The Bursaphelenchus xylophilus effector BxML1 targets the cyclophilin protein (CyP) to promote parasitism and virulence in pine

Abstract

Background Bursaphelenchus xylophilus is the causal agent of pine wilt disease (PWD) that has caused enormous ecological and economic losses in China. The mechanism in the interaction between nematodes and pine remains unclear. Plant parasitic nematodes (PPNs) secrete effectors into host plant tissues. However, it is poorly studied that role of effector in the infection of pine wood nematode (PWN). Results We cloned, characterized and functionally validated the B. xylophilus effector BxML1, containing an MD-2-related lipid-recognition (ML) domain. This protein inhibits immune responses triggered by the molecular pattern BxCDP1 of B. xylophilus. An insitu hybridization assay demonstrated that BxML1 was expressed mainly in the dorsal glands and intestine of B. xylophilus. Subcellular localization analysis showed the presence of BxML1 in the cytoplasm and nucleus. Furthermore, number of B. xylophilus and morbidity of pine were significantly reduced in Pinus thunbergii infected with B. xylophilus when BxML was silenced. Using yeast two-hybrid (Y2H) and coimmunoprecipitation (CoIP) assays, we found that the BxML1 interacts with cyclophilin protein PtCyP1 in P. thunbergii. Conclusions This study illustrated that BxML1 plays a critical role in the B. xylophilus–plant interaction and virulence of B. xylophilus.

Design, Synthesis, Nematicidal, and Fungicidal Activities of Novel Azo and Azoxy Compounds

“…In summary, 20 azoxy compounds (Ia−IVc) were synthesized and characterized through 1 H NMR, 13 C NMR, and HRMS. The bioassay against B. xylophilus indicated that some compounds showed excellent nematicidal activities where Ia, IIa, IIc, IId, and IVa displayed much better inhibition than avermectin with the LC 50 of 1.37, 1.12, 0.889, 1.56, and 1.10 μg•mL −1 , respectively.…”

“…During the synthesis procedure, the total yield of some compounds like IIe, IIIc, IIIe, and IIIf were lower than 10% for a kind of muddy byproduct. All of the target compounds were identified and characterized by 1 H NMR, 13 C NMR, and HRMS analysis. In the 1 H NMR spectra of compounds IIb−IIe and IIIa−IIIb, the methyl on the benzene ring generally appears around δ 2.43−2.45, while the symmetrical hydrogens on the benzene ring appear in pairs at δ 7.85−8.09 and δ 7.07−7.33.…”

“…xylophilus are usually Maritime Pine (Pinus pinaster Aiton), Austrian pine (Pinus nigra), Radiata pine (Pinus radiata D. Don), red pine (Pinus densiflora), black pine (Pinus thunbergii Parlatore), and Korean pine (Pinus koraiensis Siebold et Zuccarini). ,, Since B. xylophilus was first reported in 1982 in Nanjing, it has been spread nationwide in China and 17,160 km 2 trees have been infected that has caused significant economic damage. − …”

“…isomerism of the azoxy group especially in Ia and IIa that should be verified in the future. In the13 C NMR spectra of compounds IIb−IIe and IIIa−IIIb, the carbon on the carbonyl group linked to the azo group often transmits to the chemical shift of δ 157.72−161.81, and the peaks of symmetric carbon on the benzene ring always appear in pairs at δ 129.59−130.27 and 122.44−129.83. The cyano group on the benzene ring of compounds Id, Ie, IIIe, IIIf, and IIIg appears at δ 116.51− 116.84.…”

A Bursaphelenchus xylophilus effector BxICD1 inducing plant cell death, concurrently contributes to nematode virulence and migration

“…In recent years, many PPN effectors with PCD-inhibiting properties have been identified, especially from sedentary endoparasitic phytonematodes, e.g., root-knot nematodes and cyst nematodes ( Postma et al., 2012 ; Chen et al., 2017 ; Song et al., 2021 ; Chen et al., 2022 ). In the migratory endoparasitic phytonematode B. xylophilus , six effectors were also found to inhibit PCD ( Hu et al., 2021 ; Wen et al., 2021 , Wen et al., 2022 ; Zhang et al., 2022 ; Hu et al., 2022a ; Qiu et al., 2023 ). Interestingly, five effectors from B. xylophilus were confirmed to have the ability to activate PCD.…”