Abstract: 【Objective】 The encoding geraniol 8-hydroxylase （G8H） gene OjG8H in the tissues of Liyang white celery was obtained through cloning,and a preliminary functional analysis of it was carried out.The objective of this study was to provide reference point for further research on the potential function of OjG8H gene in the biosynthesis processes of cellulose,lignin and flavonoids,as well as for the variety improvement of Liyang white celery.【Method】Using the hollow Liyang white celery and its mutant solid Liyang white celery as experimental materials,the contents of cellulose,lignin and flavonoids were determined.OjG8H gene was cloned,and bioinformatics analysis was conducted on its sequence and the encoded protein.Real-time fluorescence quantitative PCR was used to detect the relative expression of the OjG8 Hgene in the stems,petioles and leaves of the hollow and solid Liyang white celery.The correlation between the contents of cellulose lignin and flavonoids in these tissues and the relative expression level of OjG8H gene was analyzed. 【Result】 There were obvious differences in the cross-sections of the stems and petioles between hollow and solid Liyang white celery.The contents of cellulose and flavonoids in the leaves of the 2 Liyang white celery were significantly higher than those in the stems and petioles （P＜0.05,the same below）.The lignin content in the stems and petioles of the hollow Liyang white celery was significantly higher than that in the leaves,while the lignin content in petioles of the solid Liyang white celery was significantly higher than in the stems and leaves.The total length of the 2 Liyang white celery OjG8H gene was 1494 bp,and there were differences at site 75 and site 416.At site 75,the base of hollow Liyang white celery was adenine （A）,while that of the solid Liyang white celery was thymine （T）.At site 416,the base of the hollow Liyang white celery was T,and that of the solid Liyang white celery was A.The OjG8H gene CDS sequence of hollow and solid Liyang white celery both encoded 497 amino acid residues.The 25^th amino acid at the C-terminal was glutamine （Q） in the hollow Liyang white celery and histidine (H) in the solid Liyang white celery.The 139^th amino acid was valine（V） in the hollow Liyang white celery and aspartic acid （D） in the solid Liyang white celery.The OjG8H protein was a stable hydrophilic protein and its subcellular localization was in the endoplasmic reticulum,with 1 transmembrane region.The OjG8H protein had a relatively close genetic relationship with the G8H of Daucus carota,which also belonged to the Apiaceae family.The relative expression level of OjG8H gene in the petioles of hollow Liyang white celery was significantly higher than that in the stems and leaves.The relative expression levels of OjG8H gene in the stems and leaves of the solid Liyang white celery were significantly higher than those in hollow Liyang white celery,while it was the opposite in the petioles.There was significant positive correlation between the relative expression level of OjG8H gene in Liyang white celery and the lignin content. 【Conclusion】 The protein encoded by the OjG8H gene belongs to a member of the CYP superprotein family and is tissue specific.This gene may be involved in the synthesis of lignin in Liyang white celery.