Comparative Analysis of 2,4-D Uptake, Translocation, and Metabolism in Non–AAD-1 Transformed and 2,4-D–Resistant Corn

Abstract

The Enlist™ traits provide 2,4-D resistance in several crops. Though corn is naturally tolerant to 2,4-D, the engineered trait conferred by the aryloxyalkanoate dioxygenase-1 (AAD-1) enzyme provides enhanced 2,4-D tolerance and confers resistance to the graminicide herbicide family, the aryloxyphenoxypropionates. The objectives of this research were 2-fold: (1) measure and compare uptake, translocation, and metabolism of 2,4-D in Enlist™ (E, +AAD1) and non–AAD-1 transformed (NT, −AAD1) isogenic corn hybrids; and (2) and investigate the effect of glyphosate and/or the Enlist™ adjuvant system (ADJ) on these factors and corn injury. Uptake of radiolabeled 2,4-D acid applied alone in corn was not altered by the addition of ADJ when tank mixed at 24 h after application (HAA). By contrast, uptake of radiolabeled 2,4-D was significantly lower (69%) compared with 2,4-D plus ADJ (89%) at 24 HAA with a premixed formulation of 2,4-D choline plus glyphosate-dimethylamine (Enlist Duo™ herbicide [EDH]). Translocation of 2,4-D between the two corn hybrids was not different. E corn metabolized more 2,4-D (100% of absorbed) than NT corn (84%), and glyphosate did not alter 2,4-D metabolism. Furthermore, the metabolism of 2,4-D to nonphytotoxic dichlorophenol (DCP) and subsequent DCP-derived metabolites formed in E corn was examined. Injury to E corn is not typically observed in the field; however, injury symptoms were clearly evident in E corn (within 24 HAA) when formulated acetochlor was tank mixed with EDH, which correlated with an increase in 2,4-D uptake during this time period. In summary, the lack of injury in E corn following EDH applied alone may be attributed to a relatively low amount of 2,4-D uptake and the combination of natural and engineered 2,4-D metabolic pathways.

Tank mixture of glyphosate with 2,4-D accentuates 2,4-D injury in glyphosate-resistant corn

“…Significance at p < 0.05 and p < 0.01 levels denoted by * and **, respectively. dioxygenase-1 (AAD-1) enzyme, which results in increased 2,4-D and aryloxyphenoxypropionate metabolism (Anonymous 2012;Ruen et al 2017;Skelton et al 2017). It has been suggested that the introduction of these new technologies will significantly increase 2,4-D use in corn and other crops (Peterson et al 2016).…”

Potential of plasma treatment as water reclamation process for irrigation

“…This is an unconventional approach to this type of tests, that can provide insights into the metabolic changes that do not produce visible modifications of the plants. Both 2,4-D plant intake and metabolites of this compound have been reported in the literature [38][39][40]. The dried plants were ground and a methanolic extract was prepared combining two methods described in literature [41,42].…”

Application time affects synthetic auxins herbicides in tank-mixture with paraquat on hairy fleabane control

“…This increase in ethylene biosynthesis is a physiological indicative that the herbicide has caused effects that could lead to the plant death (Song, 2013). Another important factor is the occurrence of adequate temperature and relative humidity in the morning (Table 1), providing greater absorption and translocation of 2,4-D (Peterson et al, 2016;Skelton et al, 2017).…”