Effects of NtARF2 Knockdown on Growth, Development and Potassium Accumulation in Flue-cured Tobacco

To achieve efficient and targeted potassium improvement in tobacco, the CRISPR-Cas9 technology was used to knockout the NtARF2 gene in the flue-cured tobacco variety Jiucaiping2, thereby creating the NtARF2 knockout material (NtARF2-KO). The effects of NtARF2 gene knockout on agronomic traits, potassium content-related indicators, and economic traits of flue-cured tobacco were analyzed. The results showed that under normal potassium supply conditions, the proportion of potassium-deficient plants in the field at 85 days and 110 days after transplanting was significantly lower in NtARF2-KO than in Jiucaiping2. At 85 days after transplanting, the NtARF2-KO plants exhibited favorable growth and development, with significantly higher stem height and biomass than Jiucaiping2. There was no significant difference in photosynthetic efficiency between the leaves of NtARF2-KO and Jiucaiping2. The potassium content in leaves and total potassium accumulation per plant were significantly higher in NtARF2-KO than tin Jiucaiping2. The potassium content of C3F grade tobacco leaves after curing was significantly higher in NtARF2-KO than in Jiucaiping2, and the output value and medium-grade tobacco rate were significantly higher. Under low potassium conditions, the biomass and other traits of NtARF2-KO plants at 85 days after transplanting were significantly higher than those of Jiucaiping2. The proportion of potassium-deficient plants and SPAD value at 110 days after transplanting were significantly lower in NtARF2-KO than in Jiucaiping2. At 85 days after transplanting, the potassium content in the roots, stems, and leaves of NtARF2-KO and the total potassium accumulation of the whole plant were significantly higher than those of Jiucaiping2. There was no significant difference in yield between NtARF2-KO and Jiucaiping2, but the output value, high-grade tobacco rate, and medium-grade tobacco rates were significantly higher in NtARF2-KO. In conclusion, knocking out the NtARF2 gene in tobacco can increase plant potassium content and tolerance to low potassium, increase the output value of tobacco leaves, and has great application potential in the improvement of tobacco varieties for efficient potassium utilization.