Evolution of resistance to phytoene desaturase and protoporphyrinogen oxidase inhibitors – state of knowledge

Abstract

Two major classes of herbicides include inhibitors of protoporphyrinogen oxidase (PPO) and phytoene desaturase (PDS). Plants can evolve resistance to PPO and PDS inhibitors via several mechanisms that include physical changes, resulting in reduced uptake, physiological changes, resulting in compartmentalization or altered translocation, and biochemical changes, resulting in enhanced metabolic degradation or alterations of protein structures, leading to loss of sensitivity to the herbicides. This review discusses the involvement of some of these mechanisms in the various cases of resistance to PDS- and PPO-inhibiting herbicides, and highlights unique aspects of target-site resistance to these herbicides.

Impact of macrocidins, produced by Phoma macrostoma, on carotenoid profiles of plants

“…First of all, only one weed, hydrilla, has been reported to have developed target-site resistance to a PDS-targeting synthetic herbicide (Arias et al, 2006). As discussed by Dayan et al, (2014), evolution of target-site resistance to PDS inhibitors is improbable because only 10% of mutations that could lead to resistance in the PDS gene at the codon mutated in the resistant hydrilla can be achieved through a single nucleotide polymorphism (SNP). Furthermore, the codons mostly likely to be used in plants at the site of the resistance-conferring mutation in hydrilla require two SNPs within the same codon for resistance development.…”

The mechanism of diflufenican resistance and its inheritance in oriental mustard (Sisymbrium orientale L.) from Australia

“…However, oriental mustard seed requires light exposure for germination and is therefore unable to geminate if buried . Recently, populations of oriental mustard have been confirmed to be resistant to several herbicides including acetolactate synthase (ALS) inhibitors, synthetic auxins, carotenoid biosynthesis inhibitors and photosystem II inhibitors …”

“…Resistance to fluridone in hydrilla populations was conferred by one of three independent somatic mutations in the PDS gene at the arginine 304 (Arg304) codon . Resistance has also been confirmed in some other weed species such as eastern groundsel ( Senecio vernalis ) and oriental mustard ( Sisymbrium orientale ); however, the mechanism of resistance to the PDS‐inhibiting herbicides in these species is not known …”

“…Resistance to ALS‐inhibiting herbicides in oriental mustard in Australia was first reported in the 1990s . Since then, farmers have relied on PDS inhibitors and phenoxy herbicides to control this weed in crops.…”

Metabolic engineering of plants using a disarmed potyvirus vector

“…Since carotenoids are accessory pigments of photosynthesis and UV protectants of chlorophyll, interfering with carotenoid biosynthesis leads to drastic consequences for the plant. In fact, many herbicides target steps from carotenoid biosynthesis and in particular PDS (Dayan et al, 2014). The result of PDS-inhibition is the loss of carotenoid pigments, and the destruction of chlorophyll by photo-oxidation.…”