Generation of novel phosphite-mediated weed control system for Brassica napus by expressing PtxDQ from Ralstonia sp.4506

Abstract Weeds are managed by the herbicides in modern agriculture. However, the herbicide control options are rapidly diminishing due to the recent increased in the number of herbicide-resistant weeds in fields, which affect the sustainable development of agriculture in the future. Plants could absorb phosphite (Phi) through the Pi transporters, but the Phi cannot be metabolized and used as phosphorus (P) fertilizers for crops, which leads to the plant growth inhibition. Previously, a ptxD gene isolated from Ralstonia sp.4506, and a mutagenesis of the Tyr139 to Gln (Y139Q) enhanced activity of PtxD. To evaluate the efficacious of a phosphite-based weed control system in Brassica napus, we generated transgenic B. napus plants with a codon-optimized ptxD (Y139Q, ptxDQ) gene. Ectopic expression of ptxDQ gain an ability to convert Phi into orthophosphate (Pi), leading to improved plant growth in the presence of Phi. When P is supplied in the form of Phi, ptxDQ-expressing B. napus plants outcompete Setaria glauca, in artificial substrates. Additionally, Pi-starvation induced genes were suppressed in ptxDQ transgenic lines by suppling Phi. Overall, the ptxDQ/Phi system provide an effective alternative to suppressing the growth of weeds while providing adequate Pi nutrition to the crops, which in turn will improve the sustainability of agriculture.