Abstract
The urgent need to replace petroleum-derived materials with sustainable alternatives drives innovation at the nexus of plant biotechnology and materials science. Here, we engineered Populus alba × P. glandulosa '84 K' through CRISPR-Cas9-mediated knockout of PagGLR2.8, a glutamate receptor gene regulating vascular development, to investigate its role in fibre biosynthesis and composite performance. Knockout of PagGLR2.8 improved the quality of poplar fibre by altering the structure and development mode of poplar vascular tissue. Our study established the relationship between fibre quantity and structure and the performance of polylactic acid (PLA) composites. The mechanical and fire-resistance properties of these transgenic plant fibres/PLA composites significantly outperformed those of pure PLA, demonstrating the potential of phloem fibres to reinforce toughened composites. Notably, we also evaluated flammability and dripping behaviours, with findings indicating that our optimised fibre/PLA composites exhibit superior strengths, modulus, fire resistance, and anti-dripping, surpassing those of PLA. This research unveils a groundbreaking approach to regulating composite properties through genetic manipulation and highlights the promising potential of plant-derived materials in enriching forest resources and advancing the sustainable utilisation of poplar fibres and polymers.