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Different defense pathways in plants evolved in reaction to pathogens. The main aim of this study was to investigate the mechanism of action of glyphosate in resistance induction to bacterial phytopathogens. To do so, glyphosate at an optimal concentration of 1.8 mg / l was used on transgenic potato, to induce resistance to two strains of pathogenic bacteria (21A of Pectobacterium atrosepticum and ENA49 of Dickeya dadantii). It was been shown that plant defense responses to pathogens can be stimulated by treatment plants at an optimal concentration of glyphosate. Transgenic potato leaves infected with potato pathogenic bacteria, and then treated with glyphosate showed a high level of expression of pathogenesis-related genes (PR-2, PR-3, PR-5), especially PR-2 gene and defense response genes (HSR-203j, HIN1), especially HSR-203j gene. The expression of PR-2 gene in leaves infected with these two bacteria were 1.5 and 2.9 times, for PR-3 gene 1.7 and 1.7 times, for PR-5 gene to 1.3 and 1.5 times and expression of HSR-203J gene to 2.5 and 2.4 times and - HIN1 gene to 1.7 and 1.7 times, with Dickeya dadantii and Pectobacterium atrosepticum infection, respectively. The expression of these genes in control samples didn’t significantly change. The results showed that there was a significant difference between the expression of genes in the experimental and control samples (plants treated by glyphosate compared to untreated plants). The results showed that the treatment of plants by glyphosate can induce a systemic acquired resistance to phytopathogens by inducing proteins and defense response genes.

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The alternative use of non-selective herbicides in different years will reduce the possibility of weeds resistance to herbicide by avoiding the crops constant exposure to herbicide selection pressure. The photoperiod-sensitive genic male sterile (PGMS) rice with herbicide resistance will be convenient to the mechanization of hybrid seed production and weed control. In order to develop double herbicide tolerant transgenic PGMS rice, the optimized Epspsgene and the Bar gene were jointly introduced into 7001S, a japonica PGMS rice, by Agrobacterium-mediated transformation. The coding sequence of Epsps gene was optimized based on the codon usage of rice genes and the function of optimized Epspsgene was validated by real-time PCR analysis, enzyme-linked immunosorbent assay of EPSPS protein, and herbicide resistant assay in the obtained independent transformants. The highest relative expression level of EPSPS protein in leaf reached 9.02% of the total soluble proteins. The transformants of T₂ generation withstood at least 3.332 g glyphosate /m² at seedling stage, which was 2.7 times higher than that reported by Monsanto Company. The transformants harboring the optimized Epsps gene and Bar gene were also resistant to glyphosate and glufosinate simultaneously at seedling stage; the resistant dosages were 0.375 g glufosinate m^-2 and 0.833 g glyphosate m^-2.

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Manipulation of different genes in crop plants to get desirable characters has become an important tool of plant biotechnology. In the current study, cotton variety MNH-786 was modified for its characteristics to show resistance against lepidopteran insects and herbicide by transformation of Cry1Ac+Cry2A and GTGene cloned in a different cassette under 35S Promoter. Mature embryos of cotton MNH-786 were injured by a sharp blade at the shoot apex and infected with the Agrobacterim tumefaciens harboring transgene constructs. Transformed cotton plants were successfully acclimatized in pots and later the green house. Gene specific PCR and ELISA confirmed the transgene presence and its protein expression which was considerably higher in transformed plants. Overall transformation efficiency was 1.05%. All larvae of Helicoverpa armigera feeding on transgenic cotton leaves of T₀ were found dead as compared to the control ones feeding on leaves from non-transgenic cotton. Transgenic plants also survived a glyphosate spray dose of 1,900 ml acre^-1 as compared to herbs/weeds growing along with them, which burned completely five days post glyphosate application.

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Glyphosate resistance has been found in two populations of Italian ryegrass (Lolium multiflorum) following many years of glyphosate application in New Zealand vineyards. Dose-response experiments showed that both glyphosate-resistant Italian ryegrass populations had 10-fold levels of resistance to glyphosate compared to a susceptible population. Possible mechanisms of glyphosate resistance target site mutation at position Pro-106 of 5-enolpyruvyl-shikimate-3-phosphate synthase gene and alterations in glyphosate absorption/translocation in these populations were investigated. Genotyping assays demonstrated that there was no point mutation at Codon 106 of the 5-enolpyruvyl-shikimate-3-phosphate synthase gene in either of the resistant populations. Glyphosate-resistant and susceptible populations did not differ in ¹⁴C-glyphosate absorption. However, in both resistant populations, much more of the absorbed ¹⁴C-glyphosate was retained in the treated leaf than occurred in the susceptible population. Significantly more ¹⁴C-glyphosate was found in the pseudostem region of susceptible plants than resistant plants. Based on these results, it was suggested that alterations in glyphosate translocation patterns plays a major role in glyphosate resistance for Italian ryegrass populations from these New Zealand vineyards.

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Studies on determination of the effect of herbicides on survivability of Plant Growth Promoting Bacteria have a strategic usefulness in determination of plant health and the fate of applied agrochemicals in agroecosystem. Antimicrobial potential was assessed using estimation of a minimum inhibitory concentration of the Roundup 360 SL against Pseudomonas sp. A quantitative analysis of bacteria was performed, and the tendency of physicochemical changes in the mineral medium was evaluated during long-term exposure to the herbicide. Furthermore, the antagonism of the SP0113 strain against F. culmorum and F. oxysporum under stress conditions caused by Roundup® 360 SL was verified. It was demonstrated that use of the undiluted and 2.6-fold diluted product resulted in the inhibition of growth of the investigated strain. Pseudomonas sp. SP0113 showed survivability and resistance to near recommended dose concentration of Roundup® 360 SL. The possibility of bacterial development on the Tryptic Soy Agar (TSA) medium at contact concentrations of 14.4 and 5.4 mg mL^-1, as per the diluents quantity declared by the producer, indicates the role of cofactors such as: adiuvant or pH, redox potential (mV) or salinity. They comprise pH change, oxidation and salinity that may be due to the reaction of the active substance of the herbicide with mineral nutrient ingredients. The high salinity of environment, as a result of the reactions with the ingredients contained in the medium, is characteristic for concentrations higher than those recommended in practice. Furthermore, it was found that glyphosate limits the growth of fungi of the Fusarium genus, which support plant protection using strain SP0113.