POTENTIAL MUTATION IN PDS GENE THAT CAUSES HERBICIDE RESISTANCE IN WILD RADISH GROWS WITH WHEAT CROP

Abstract

A field experiment set out during the winter of 2022–2023 availed one of the Holy Kerbala Governorate's agricultural experimental fields. The study aimed to evaluate the efficacy of some herbicides in controlling the wild radish weeds accompanying the wheat crop, as well as, diagnosing genetic mutations in the PDS gene responsible for resistance to herbicides in wild radish. The experiment employed a randomized complete block design (RCBD) with a split-plot arrangement and three replications. The main plots included five groups of wild radish seeds taken from five Iraqi Governorates, i.e., Najaf, Kerbala, Babel, Diwaniyah, and Wasit. The subplots contained four herbicides: Navigator, Tatsteler, Mark zone, and Decimate, in addition to the treatment of spraying with water only. Wild radish seeds serve for artificially infecting wheat seeds after field preparation. The study also measured wheat yield components, with the weeds appraised twice after 60 and 90 days of management. Genomic alterations in the PDS gene caused herbicide resistance in wild radish. The global herbicide-resistant cultivar has two missense mutations in codons 69 and 330 (TGT → TAT and CGT → GGT), encoding for Cys → Tyr and Arg → Gly. These alterations were identical in all weeds studied, but some Governorates had new mutations, such as, in the seeds of the Babylon Governorate's weed. The evaluation of the efficiency of chemical pesticides comes after 60 and 90 days. Wild radish seeds in the targeted Governorates differed in all features. The herbicides Navigator and Decimate are vital in giving the best percentages of control and inhibition in wild radish weeds. Chemical herbicides have enhanced wheat production by eradicating weeds, specifically difficult ones. Genetic changes in wild radish weeds in wheat crops make some chemical herbicides less effective. Herbicide-resistant radish weed seeds are genetically mutated. Thus, herbicides can target gene variants and be diversified to prevent weed resistance.