Abstract: This study used tissue-cultured seedlings ofRhododendron seniaviniias the experimental material. The anthrone colorimetry, Kaomas Brilliant Blue G-250 staining and enzyme-linked immunosorbent assay （ELISA） were used to determine the content of soluble sugars, soluble proteins, and the content of growth hormone （IAA）, gibberellic acid （GA3）, and zearalenin riboside （ZR）, respectively. The results showed that no latent root primordia were observed in the stems ofR. seniavinii, suggesting that it is an induced root primordia species. At the base of the tissue culture seedlings, soluble sugar content decreased, due to enhanced cell division and metabolic activity. In contrast, soluble protein content increased. Investigation of the role of endogenous hormones in root primordia formation revealed that changes in the contents of IAA, GA, and ZR followed consistent trends and showed a significant positive correlation with root primordia formation. In the process ofR. seniaviniiroot primordia formation, RS.ARF12, RS.ARF16, RS.ARF18, and RS.ARF4 genes were expressed at higher levels, suggesting their important roles in root primordia formation process.

Key words: Rhododendron seniavinii, root primordia, paraffin section, endogenous hormones, ARF gene family