الكشف عن الطفرات المحتملة لجينات ACCase و ALS المقاومة

Detection of potential mutations of the herbicide-resistant ACCase and ALS genes in the genus Lolium

Abstract
Two field experiments were carried out in one of the fields of Al-Hindiyah District, Holy Karbala Governorate, during the winter agricultural season 2021-2022 in order to study potential mutations resistant to the action of some Lolium herbicides. The first experiment was designed according to the randomized complete block design (RCBD) with split plot arrangements and three replications, as the main plots included four types of herbicides: Chevalier, Pallas, Tobik, and Axial, with a comparison treatment (spraying with water only), while the sub plots included planting seeds of Lolium weed which collected from three Iraqi provinces: holy Karbala, Babil, and Wasit. As for the second experiment, it was carried out according to the randomized complete block design with one factor and three replications, as the factor included spraying 11 combinations of Chevalier, Pallas, Tobic, and Axial herbicides as well. spraying with water only . Wheat seeds of the Latifia cultivar were sown, and artificial infection was carried out by adding Lolium seeds. Some characteristics of growth, yield, and its components in wheat were measured, and the ALS and ACCase genes were detected and analyzed. The measurements were recorded for the weeds in two stages after 60 and 90 days.
The results of the study showed the following:
1- A number of mutations resistant to the action of the two herbicides, Tobic and Axial, were detected in the ACCase gene in the mRNA sequences of plants in holy Karbala, Wasit and Babel governorates, which are similar to the mutation found in resistant plants recorded globally, by substitution one nucleotide with another in codons 25, 29, 33, 167 and 209 from CGA, GAA, AAT, TTG, and ACA that code for amino acids to Arg, Glu, Asn, Leu, and Thr to CCA, GCA, CAT, ATG, and ATA that code for Pro, Ala, His, Met, and Ile, matched These mutations in the Iraqi weeds with the mutations recorded globally, also the results showed the presence of a missense mutation in codon 161 of the sequence of Wasit and Karbala plants resistant to the action of the herbicides, by substitution 2 nucleotides from the AAG codon, which encodes to Lys, to AGA, which encodes to Arg. Also, two frame shift mutations were observed in plants resistant to the action of the substitution in the provinces of Karbala and Wasit , The results of this gene were identical in Lolium temulentum bushes with Lolium rigidum bushes
2- A number of mutations were detected in the ALS gene of the mRNA sequences of plants of Karbala, Wasit and Babel governorates resistant to the action of herbicides Chevalier and Pallas, by substitution a nucleotide with another in codons 195 and 200 of AGC and AGT that encodes for the amino acid Ser to ACC and GGT that encodes for the two amino acids Thr and Gly, these mutations in the Iraqi weeds coincided with the mutations recorded globally. Also, two missense mutations were detected in codons 175 and 266 of the sequence of Wasit governorate plants, by substitution the codons GTC and CGC that encode for the amino acids Val and Arg with codons GGC and TGC that encode for the amino acids Gly and Cys sequentially, The results of this gene were identical in Lolium temulentum bushes with Lolium rigidum bushes, except for the presence of one silent mutation in codon number 150 GCT that encodes for the amino acid Ala, which changed to the codon GCC that encodes for the same amino acid in the bushes of Wasit province.
3- Chevalier was significantly superior to other herbicides (Pallas, Tobic, and Axial) in reducing Lolium weed characteristics such as plant height, chlorophyll index, weed density, control ratio, dry weight, and inhibition percentage.
4- There is a significant difference between the seeds of holy Karbala, Babylon and Wasit governorates in most of the traits under study such as Lolium weed height, chlorophyll index, number of tillers, Lolium weed dry weight after 60 and 90 days of spraying.
5- The Chevalier herbicide gave the highest inhibition rate to weeds whose seeds were taken from Babylon province attain5.72% , while the herbicides Axial gave the lowest inhibition rate to weeds whose seeds were taken from Wasit province attain 0.48 % after 90 days .
6-The combination Chevalier + Pallas + Tobik + Axial excelled in reducing most of the traits such as plant height, chlorophyll index, weed density and weed dry weight after 60 and 90 days of spraying, and the superiority of the traits was plant height, plant density, chlorophyll index, number of grains per spike, weight of 1000 grains, biological yield and grain yield of wheat crop. 98.90 cm, 308 plants M-2, 30.33, 32.33, 30.79g, 14.29 mg E-1, 5.12 mg E-1
7- The Chevalier + Pallas combination excelled by giving the highest number of tillers, number of spikes, weight of 1000 grains, biological yield and grain yield for wheat crop 391 cm, 368.67 spike m-2, 49.46 g, 17.55 mg e-1 and 6.25 mg g e-1, respectively.

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