Overexpression of LKF3H2 from Larix kaempferi Promotes Growth and Confers Resistance to Bursaphelenchus xylophilus in Arabidopsis

Pine wilt disease (PWD), caused by Bursaphelenchus xylophilus, poses a severe threat to coniferous forests worldwide, yet conventional control measures remain limited. Therefore, identifying resistance genes from resilient species such as Larix kaempferi has become crucial for developing genetic strategies to protect forests. The overexpression of LKF3H2 (LKF3H2-OE) from L. kaempferi in A. thaliana significantly enhanced both plant growth and resistance to B. xylophilu. Compared to wild-type (WT) plants, LKF3H2-OE transgenic lines exhibited a 61.4% increase in plant height, a 61.5% increase in silique number per plant, and accelerated bolting and flowering by 6 days and 5 days, respectively. Following nematode inoculation, the disease incidence in transgenic plants was 40%, significantly lower than that in WT plants (76%). This enhanced resistance was associated with the density- and time-dependent induction of LKF3H2 expression, which reached 2.04-fold under high inoculum pressure and 5.48-fold at 7 days post-inoculation. Furthermore, transgenic plants accumulated higher levels of defense-related metabolites, including flavonoids (up to 3.12 mg/g) and proline (up to 34.35 mg/g). These results demonstrate that LKF3H2 significantly improves nematode resistance by synergistically enhancing growth traits and activating disease-resistant metabolic pathways, highlighting its potential as a key genetic resource for breeding disease-resistant wood plants.