Multiple Resistance Evolution in Bipyridylium-Resistant Epilobium ciliatum After Recurrent Selection

Abstract

The use of herbicides with different modes of action is the primary strategy used to control weeds possessing resistance to a single mechanism of action (MOA). However, this practice can lead to selection for generalist resistance mechanisms and may cause resistance to all MOAs. In this research, we characterized the resistance to diquat/paraquat (bipyridiliums) in an Epilobium ciliatum biotype (R1) collected in an olive orchard from Chile, where alternatives herbicides (2,4-D, glyphosate, glufosinate, flazasulfuron and pyraflufen-ethyl) with different MOAs were used, but they have also showed failure in controlling this species. Because the resistance/susceptibility patterns of the R1 biotype to glufosinate, 2,4-D and pyraflufen-ethyl were not clear, a recurrent resistance selection was carried out in field and greenhouse using these herbicides on R1 plants for three generations (R2 biotype). One biotype that was never treated with herbicides (S) was included as control. Results indicated that the S biotype was controlled at the field dose of all herbicides tested. The biotype R1 exhibited resistance to diquat, paraquat and flazasulfuron and natural tolerance to glyphosate. The R2 biotype displayed resistance to glufosinate, 2,4-D and pyraflufen-ethyl with LD50 (herbicide dose to kill 50% of plants) values higher than field doses in all assays. Physiological and biochemical studies determined the resistance to diquat of the R1 biotype, which was due to impaired translocation. The resistance to flazasulfuron in the R1 and R2 biotypes was confirmed by the low sensitivity of the acetolactate synthase (ALS) activity compared to the S biotype. The similar accumulation of shikimate in treated S, R1, and R2 plants with glyphosate supported the existence of innate tolerance to this herbicide in E. ciliatum. Resistance to glufosinate, 2,4-D and pyraflufen-ethyl in the R2 biotype, acquired after recurrent selection, was determined by low sensitivity of the glutamine synthetase, low accumulation of ethylene and protoporphyrinogen IX oxidase, respectively, in comparison to the S biotype. Epilobium ciliatum from Chilean olive orchards had resistance to only two MAOs (photosystem I and ALS inhibitors), but resistance to five MOAs could occur in the next cropping seasons, if alternatives to weed management, other than herbicides, are not included.

Evolving Multiple Resistance to EPSPS, GS, ALS, PSI, PPO, and Synthetic Auxin Herbicides in Dominican Republic Parthenium hysterophorus Populations. A Physiological and Biochemical Study

“…This result indicates that glufosinate resistance in P. hysterophorus is likely to be target-site based, although this hypothesis needs to be investigated. Similar results were found for Epilobium ciliatum in Chilean olive orchards [38]. Avila-Garcia and Mallory-Smith [59] and Jalaludin et al [60] noted a similar sensitivity of the GS enzyme between susceptible and resistant populations, indicating that glufosinate resistance is not conferred by the target site.…”

“…The response of the glutamine synthetase enzyme (S) to glufosinate was determined using extracts of crude protein isolated from the R and S populations of P. hysterophorus following the methodology described by Tahmasebi et al [38]. The following glufosinate concentrations were applied: 0, 15.6, 31.25, 62.5, 125, 250, 500, 1000, 2000, and 4000 µM.…”

“…The acetolactate synthase (ALS) activity was determined following the methodology described by Hatami et al [39] and Tahmasebi et al [38], using 3 g of young leaf tissue per each population. The crude extract of the ALS enzyme was used to measure the enzyme activity at increasing concentrations (0, 0.1, 1, 10, 100, 1000, and 10,000 µM) of flazasulfuron.…”

“…The solution applied contained 14 C-paraquat, providing 0.834 kBq µL −1 at a final concentration of 100 g ia ha −1 of paraquat in 300 L. One microliter per plant of solution was applied on the adaxial surface of the second youngest fully expanded leaf. After treatment, the plants were maintained in the growth chamber for 12 h in the dark before being exposed to light [38,40].…”

“…After 24 h of treatment, 400 g of leaf tissue was placed in a 10 mL syringe with 1 mL of distilled water and then sealed [42]. The syringes were placed in a dark incubator at 27 • C for 4 h. The ethylene (C 2 H 4 ) in 1 mL of the gas at the top of the syringe was analyzed by gas chromatography [38,43]. The C 2 H 4 content was expressed as nanoliters per gram of fresh weight per hour.…”