| The histocytological features and chlorophyll biosynthesis process were studied to illustrate the structural and physiological basis of the chimera variety formation mechanism in Ananas bracteatus. The histocytological observation demonstrated that abundant chloroplasts existed in the cells of green parts of chimeric leaves, while few chloroplast was found in the white parts of chimeric leaves. Furthermore, the chlorophyll contents in the white tissues of chimeric leaves and the complete white leaves were significantly lower than that in the green tissues of chimeric leaves and the complete green leaves. For the white leave tissues of A. bracteatus cv. Lidenii and A. bracteatus cv. Massangeana, the decline of chlorophyll precursors contents occurred in the UroⅢ biosynthesis step . The decrease of chlorophyll precursors contents began from ALA in the complete white plants. Therefore, the albino leaves would be caused by the reduction of chlorophyll biosynthesis metabolism, which can lead to a lower chlorophyll content. |
