Resistance mechanism of Leptochloa chinensis Nees to propanil

Abstract

The resistance mechanism of Leptochloa chinensis Nees to propanil was investigated, based on propanil metabolism, aryl acylamidase activity, and chlorophyll fluorescence at the 8 week growth stage of L. chinensis.The concentration of propanil in the leaf and culm extracts of the resistant (R) and susceptible (S) biotypes, as measured by gas chromatography (GC), was found to increase after propanil treatment.The concentration of propanil in the leaf and culm extracts of the S biotype at 72 h was 1.55 and 0.49 mg mL -1 , respectively. However, a lower concentration of propanil was observed in the R biotype, as compared to that in the S biotype.The residue of 3,4-dichloroaniline, as measured by GC, was detected only in the leaf extracts of the R biotype. In contrast, no residue of 3,4-dichloroaniline was observed in the S biotype.The level of aryl acylamidase in the leaf tissue extracts of the R biotype was~140% higher than that in the S biotype. The fluorescence studies showed that propanil inhibited the quantum efficiency of the photosystem II in both the R and S biotypes after 2 h of incubation time. However, when the leaf disks were transferred and incubated in deionized water for 48 h, the quantum efficiency increased in the R biotype but decreased in the S biotype. These results suggest that propanil metabolism, enhanced by aryl acylamidase activity, is the most likely factor contributing towards the mechanism of propanil resistance in L. chinensis plants at the 8 week growth stage.

A psbA mutation (Val219 to Ile) causes resistance to propanil and increased susceptibility to bentazon in Cyperus difformis

“…At 72 HAT, there were greater 3,4‐DCA concentrations in Cd‐PS tissue in the absence of carbaryl relative to Cd‐PR tissue that had received carbaryl. Cd‐PS tissue had higher 3,4‐DCA concentrations than Cd‐PR among treatments at 72 HAT, a major difference from previous studies in which propanil‐R weeds accumulated 3,4‐DCA concentrations several‐fold greater than S biotypes owing to metabolic resistance . Nonetheless, 3,4‐DCA levels in Cd‐PR might have been reduced by growth and expansion of propanil‐free tissue, which contributes to the dilution of both propanil and 3,4‐DCA in plant tissue, since the entire above‐ground tissue was harvested for this study.…”

“…GR 50 and LD 50 showed a 14‐ and 18‐fold increase in Cd‐PR resistance levels relative to Cd‐PS (Figs A and B respectively). The level of propanil resistance in C. difformis is substantially higher than the levels reported for propanil‐R Echinochloa colona , E. crus‐galli and Leptochloa chinensis . Levels of propanil resistance in these grasses ranged between 1.5‐fold and eightfold.…”

“…greatly resembles tolerance to propanil in rice and is attributed to enhanced propanil degradation by aryl acylamidase (AAA) (aryl acylamine amidohydrase, EC 3.5.1.13). The AAA enzyme catalyzes hydrolysis of propanil's amide bond, leading to rapid build‐up of the metabolite 3,4‐dichloroaniline (3,4‐DCA); propanil breakdown into 3,4‐DCA is either slow or absent in propanil‐susceptible (S) plants …”

Resistance to Propanil in Ricefield Bulrush (Schoenoplectus mucronatus) Is Conferred by apsbAMutation, Val219to Ile

“…This resistance level is greater than levels reported for propanil-R grass weeds, such as barnyardgrass [Echinochloa crus-galli (L.) Beauv. ], junglerice [Echinochloa colona (L.) Link], and Chinese sprangletop [Leptochloa chinensis (L.) Nees] (Fischer et al 1993;Juliano et al 2010;Sahid et al 2011), which had 1.5-to 8-fold increased levels of resistance. Resistance in the aforementioned weeds was later attributed to enhanced propanil metabolism, suggesting propanil resistance in ricefield bulrush might be conferred by another mechanism.…”

Herbicide‐resistant weeds in the Philippines: Status and resistance mechanisms

“…Based on the dose-response assays that were conducted by Juliano et al (2010), it is likely that the resistance mechanism of the biotypes that were observed in the Philippines also was related to the enhanced metabolism of the propanil herbicide, including when used in combination with butachlor. Similarly, Sahid et al (2011) reported that enhanced metabolism due to increased arylacylamidase activity is also the resistance mechanism in propanil-resistant Leptochloa chinensis, which appeared in Malaysia in 2011.…”