This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
Synonyms: DIMBOA biosynthesis
|Superclasses:||Biosynthesis → Secondary Metabolites Biosynthesis|
Expected Taxonomic Range: Magnoliophyta
Benzoxazinoids were identified in the early 1960s as secondary metabolites of the grasses (including the major agricultural crops maize (Zea mays), wheat (Triticum aestivum), and rye (Secale cereale)) that function as natural pesticides and exhibit allelopathic properties [Barnes87, Sicker00]. Benzoxazinoids are synthesized in two subfamilies of the Poaceae and sporadically in single species of the dicots [Frey09]. They play an important role in defense against pests such as insects, pathogenic fungi and bacteria [Niemeyer88]. The most common benzoxazinoids are DIBOA and DIMBOA.
Since the aglycone benzoxazinoids are autotoxic, they are stored in glucosylated forms that have reduced chemical reactivity [Sicker00]. The glucosides are stored in the vacuoles [Osbourn96]. This allows the plants to store the toxic compounds in anticipation of pathogen attacks, prompting the suggestion to name these compounds "phytoanticipins".
About This Pathway
While DIBOA is the main benzoxazinoid in some plants, including barley, in most other benzoxazinoid-producing plants, such as maize, DIBOA-β-D-glucoside is further converted to DIMBOA-β-D-glucoside [Frey09] by a two-step hydroxylation/methylation at position C7, catalyzed by Bx6 and Bx7, respectively [Jonczyk08].
In addition, DIMBOA-β-D-glucoside has been reported to be further methylated in maize into HMDBOA-glucoside [Oikawa02]. HMDBOA-glucoside is relatively lipophilic amongst benzoxazinoid glucosides, a property that may affect its absorption by pathogens at the site of interaction [Oikawa02]. A number of defense reaction elicitors (chitin and chitosan fragments, heavy metal ions such as copper and jasmonic acid) have been shown to lead to the production of HDMBOA-glucoside in wheat, maize and Job's Tears plants [Oikawa01, Oikawa02].
Superpathways: superpathway of benzoxazinoid glucosides biosynthesis
Frey09: Frey M, Schullehner K, Dick R, Fiesselmann A, Gierl A (2009). "Benzoxazinoid biosynthesis, a model for evolution of secondary metabolic pathways in plants." Phytochemistry 70(15-16);1645-51. PMID: 19577780
Jonczyk08: Jonczyk R, Schmidt H, Osterrieder A, Fiesselmann A, Schullehner K, Haslbeck M, Sicker D, Hofmann D, Yalpani N, Simmons C, Frey M, Gierl A (2008). "Elucidation of the final reactions of DIMBOA-glucoside biosynthesis in maize: characterization of Bx6 and Bx7." Plant Physiol 146(3);1053-63. PMID: 18192444
Oikawa01: Oikawa A, Ishihara A, Hasegawa M, Kodama O, Iwamura H (2001). "Induced accumulation of 2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one glucoside (HDMBOA-Glc) in maize leaves." Phytochemistry 56(7);669-75. PMID: 11314951
Oikawa02: Oikawa A, Ishihara A, Iwamura H (2002). "Induction of HDMBOA-Glc accumulation and DIMBOA-Glc 4-O-methyltransferase by jasmonic acid in poaceous plants." Phytochemistry 61(3);331-7. PMID: 12359519
Frey03: Frey M, Huber K, Park WJ, Sicker D, Lindberg P, Meeley RB, Simmons CR, Yalpani N, Gierl A (2003). "A 2-oxoglutarate-dependent dioxygenase is integrated in DIMBOA-biosynthesis." Phytochemistry 62(3);371-6. PMID: 12620350
©2014 SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025-3493