Benzoxazinoids - protective secondary metabolites in cereals: Biochemistry and genetic control

Benzoxazinoids (1,4-benzoxazin-3(4H)-one derivatives, BXs) are plant secondary metabolites that play a crucial role in plant resistance to insects, fungi, bacteria and nematodes, and in weed suppression during early plant life. These biochemicals are constitutive compounds found in some members of the family Poaceae and have been studied in detail in maize (Zea mays L.), wheat (Triticum aestivum L.) and rye (Secale cereale L.). The most effective allelopathic benzoxazinoids are 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA) and 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA), classified as hydroxamic acids. Aiming to draw attention to the importance of BXs in plant defence and their potential application in cereal protection, this review summarises the recent findings in genetic control, biochemical pathways, and the mode of action of these secondary metabolites and addresses unresolved questions related to BXs.