Resistance to paraquat in Mazus pumilus

Abstract

Mazus pumilus is an annual self-pollinating weed that is commonly found in arable land, vegetable gardens and roadsides. This weed harbours insects and pathogens that attack vegetables. The mechanism of resistance to paraquat of M. pumilus found in Ohita, Japan, was studied. Whole plant bioassays revealed that the resistant (R) biotypes were four to six times less susceptible than controls. Chlorophyll destruction of leaf discs by paraquat treatment in R biotypes was 4-20 times lower than those of susceptible (S) biotypes. Ferric reducing antioxidant power (FRAP) values in R biotypes were higher than those of S biotypes before and after paraquat treatments. The activity of superoxide dismutase (SOD) was also higher in R biotypes than those of S biotypes before and after treatment with paraquat, but the activities of ascorbate peroxidase (APX) and catalase (CAT) were not different between R and S biotypes. Change of ascorbate (AsA) contents before and after paraquat treatment was equivalent in both biotypes. These results indicate that the increased SOD activity and antioxidant capacity in R biotypes contribute to the resistance to paraquat of M. pumilus.

A Paraquat Tolerance Mutant in Rice (<i>Oryza sativa</i> L.) Is Controlled by Maternal Inheritance

“…Same results were reported in our previous report that no differences were detected in the uptake and transportation of paraquat after application in the three tested rice lines and the tolerance is due to the delay of cellular damage in the tolerance mutant [17]. These results supported that the organelles or cytoplasmic factors [7] [33] [34] of the tolerance lines may contribute to paraquat tolerance. Therefore, our results showed significant maternal effects in all the physiological traits detected.…”

“…Conyza bonariensis (L.) Corng. Lolium rigidum, Arctotheca calendula, Rehmannia glutinosa and Mazus pumilus have been reported in the world (http://www.weedscience.org/; [7]). In Arabidopsis, several paraquat resistant mutants including photoautotrophic salt tolerance 1 (pst1), radical-induced cell death1 (rcd1), paraquat resistant 1 (par1), paraquat resistant 2 (par2), pleiotropic drug resistance 11 (atpdr11) and resistant to methyl viologen 1 (rvm1) [8]- [13] have been identified and characterized.…”

Differences of endogenous polyamines and putative genes associated with paraquat resistance in goosegrass (Eleusine indica L.)

“…Paraquat resistance in plant cells is determined by the uptake, efflux, sequestration, detoxification, and catabolism of the reactive oxygen species (ROS) generated by paraquat [4]. Two hypotheses have been proposed for paraquat resistance in plants: One is an increase in the capability of plant cells to scavenge ROS, while the other is the ability of plant cells to sequester paraquat away from target sites in their chloroplasts [6]. Although there are numerous data available on paraquat resistance in response to rapidly increasing multi-resistance in weeds threats against crop production worldwide, no cases of target site paraquat-resistance have been identified for its difficult metabolism [2,7].…”

AtPQT11, a P450 enzyme, detoxifies paraquat via N-demethylation

“…The underlying mechanisms of paraquat resistance in weeds have been studied mostly at physiological and biochemical levels 3–6 . From these studies, two major mechanisms of paraquat resistance were suggested, including defects in paraquat translocation restricting the transport of paraquat to chloroplasts 4,7 , and enhanced antioxidation scavenging ROS more efficiently 8,9 . However, no genetic or molecular evidence for the proposed mechanisms has been revealed in weeds.…”