PtoJAZ gene family analysis in Poplar 741 and insect resistance identification for PtoJAZ10

Jasmonate ZIM-domain (JAZ) proteins are core components of the jasmonic acid signaling pathway, playing key roles in plant growth, development, and stress responses. In this study, we identified 39 JAZ family members in poplar 741 and designated them PtoJAZ1 to PtoJAZ39 according to their chromosomal order. Phylogenetic analysis grouped them into six distinct subclades, with most members harboring conserved C-terminal motifs, including motifs 1–3. Collinearity and promoter analyses revealed a close evolutionary relationship with the Eucalyptus grandis JAZ family, alongside an enrichment of hormone- and stress-responsive cis-elements. PtoJAZ10 was strongly transcriptionally induced by methyl jasmonate (MeJA), abscisic acid (ABA), and Helicoverpa armigera feeding, with its expression increasing 17.5-fold after 24 h of herbivory, prompting its selection for further functional study. Subcellular localization confirmed that PtoJAZ10 is a nuclear protein. Overexpression of PtoJAZ10 in tobacco significantly reduced leaf consumption by H. armigera and impaired larval growth. Upon insect challenge, transgenic plants displayed markedly higher endogenous levels of JA and ABA, increased lignin accumulation, and enhanced activities of the antioxidant enzymes SOD, POD, and CAT, as well as phenylalanine ammonia-lyase (PAL), while showing lower malondialdehyde (MDA) content compared to wild-type plants. Transcriptome profiling further suggested that PtoJAZ10 may synergistically bolster insect resistance and stress tolerance by modulating key genes within the MAPK signaling pathway (e.g., MPK3/6 ) and the phenylpropanoid biosynthesis pathway (e.g., CCoAOMT1 and 4CL ). Collectively, our findings provide a foundation for understanding the role of PtoJAZ10 in poplar defense mechanisms against insect herbivory.