Inheritance and Physiological Basis for 2,4-D Resistance in Prickly Lettuce (Lactuca serriola L.)

Abstract

Experiments were conducted to determine the inheritance and physiological basis for resistance to the synthetic auxinic herbicide (2,4-dichlorophenoxy)acetic acid (2,4-D) in a prickly lettuce biotype. Inheritance of 2,4-D resistance in prickly lettuce is governed by a single codominant gene. Absorption and translocation were conducted using (14)C-2,4-D applied to 2,4-D-resistant and -susceptible biotypes. At 96 h after treatment (HAT), the resistant biotype absorbed less applied 2,4-D and retained more 2,4-D in the treated portion of the leaf compared to the susceptible biotype. The resistant biotype translocated less applied 2,4-D to leaves above the treated leaf and crown at 96 HAT compared to the susceptible biotype. No difference in the rate of metabolism of 2,4-D was observed between the two biotypes. Resistance to 2,4-D appears to originate from a reduced growth deregulatory and overstimulation response compared to the susceptible biotype, resulting in lower translocation of 2,4-D in the resistant prickly lettuce biotype.

Weed resistance to synthetic auxin herbicides

“…Inheritance of 2,4‐D resistance in prickly lettuce was governed by a single codominant gene . Biokinetic studies using ring‐labeled C‐2,4‐D were conducted to understand this mechanism of 2,4‐D resistance.…”

“…Growth was stimulated in the susceptible biotype during the first 4 days after treatment, but not in the resistant biotype . Beyond 4 days, growth of the susceptible biotype almost ceased, while the resistant biotype continued to grow.…”

2,4-D Past, Present, and Future: A Review

“…However, several papers have reported diverse NTSR mechanisms, including enhanced metabolism (Coupland 1994;Coupland et al 1990) and decreased translocation (Jugulam et al 2013). For example, a population of prickly lettuce (Lactuca serriola L.) resistant to 2,4-D displayed reduced uptake and translocation compared with a sensitive population, but rates of 2,4-D metabolism not different (Riar et al 2011). It is important to note, however, that these two mechanisms may be physiologically linked; i.e., rapid production of polar metabolites often leads to measurements of decreased translocation since polar metabolites and herbicide conjugates are typically less phloem mobile than parent compounds (Han et al 2013), most likely due to permanent sequestration in the vacuole via phase III transport and detoxification reactions (Devine and Hall 1990;Riechers et al 2010).…”

Reduced translocation in 2,4‐D‐resistant oriental mustard populations (Sisymbrium orientale L.) from Australia

“…Both resistant populations responded similarly, suggesting that this lack of translocation of the herbicide is the likely mechanism of resistance in this species. Previous studies in R. raphanistrum , G. tetrahit , P. rhoeas and L. serriola also found the 2,4‐D‐resistant biotypes had significantly lower herbicide translocation out of the treated leaves.…”

“…Light intensity was much lower for the R. raphanistrum study compared with our oriental mustard study (550 versus 90 µmol m −2 s −1 ), which may have influenced translocation of this herbicide. By contrast, 2,4‐D‐resistant L. serriola had similar amounts of translocation of 2,4‐D to that found in this study. Overall, these data suggest that there may be differences in 2,4‐D translocation patterns in 2,4‐D‐resistant plants between species and/or between growth conditions.…”