The <i>ptxD</i> Gene Confers Rapeseed the Ability to Utilize Phosphite and a Competitive Advantage against Weeds

Abstract

Weed infestation has seriously affected the yield and quality of rapeseed, which is a globally significant oil crop. While the application of chemical herbicides in agriculture has greatly boosted agricultural efficiency and crop yield, it has also unfortunately led to escalating environmental pollution and the emergence of herbicide-resistant weeds. The ptxD gene, originating from bacteria, encodes the phosphite dehydrogenase enzyme that is responsible for converting phosphite (Phi) into orthophosphate (Pi). Phi remains unusable by plants and most microorganisms, but upon its conversion into Pi, it becomes a viable nutrient source for plants. This unique function of the ptxD gene offers promising avenues for the development of innovative weed control technologies. We tested the Phi tolerance of weeds and ptxD-expressing rapeseed (Brassica napus) through greenhouse experiments in rapeseed fields. The results revealed that a Phi concentration of 200 mg·kg of soil−1 inhibited the growth of all weeds in the rapeseed fields, while the ptxD-expressing rapeseed exhibited robust tolerance to this concentration of Phi. In field experiments, the application of 60 g·m−2 of Phi allowed the ptxD-expressing rapeseed to grow normally, while the weeds grew slowly due to phosphorus deficiency, resulting in the rapeseed having a strong competitive advantage over the weeds. The leaves of the transgenic rapeseed plants covered gaps in the field as they grew, further inhibiting weed growth and completely eliminating their harm due to shading effects. The combination of ptxD-expressing rapeseed and the application of phosphite offers a sustainable alternative to herbicides for weed management in rapeseed fields.

Keywords

• rapeseed
• weed control
• <i>ptxD</i> gene
• phosphite dehydrogenase
• herbicide