeuchi, Y., Konnai, M., Tamogami, S., Kodama, O. Momilactones A and B in rice straw harvested at different growth stages. Biosci Biotech Biochem 1999; 63:1318–1320. CrossRefGoogle Scholar
  43. Liang, W.G., Hunag, M.D. Influence of citrus orchard ground cover plants on anthropod communities in China: a review. Agric Ecosyst Environ 1994; 50:29–37. CrossRefGoogle Scholar
  44. Mattice, J., Lavy, T., Skulman, B., Dilday, R. Searching for allelochemicals in rice that control ducksalad. In Allelopathy In Rice; Olofsdotter, M. Ed. International Rice Research Institute: Manila, Philippines, 1998; pp. 81–97. Google Scholar
  45. Menut, C., Lamaty, G., Zollo, P.H.A. Aromatic plants of tropical central Africa: Part X. Chemical composition of essential oil of Ageratum houstonianum and Ageratum conyzoides from Cameroon. Flavor Fragrance J 1993; 8:1–4. Google Scholar
  46. Ming, L.C. Ageratum conyzoides: A tropical source of medicinal and agricultural products. In: Perspectives on New Crops and New Uses,Janick, J. eds. Alexandria, VA USA: ASHS Press 1999; pp 469–473. Google Scholar
  47. Muller, K.O., Borger, H. Experimentelle Untersuchungen uber die Phytophthora-Resistenz der Kartoffel-zugleich ein Bewitrag zum Problem der “erworbenen Resistenz” im Pflanzenreich. Arb Biol Anst Reichsanst (Berl) 1940; 23:189–231. Google Scholar
  48. Nakazato, Y., Tamogami, S., Kawai, H., Hasegawa, M., Kodama, O. Methionine-induced phytoalexin production in rice leaves. Biosci Biotech Biochem 2000; 64:577–583. CrossRefGoogle Scholar
  49. Okunade, A. L. Ageratum conyzoides L.(Asteraceae). Fitoterapia 2002; 73:1–16. PubMedCrossRefGoogle Scholar
  50. Olofsdotter, M., Rebulanan, M., Madrid, A., Wang, D.L., Navarez, D., Olk, D.C. Why phenolic acids are unlikely primary allelochemicals in rice. J Chem Ecol 2002; 28:229–241. PubMedCrossRefGoogle Scholar
  51. Pari, K., Rao, P. J., Subrahmanyam, B., Rasthogi, J. N., Devakumar, G. Benzofuran and other constituents of the essential oil of Ageratum conyzoides. Phytochemistry 1998; 49:1385–1388. CrossRefGoogle Scholar
  52. Rao, G. P., Pandey, A. K., Shukla, K. Essential oils of some higher plants vis-à-vis some legume viruses. Indian Perfumer 1986; 30:483–486. Google Scholar
  53. Rice, E.L. Biological Control of Weeds and Plant Diseases: Advances in Applied Allelopathy. University of Oklahoma Press, Norman, OK, 1995. Google Scholar
  54. Rimando, A.M., Olofsdotter, M., Dayan, F.E., Duke, S.O. Searching for rice allelochemicals: An example of bioassay-guided isolation. Agron J 2001; 93:16–20. CrossRefGoogle Scholar
  55. Schaffrath, U., Scheinpflug, H., Reisener, H.J. An elicitor from Pyricularia oryzae induced resistance responses in rice: isolation, Characterization and physiological properties. Physiol Mol Plant Pathol 1995; 46:293–307. CrossRefGoogle Scholar
  56. Stadler, J., Mungai, G., Brandl, R. Weed invasion in East Africa: insights from herbarium records. African J Ecol 1998; 36:15–22. CrossRefGoogle Scholar
  57. Stuiver, M.H., Custers, J.H.H.V. Engineering disease resistance in plants. Nature 2001; 411:865–868. PubMedCrossRefGoogle Scholar
  58. Suzuki, Y., Esumi, Y., Hyakutake, H., Kono, Y., Sakurai, A. Isolation of 5-(8.Z-heptadecenyl)-resorcinol from etiolated rice seedlings as an antifungal agent. Phytochemistry 1996; 41:1485–1489. CrossRefGoogle Scholar
  59. Suzuki, Y., Esumi, Y., Saito T, Kishimoto Y, Morita T. Identification of 5-n-(2.-oxo)alkylresorcinols from etiolated rice seedlings. Phytochemistry 1998; 47:1247–1252. CrossRefGoogle Scholar
  60. Tamogami, S., Rakwal, R., Kodama, O. Phytoalexin production by amino acid conjugates of jasmonic acis through induction of naringenin-7-o-methyltransferase, a key enzyme on phytoalexin biosynthesis in rice (Oryza sativa L.). FEBS Lett 1997a; 401:239–242. CrossRefGoogle Scholar
  61. Tamogami, S., Rakwal, R., Kodama, O. Phytoalexin production elicited by exogenously applied jasmonic acid in rice leaves (Oryza sativa L.) is under the control of cytokinins and ascorbic acid. FEBS Lett 1997b; 412:61–64. CrossRefGoogle Scholar
  62. Wandji, J., Bissangou, M. F., Ouambra, J. M., Silou, T., Abena, A. A., Keita, A. The essential oil from Ageratum conyzoides.Fitoterapia 1996; 67, 427–431. Google Scholar

Copyright information

© Springer 2006

Authors and Affiliations

  1. 1.Institute of Applied EcologyChinese Academy of SciencesShenyangChina
  2. 2.South China Agricultural UniversityGuangzhouChina

Personalised recommendations