Pine wilt disease (PWD) is the most destructive disease threatening pine worldwide. The disease is mainly caused by the pine wood nematode, Bursaphelenchus xylophilus, which is vectored by pine sawyer longhorn‐beetles, Monochamus spp. This study aimed to select resistance‐inducing pine endophytic bacteria for management of PWD. To set up a defence‐related genes expression pattern for screening, four chemical inducers (salicylic acid, γ‐aminobutyric acid (GABA), β‐aminobutyric acid and α‐aminobutyric acid) were tested in vitro on pine calli and in vivo on pine seedlings. Treatment with GABA had the greatest reduction in PWD severity on pine seedlings. The pattern of defence‐related gene expression in calli treated with GABA was used to select potential resistance‐inducing bacterial strains. In addition, 92 bacterial strains were isolated from pine tree needles and stems and were tested for expression of defence‐related genes in pine calli in vitro. Among the tested strains, 13 showed a similar pattern to GABA treatment in at least four tested defence‐related genes and were selected for the seedling assay. From the seedling assay, three bacterial strains (16YSM‐E48, 16YSM‐P180 and 16YSM‐P39) showed significant reduction in PWD severity compared to the untreated control. Moreover, among the selected strains, cell‐free culture supernatant of strain 16YSM‐P180 significantly reduced PWD severity in inoculated pine seedlings. The selected strains were identified based on the 16S rRNA sequence as Pseudomonas putida 16YSM‐E48, Curtobacterium pusillum 16YSM‐P180 and Stenotrophomonas rhizophila 16YSM‐P39. These selected strains are suggested as potential alternatives for management of PWD by induction of systemic resistance.

PWN inoculation. In conclusion, foliar spraying with either B. thuringiensis JCK-1233 culture suspension or DPKs could induce resistance in pine seedlings, thereby alleviating the serious damage by PWD. Taken together, this study supports aerial spraying with eco-friendly biotic or abiotic agents as a valuable strategy that may mark an epoch for the control of PWD in pine forests.

Ge-doped tetrahedrites Cu12Sb4-yGeyS13 (y = 0.1–0.4) were prepared using mechanical alloying and hot pressing. An X-ray diffraction analysis after mechanical alloying showed a single tetrahedrite phase without secondary phases. The tetrahedrite phase was stable after hot pressing at 723 K under 70 MPa. As the Ge content increased, the lattice constant decreased from 1.0343 to 1.0334 nm, which confirms that Ge was successfully substituted at the Sb sites. Ge-doped tetrahedrites exhibited p-type semiconductor characteristics. When Ge4+ was substituted for Sb3+, additional electrons were generated. Thus, the electrical conductivity decreased and the Seebeck coefficient increased due to the decrease in carrier (hole) concentration. For the Ge-doped specimen with y = 0.1, a maximum power factor of 0.87 mWm-1K-2 was obtained at 723 K. As the Ge content increased, the power factor decreased. However, as the Ge content increased, the electronic and lattice thermal conductivities decreased. Therefore, the substitutions of Ge at the Sb sites intensified both ionization impurity scattering and phonon scattering, resulting in very low thermal conductivities of 0.4–1.0 Wm-1K-1 at 323–723 K for y = 0.1–0.4. As a result, the highest dimensionless figure of merit ZT = 0.74 was obtained at 723 K for Cu12Sb3.8Ge0.2S13.