组织培养条件下喜树叶片细胞壁酸性降解的pH值观察

喜树叶片外植体经组织培养第13 d和23 d后进行解剖学观察,同时比较正常叶片的解剖学特征,发现在pH值为5.8的酸性培养基中,喜树叶片外植体中的海绵组织和栅栏组织等薄壁细胞相继发生明显的细胞壁降解,而表皮细胞发生较微弱的细胞壁降解现象;进行组织培养前,正常叶片的各类细胞未观察到细胞壁降解现象发生。应用BCECF-AM pH荧光探标记并采用激光共聚焦在480 nm波长下进行pH值测定发现,喜树叶片外植体经组织培养第13 d和第23 d后的海绵组织和栅栏组织等薄壁细胞部位的pH值均为5.2,但表皮细胞部位的pH值则为5.7~5.8,而正常叶片各类细胞的pH值平均为5.7。这说明, pH值为5.8的酸性培养基和喜树叶片薄壁细胞内的酸性成分自泌可能共同诱导了其细胞壁的酸性降解。

Observation on pH variation during cell wall acid degradation in Camptotheca acuminata leaf under the tissue culture condition

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.