Pathophysiology and transcriptomic analysis of Picea koraiensis inoculated by bark beetle-vectored fungus Ophiostoma bicolor

Ophiostomatoid fungi exhibit a complex relationship with bark beetles; exhausting of host tree defenses is traditionally regarded as one of the key benefits provided to beetle vectors. Ophiostoma bicolor is one of the dominant species of the mycobiota associated with Ips genus bark beetles which infect the spruce trees across the Eurasian continent. Host spruce trees resist fungal invasion through structural and inducible defenses, but the underlying mechanisms at the molecular level, particularly with respect to the interaction between bark beetle-associated fungi and host trees, remain unclear. The aim of this study was to observe the pathological physiology and molecular changes in Picea koraiensis seedlings after artificial inoculation with O. bicolor strains (TS, BH, QH, MX, and LWQ). This study showed that O. bicolor was a weakly virulent pathogen of spruce, and that the virulent of the five O. bicolor strains showed differentiation. All O. bicolor strains could induce monoterpenoid release. A positive correlation between fungal virulence and release of monoterpenoids was observed. Furthermore, the release rate of monoterpenoids peaked at 4 days post-inoculation (dpi) and then decreased from 4 to 90 dpi. Transcriptomic analysis at 4 dpi showed that many plant-pathogen interaction processes and mitogen-activated protein kinase (MAPK) metabolic processes were activated. The expression of monoterpenoid precursor synthesis genes and diterpenoid synthesis genes was upregulated, indicating that gene expression regulated the release rate of monoterpenoids at 4 dpi. The enriched pathways may reveal the immune response mechanism of spruce to ophiostomatoid fungi. The dominant O. bicolor possibly induces the host defense rather than defense depletion, which is likely the pattern conducted by the pioneers of beetle-associated mycobiota, such as Endoconidiophora spp.. Overall, these results facilitate a better understanding of the interaction mechanism between the dominant association of beetles and the host at the molecular level

Diversity of fungi associated with Monochamus alternatus larval habitats in Bursaphelenchus xylophilus-infected Pinus massoniana and identification of two new ophiostomatalean species (Ascomycota, Ophiostomatales)

Bursaphelenchus xylophilus, a pathogenic pine wood nematode (PWN), is responsible for pine wilt disease (PWD), which has caused significant economic and ecological damage worldwide, particularly in East Asia. Multiple biological factors, such as the beetle vector Monochamus, symbiotic bacteria and associated fungi, are involved in the disease infection cycle. This study isolated and identified the fungal communities of Monochamus alternatus larval galleries and pupal chambers from different instars through field investigation, morphological observation and multi-locus DNA sequence analyses in Zhejiang Province, China. A total of 255 and 454 fungal strains were isolated from M. alternatus galleries and pupal chambers infected with PWN, from the 2nd–3rd and 4th–5th instar larvae, respectively. A total of 18 species of fungi were identified, 14 species were isolated from the 2nd–3rd instar larval galleries and six species from the galleries and pupal chambers of the 4th–5th instar larvae. Amongst them were six species belonging to four genera of ophiostomatalean fungi, including two novel species, Graphilbum xianjuensis sp. nov. and Ophiostoma taizhouense sp. nov. and four known species, Ceratocystiopsis weihaiensis, Ophiostoma ips, Sporothrix zhejiangensis and S. macroconidia. The findings revealed that the fungal diversity and abundance of the 2nd–3rd instar larvae differed markedly from those of the 4th–5th instar larvae. This difference could be the result of fungal succession. This study provides a thorough understanding of the fungi associated with PWD and lays the groundwork for future research

Chirality detection of amino acid enantiomers by organic electrochemical transistor

Chiral recognition of alpha-amino acids is attracting increasing interest due to the importance of alpha-amino acids in protein metabolism as well as in food products and pharmaceuticals. Organic electrochemical transistors (OECTs) with gate electrodes modified with molecularly imprinted polymer (MIP) films were fabricated and successfully used as highly selective and sensitive chiral recognition biosensors for D/L-tryptophan (D/L-Trp) and D/L-tyrosine (D/L-Tyr). The MIP films, which can specifically recognize and has an electrocatalytic effect on the oxidation of Trp and Tyr, together with the amplification function of an OECT, provide a highly sensitive and selective OECT biosensor. The sensor showed a linear response range for L-Trp and t-Tyr from 300 nM to 10 mu M with a sensitivity of 3.19 and 3.64 mu A/mu M, respectivity. And the detection limit for L-Trp and L-Tyr is of 2 nM and 30 nM (S/N > 3). The selectivity factors of L-Trp, D-Trp, L-Tyr and D-Tyr to their enantiomers are 11.6, 3.5, 14.5 and 2.6, respectively. This method can pave the way for widespread applications of OECT-based sensors in chiral material identification.114sciescopu