QpmH esterase from cotton rhizosphere bacteria: A novel approach for degrading quizalofop-p-ethyl herbicide

Within the rhizosphere, a rich population of biocontrol bacteria serves as a valuable resource for the biodegradation of environmental herbicides. This study aimed to evaluate rhizospheric microorganisms for their potential to degrade Quizalofop-p-ethyl, a widely used herbicide to control annual and perennial weeds in a variety of crops. A bacterial strain, MJ-8, isolated from cotton rhizosphere soil, demonstrated significant degradation activity. Based on morphological characteristics and 16S rRNA sequencing, the strain was identified as Priestia megaterium. Strain MJ-8 achieved a degradation rate of 90.65 % for Quizalofop-p-ethyl. Genomic analysis and amino acid sequence alignment revealed a key gene, designated QpmH, encoding a 30 kDa protein with strong biodegradation activity. Heterologous expression of the QpmH gene confirmed its role in Quizalofop-p-ethyl degradation. Molecular docking studies and structural modeling further elucidated the enzymatic mechanisms, supported by the analysis of their degradation products. Additionally, when QpmH gene was introduced into rice plants through Agrobacterium-mediated transformation, the resultant transformant conferred resistance to Quizalofop-p-ethyl at the recommended application dose. These findings highlight Priestia megaterium strain MJ-8 as a promising biological agent for sustainable herbicide management and position the QpmH gene as a potential new target for developing herbicide-resistant crops.