Objective The interactions between plants are of great significance to the formation of ecosystems. This study investigated the genetic regulatory mechanisms of plant interactions at the level of neighboring plant interactions, the smallest unit of intraspecific interactions.

Method Using the natural population of Populus szechuanica var. tibetica as research material, different series numbers were randomly paired and cuttings were planted in pots to investigate the growth dynamic phenotypes of plant height throughout the growing season. Combining SNP marker data from the population, system mapping was performed to locate significant QTLs. GO enrichment analysis and construction of ordinary differential interaction networks were used to analyze the functions of candidate genes.

Result (1) A total of 92 significant loci were mapped, annotating 31 candidate genes. (2) In GO enrichment analysis, biological processes included auxin signaling pathways and abscisic acid signaling pathways, molecular functions included endopeptidase activity and protease activity, and cellular components included respiratory chains and cytochromes. (3) Among the 31 candidate genes, genes 5, 8, 10, 12 and 21 were hub genes in the direct effect network, genes 5, 8, 10 and 13 were hub genes in the indirect effect network, and genes 5, 8 and 13 were hub genes in the epistatic interaction network, with genes 5, 10 and 13 involved in plant immune response and environmental stress response.

Conclusion For neighboring interactions among P. szechuanica var. tibetica, system mapping can screen for interaction-related genetic loci, construct genetic regulatory networks, and mine hub genes, providing a new perspective for analyzing the genetic mechanisms of woody plant interactions.