Hydroxamic acid content of triticum species

Benzoxazinones are naturally occurring secondary metabolites of some Gramineae plants, responsible for their resistance to some pathogenic fungi and for their allelopathic action. Six varieties of winter wheat grown in fields under organic or conventional systems and 11 old accessions were tested for two consecutive seasons and three plant development stages for the concentration in their roots of cyclic hydroxamic acids and their degradation products. This is the first report of six benzoxazinones analyzed in plants grown in the field. An analytical technique employing LC-DAD was used for determination. It was shown that 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one, its degradation product 6-methoxybenzoxazolin-2-one, and the lactam 2-hydroxy-7-methoxy-1,4-benzoxazin-2-one were predominant compounds in all tested samples. Their concentrations significantly differed with plant development stage and season, but no significant differences were found between varieties and between plant cultivation systems. The concentrations of 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA) and its degradation product benzoxazolin-2-one (BOA) were much lower, ranging from 60 to 430 mg/kg of dry matter, depending on accession, stage of development, and season. There was no significant difference found between plants grown in different cultivation systems, but there were significant differences between old and new varieties; concentrations of DIBOA and its derivatives were significantly lower in old accessions. It was concluded that the concentrations of DIBOA and BOA, which are precursors of highly fungicidal 2-aminophenol, 2-amino-3H-phenoxazin-3-one, and 2-acetylamino-3H-phenoxazin-3-one, are theoretically high enough to protect plants against some soilborne pathogens.

Section: Resultsmentioning

confidence: 57%

Concentration of Benzoxazinoids in Roots of Field-Grown Wheat (Triticum aestivum L.) Varieties

Stochmal

Kuś

Martyniuk

et al. 2006

“…Several authors present the levels of some allelochemicals in wheat seedlings. The concentration of 2,4dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) found in the shoots of wheat seedlings ranged from 1.4 to 10.9 mmol/ kg of fresh weight in a collection of Chilean cultivars (8), from 0.99 to 8.07 mmol/kg of fresh weight in a worldwide collection (7), and from 0.21 to 16.0 mmol/kg of fresh weight in a collection of wheat progenitors (14).…”

Section: Introductionmentioning

confidence: 99%

Benzoxazinoid Allelochemicals in Wheat: Distribution among Foliage, Roots, and Seeds

Villagrasa

Guillamón

Labandeira

et al. 2006

In this study, the distribution of eight allelochemicals among the foliage, roots, and seeds of different wheat varieties is reported for two different sampling campaigns, corresponding to two consecutive years. The determination of benzoxazinoid derivatives was performed by combining pressurized liquid extraction--solid-phase extraction followed by liquid chromatography--electrospray mass spectrometry. To the authors' knowledge, there are no previous works about the content of allelochemicals in seed tissue of germinated wheat seedlings. Allelochemicals found in seeds were detected at levels similar to those found in foliage and roots. The results showed that the type of metabolites detected depends strongly on the working up procedure of the plant material, as well as of plant growth stage. A general decrease of the total amount of allelochemical content in the plants was observed with plant age. There was a significant difference in the total amount of benzoxazinoid derivatives in the different wheat varieties analyzed.

“…Little information is available on the content of benzoxazinone derivatives in modern wheat cultivars. Niemeyer (8) analyzed the content of hydroxamic acids in various Triticum species and found the highest content in T. speltoides (16 mmol/kg of fresh weight) and the lowest in T. taushii (0.21 mmol/kg of fresh weight), whereas the modern wheat varieties contained intermediate levels of benzoxazinone derivatives (1.44-2.77 mmol/ kg of fresh weight). Copaja et al (9) analyzed a large number of Chilean and British wheat cultivars, mostly T. aestiVum, and found nearly a 10-fold difference in the levels of DIMBOA.…”

Section: Introductionmentioning

confidence: 99%

Quantification of Benzoxazinone Derivatives in Wheat (Triticum aestivum) Varieties Grown under Contrasting Conditions in Denmark

Mogensen¹,

Krongaard²,

Mathiassen³

et al. 2006

Three varieties of winter wheat (Triticum aestivum) were grown in both conventional and organic farming systems. The contents of the benzoxazinone derivatives 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), 2-beta-d-glucopyranosyloxy-4-hydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA-Glc), 6-methoxybenzoxazolin-2-one (MBOA), 2-hydroxy-7-methoxy-1,4-benzoxazin-3-one (HMBOA), benzoxazolin-2-one (BOA), and 2-hydroxy-1,4-benzoxazin-3-one (HBOA) were analyzed at five growth stages (BBCH 9-10, 12, 21, 31, and 53). Major differences were found between the varieties, with Stakado exhibiting the highest contents. In contrast, only minor and erratic differences were found between the two farming systems, suggesting that the inherent differences in the content of benzoxazinone derivatives of the varieties were not significantly affected by the use of pesticides and synthetic fertilizers. The concentration of benzoxazinone derivatives in the foliage was considerably higher at the early growth stages than later in the growing season, with DIMBOA being the most abundant of the benzoxazinone derivatives. An increase in the concentration was observed in early spring compared to late autumn, suggesting that plants synthesized benzoxazinone derivatives at the commencement of growth in early spring. The concentrations in the roots were considerably lower than in the foliage at the early growth stages but remained relatively constant over time, resulting in a higher concentration than in the foliage at the late growth stages. The results are discussed in relation to previous findings that predominantly originate from experiments done under controlled conditions in either growth cabinets or greenhouses.