2,4-D and IAA Amino Acid Conjugates Show Distinct Metabolism in Arabidopsis

Abstract

The herbicide 2,4-D exhibits an auxinic activity and therefore can be used as a synthetic and traceable analog to study auxin-related responses. Here we identified that not only exogenous 2,4-D but also its amide-linked metabolite 2,4-D-Glu displayed an inhibitory effect on plant growth via the TIR1/AFB auxin-mediated signaling pathway. To further investigate 2,4-D metabolite conversion, identity and activity, we have developed a novel purification procedure based on the combination of ion exchange and immuno-specific sorbents combined with a sensitive liquid chromatography-mass spectrometry method. In 2,4-D treated samples, 2,4-D-Glu and 2,4-D-Asp were detected at 100-fold lower concentrations compared to 2,4-D levels, showing that 2,4-D can be metabolized in the plant. Moreover, 2,4-D-Asp and 2,4-D-Glu were identified as reversible forms of 2,4-D homeostasis that can be converted to free 2,4-D. This work paves the way to new studies of auxin action in plant development.

Modification of auxinic phenoxyalkanoic acid herbicides by the acyl acid amido synthetase GH3.15 from Arabidopsis

“…S2), which primarily use aspartate and glutamate, may help maintain inactive forms of 2,4-DB and contribute to tolerance (25)(26)(27)(28)(29)(30)(31)(32)(33). Amino acid conjugated forms of IAA have varied roles with the IAA-aspartate and IAAglutamate conjugates leading to hormone degradation and IAA-alanine and IAA-leucine conjugates providing storage forms of the auxin (31,38,39). The best-studied IAA and 2,4-D conjugates are those of aspartate and glutamate, which suggests that these molecules can be hydrolyzed back into free acid forms (39).…”

“…Amino acid conjugated forms of IAA have varied roles with the IAA-aspartate and IAAglutamate conjugates leading to hormone degradation and IAA-alanine and IAA-leucine conjugates providing storage forms of the auxin (31,38,39). The best-studied IAA and 2,4-D conjugates are those of aspartate and glutamate, which suggests that these molecules can be hydrolyzed back into free acid forms (39). With 2,4-D conjugates this contributes to maintaining the effect of the herbicide (39).…”

“…The best-studied IAA and 2,4-D conjugates are those of aspartate and glutamate, which suggests that these molecules can be hydrolyzed back into free acid forms (39). With 2,4-D conjugates this contributes to maintaining the effect of the herbicide (39). Currently, there is a lack of information on the metabolic fates of IBA and auxinic herbicides conjugated to other amino acids.…”

Multiplicación in vitro y embriogénesis somática de Perezia pinnatifida (Asteraceae) planta medicinal andina

“…3). En relación al efecto del 2,4-D, que es un compuesto ampliamente usado en la formación de callos (Elamvaluthi et al 2016, González et al 2006) porque funciona como auxina a bajas concentraciones; sin embargo contrariamente, en P. pinnatifida produjo marchites y muerte de las yemas a 1 -2 mg.L -1 y las condiciones evaluadas, porque esta hormona sintética es mas estable y podría tener efectos tóxicos sobre las dicotiledóneas (Eyer et al 2016). …”

Anise-cultured cells abolish 2,4-dichlorophenoxyacetic acid in culture medium

“…More than 32 kinds of 2,4-D-resistant plants are known (Quareshy et al 2018), and numerous approaches to counteract 2,4-D have been proposed, including sidechain degradation or extension, ring hydroxylation, sugar conjugation, amino acid conjugation, reduction of uptake or translocation, and specific efflux (Eyer et al 2016;Figueiredo et al 2018;Hamburg et al 2001;Ito and Gray 2006;Quareshy et al 2018;Rey-Caballero et al 2016). The mechanisms of metabolism and perception of 2,4-D in anise cells remain unclear.…”