Chlorsulfuron inhibition of phloem translocation in chlorsulfuron-resistant and -susceptible Arabidopsis thaliana
1993
Hall, L.M. | Devine, M.D.
The herbicide chlorsulfuron is not translocated readily in plants because of an inhibitory effect on phloem translocation. More chlorsulfuron was translocated in a chlorsulfuron-resistant (R) biotype of Arabidopsis thaliana than in a susceptible (S) biotype, indicating that the effect on translocation is secondary to inhibition of ALS, the primary site of action of the herbicide. The R biotype did not different from the S biotype in its ability, to translocate exogenously applied sucrose: however, translocation of exogenously applied sucrose following chlorsulfuron treatment was greater in the R biotype than in the S biotype. Chlorsulfuron pretreatment inhibited rapid sucrose uptake into leaf discs by 41% in the S biotype but by only 17% in the R biotype. This result suggests that chlorsulfuron inhibits phloem transport by restricting sucrose uptake into the phloem. Purified plasma membrane preparations extracted from the two biotypes following chlorsulfuron treatment did not differ in H+ -ATPase activity or total plasmalemma protein content. Possible alternative mechanisms by which chlorsulfuron may inhibit phloem transport are discussed.
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