CRISPR-induced knockouts reveal a dual role for the soybean NFR5α gene in symbiotic nitrogen fixation and root hair development.

Nitrogen fixation in soybeans, facilitated by symbiotic interactions with rhizobia, is a cornerstone of sustainable agriculture, reducing reliance on synthetic fertilizers. However, the efficiency of symbiotic nitrogen fixation (SNF) varies due to natural genetic variation in SNF-related genes. Our study underscores the pivotal role of the GmNFR5α gene not only in nodulation but also in root hair development, which is crucial for effective nutrient uptake and plant yield. Through detailed genetic analyses and clustered regularly interspaced short palindromic repeats (CRISPR)-based manipulations, we identified and characterized multiple knockout mutants, notably GmNFR5α-KO and combined GmNFR5α+GmROP6-KO, which exhibited significant reductions in root hair density and nodulation. These phenotypic changes correspond with the downregulation of key root hair development genes such as TTG, RHD1, RHD2, and KJK, establishing a clear link between GmNFR5α function and root hair formation. The potential of leveraging these genetic insights to improve nitrogen fixation in legumes and introduce SNF capabilities into cereal crops could revolutionize crop fertilization strategies, offering a sustainable solution to global agricultural challenges.