Variation Endogenus and Exogenous of Allelochemical 2,4-dihydroxy-7-metoxy-1,4-benzoxazin-3,(4&lt;i&gt;H&lt;/i&gt;)-one (DIMBOA) in Root Architecture of Maize (&lt;i&gt;Zea mayz&lt;/i&gt;)

Alberto Oliveros-Bastidas,José M.G Molinillo,Francisco A Macías

doi:10.5923/j.ijaf.20120203.09

Abstract

The concentrations of hydroxamic acids 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3(4H)-one (DIMBOA), in roots and root exudate of 1- to 6- days-old maize plants were determined by high-performance liquid chromatography (HPLC). The highest concentrations of DIMBOA were found in maize root extracts and exudate when maize roots were 2 weeks old and the maize plant was approximately 15 cm in height. The highest concentrations of DIMBOA equivalents were found in root crown. The distribution of DIMBOA in different root parts (seminal roots, primary root, and crown) was also determined. DIMBOA is concentrated in the cortex of all parts of maize roots determined. The concentrations in com- plete organ of nodal roots were significantly higher than any other parts of maize roots. The results indicate that the distri- bution of DIMBOA is heterogeneous within architecture of the root. Different groups of root show different potential root exudation of DIMBOA. The level of endogenous DIMBOA directly correlates with exogenous levels. The high concentra- tions of these substances in the maize root are may be relevant in the resistance of maize varieties to subterranean pest insects.

Highlights

Cyclic hydroxamic acids and their derivatives are major secondary metabolites among poaceous plants
The benzoxazinoid glucosides are stored in vacuoles as inactive phytoanticipines, while the glucosidases specific for their activation are present in the plastids [6, 7]
Upon exogenous or endogenous damage to tissues, the glucoside comes in contact with the glusosidase and the toxic aglucone, DIMBOA (2-4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one), is released [8,9,10]

Summary

Introduction

Cyclic hydroxamic acids and their derivatives (benzoxazinoids) are major secondary metabolites among poaceous plants. These compounds have biological activity against plants, insects, fungi, and microorganisms [1,2] and could be involved in detoxification of toxic inorganic molecules [3]. The main hydroxamic acid in maize (Zea mays L.) is the 2- ß-D-glucopyranosyloxy-4-hydroxy-7methoxy-1,4-benzoxazin-3-one (DIMBOA-Glc) [4,5]. The benzoxazinoid glucosides are stored in vacuoles as inactive phytoanticipines, while the glucosidases specific for their activation are present in the plastids [6, 7]. Upon exogenous or endogenous damage to tissues, the glucoside comes in contact with the glusosidase and the toxic aglucone, DIMBOA (2-4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one), is released [8,9,10].

Methods

Findings

Discussion

Conclusion