Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2023 Mar 25;15(4):241.
doi: 10.3390/toxins15040241.

Defensive Molecules Momilactones A and B: Function, Biosynthesis, Induction and Occurrence

Hisashi Kato-Noguchi  1
Affiliations
Review

Defensive Molecules Momilactones A and B: Function, Biosynthesis, Induction and Occurrence

Hisashi Kato-Noguchi. Toxins (Basel). .

Abstract

Labdane-related diterpenoids, momilactones A and B were isolated and identified in rice husks in 1973 and later found in rice leaves, straws, roots, root exudate, other several Poaceae species and the moss species Calohypnum plumiforme. The functions of momilactones in rice are well documented. Momilactones in rice plants suppressed the growth of fungal pathogens, indicating the defense function against pathogen attacks. Rice plants also inhibited the growth of adjacent competitive plants through the root secretion of momilactones into their rhizosphere due to the potent growth-inhibitory activity of momilactones, indicating a function in allelopathy. Momilactone-deficient mutants of rice lost their tolerance to pathogens and allelopathic activity, which verifies the involvement of momilactones in both functions. Momilactones also showed pharmacological functions such as anti-leukemia and anti-diabetic activities. Momilactones are synthesized from geranylgeranyl diphosphate through cyclization steps, and the biosynthetic gene cluster is located on chromosome 4 of the rice genome. Pathogen attacks, biotic elicitors such as chitosan and cantharidin, and abiotic elicitors such as UV irradiation and CuCl2 elevated momilactone production through jasmonic acid-dependent and independent signaling pathways. Rice allelopathy was also elevated by jasmonic acid, UV irradiation and nutrient deficiency due to nutrient competition with neighboring plants with the increased production and secretion of momilactones. Rice allelopathic activity and the secretion of momilactones into the rice rhizosphere were also induced by either nearby Echinochloa crus-galli plants or their root exudates. Certain compounds from Echinochloa crus-galli may stimulate the production and secretion of momilactones. This article focuses on the functions, biosynthesis and induction of momilactones and their occurrence in plant species.

Keywords: Echinochloa crus-galli; Oryza sativa; allelopathy; biosynthesis; diterpenoid; elicitation; momilactone; pathogen; rice blast.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Momilactones.
Figure 2
Figure 2
Biosynthetic pathway of momilactones in rice.
Figure 3
Figure 3
Gene cluster on chromosome 4 of rice genome for momilactone biosynthesis.
Figure 4
Figure 4
Signaling pathway for the elicitation of rice momilactone biosynthesis.
See this image and copyright information in PMC

References

    1. Kato T., Kabuto C., Sasaki N., Tsunagawa M., Aizawa H., Fujita K., Kato Y., Takahashi N. Momilactones, growth inhibitors from rice, Oryza sativa L. Tetrahedron Lett. 1973;39:3861–3864. doi: 10.1016/S0040-4039(01)87058-1. - DOI
    1. Cartwright D., Langcake P., Pryce R.J., Leworthy D.P., Ride J.P. Chemical activation of host defense mechanisms as a basis for crop protection. Nature. 1977;267:511–513. doi: 10.1038/267511a0. - DOI
    1. Cartwright D.W., 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. doi: 10.1016/S0031-9422(00)84189-8. - DOI
    1. Takahashi A., Kawasaki T., Henmi K., Shii K., Kodama O., Satoh H., Shimamoto K. Lesion mimic mutants of rice with alterations in early signaling events of defense. Plant J. 1999;17:535–545. doi: 10.1046/j.1365-313X.1999.00405.x. - DOI - PubMed
    1. Hasegawa M., Mitsuhara I., Seo S., Imai T., Koga J., Okada K., Yamane H., Ohashi Y. Phytoalexin accumulation in the interaction between rice and the blast fungus. Mol. Plant-Micro. Intrac. 2010;23:1000–1011. doi: 10.1094/MPMI-23-8-1000. - DOI - PubMed

Publication types