Somatic mutation‐mediated evolution of herbicide resistance in the nonindigenous invasive plant hydrilla (Hydrilla verticillata)

Abstract

Hydrilla (Hydrilla verticillata L.f. Royle) was introduced to the surface water of Florida in the 1950s and is today one of the most serious aquatic weed problems in the USA. As a result of concerns associated with the applications of pesticides to aquatic systems, fluridone is the only USEPA-approved chemical that provides systemic control of hydrilla. After a decrease in fluridone's efficacy at controlling hydrilla, 200 Florida water bodies were sampled to determine the extent of the problem and the biological basis for the reduced efficacy. Our studies revealed that hydrilla phenotypes with two- to six-fold higher fluridone resistance were present in 20 water bodies. Since fluridone is an inhibitor of the enzyme phytoene desaturase (PDS), the gene for PDS (pds) was cloned from herbicide-susceptible and -resistant hydrilla plants. We report for the first time in higher plants three independent herbicide-resistant hydrilla biotypes arising from the selection of somatic mutations at the arginine 304 codon of pds. The three PDS variants had specific activities similar to the wild-type enzyme but were two to five times less sensitive to fluridone. In vitro activity levels of the enzymes correlated with in vivo resistance of the corresponding biotypes. As hydrilla spread rapidly to lakes across the southern United States in the past, the expansion of resistant biotypes is likely to pose significant environmental challenges in the future.

Acetolactate Synthase–Inhibitor Resistance in Yellow Nutsedge (Cyperus esculentus): II—Physiognomy and Photoperiodic Response

“…On the other hand, minor genetic dissimilarity between the biotypes appears to show some degree of sexual reproduction through seeds. Although it has been shown that somatic mutagenesis can lead to herbicide resistance (Michel et al 2004) and might occur in tubers and lead to some level of genetic dissimilarity (Christian et al 2013), the levels observed in the present analysis certainly suggest the likelihood of sexual reproduction in the population makeup.…”

Genetic diversity in three invasive clonal aquatic species in New Zealand

“…This makes E. densa more adaptable. In invasive populations of the clonal aquatic species Hydrilla verticillata (L. f.) Royle, Albrecht et al [26] demonstrated that herbicide resistance evolved by somatic mutations.…”

One amino acid substitution in phytoene desaturase makes Chlorella zofingiensis resistant to norflurazon and enhances the biosynthesis of astaxanthin

“…This herbicide inhibits the activity of plant-type phytoene desaturase (PDS), a key enzyme involved in catalyzing the rate-limiting step of carotenoid biosynthesis (Chamovitz et al 1993). Mutants resistant to norXurazon may result from the increased amount of PDS gene product or from structural change of PDS that lowers its aYnity to the herbicide (Chamovitz et al 1991(Chamovitz et al , 1993Michel et al 2004). Therefore it may be possible to isolate C. zoWngiensis mutants with increased astaxanthin biosynthesis due to certain mutations in its PDS gene.…”