DIMBOA
Chemical compound
From Wikipedia, the free encyclopedia
DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one) is a naturally occurring hydroxamic acid, a benzoxazinoid. DIMBOA is a powerful antibiotic present in maize, wheat, rye, and related grasses,[1]
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| Names | |
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| Preferred IUPAC name
2,4-Dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one | |
| Identifiers | |
3D model (JSmol) |
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PubChem CID |
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CompTox Dashboard (EPA) |
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| Properties | |
| C9H9NO5 | |
| Molar mass | 211.173 g·mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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DIMBOA was first identified in maize in 1962 as the "corn sweet substance".[2] Etiolated maize seedlings have a very sweet, almost saccharin-like taste due to their high DIMBOA content.
The biosynthesis pathway leading from maize primary metabolism to the production of DIMBOA has been fully identified.[3][4] DIMBOA is stored as an inactive precursor, DIMBOA-glucoside, which is activated by glucosidases in response to insect feeding,[1]
In maize, DIMBOA functions as natural defense against European corn borer (Ostrinia nubilalis) larvae,[5][6] beet armyworms (Spodoptera exigua),[7] corn leaf aphids (Rhopalosiphum maidis),[8] other damaging insect pests, and pathogens, including fungi and bacteria.[1][9][10] The exact level of DIMBOA varies between individual plants,[11][12] but higher concentrations are typically found in young seedlings and the concentration decreases as the plant ages.[13] Natural variation in the Bx1 gene influences the DIMBOA content of maize seedlings.[11][14] In adult maize plants, the DIMBOA concentration is low, but it is induced rapidly in response to insect feeding.[15] The methyltransferases Bx10, Bx11, and Bx12 convert DIMBOA into HDMBOA (2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one), which can be more toxic for insect herbivores.[12][7]
In addition to serving as a direct defensive compound due to its toxicity, DIMBOA can also function as a signaling molecule, leading to the accumulation of callose in response to treatment with chitosan (a fungal elicitor) and aphid feeding.[12][16]
DIMBOA can also form complexes with iron in the rhizosphere and thereby enhance maize iron supply.[17]
Specialized insect pests such as the western corn rootworm (Diabrotica virgifera virgifera) can detect complexes between DIMBOA and iron and use these complexes for host identification and foraging.[17]