Abstract: The explant of Camptotheca acuminata leaf was observed on anatomy after cultivation of 13 day and 23 day, contrasting with normal leaf. In pH 5.8 medium, we observed that the cell wall degradation gradually arised in explants of parenchyma cell including the spongy tissue and palisade tissue in C. acuminata leaf obviously, whereas unconspicuously in epidermis. But before the tissue culture, various types of cell in normal leaf cannot be detected. Using the labeled fluorescence BCECF-AM and laser scanning microscopes mensurated the pH under 480 nm, we found the pH of parenchyma cell both in spongy tissue and palisade tissue are 5.2 in explants of C. acuminata leaf, after tissue culture 13 days and 23 days, and the pH of the epidermis is 5.7~5.8, while the average pH is 5.7 in normal leaf. This indicated the medium of pH 5.8 and the secretory acid component in parenchyma cell in C. acuminata leaf both induced the cell wall degradation.

Key words: tissue culture, Camptotheca acuminata leaf, cell wall acid degradation, pH values