Cytology Study On Callus Formation Of Camptotheca Acuminata

This article is aimed to study the callus formation of the leaves and semi-woody branches of Camptotheca acuminata .The optical microscope and transmission electron microscope were used in this study. The study shows:Culturing the leaves from the seedling of Camptotheca acuminata at different developmental stages indicated that there was not much difference in callus formation, normally it was around 10 days and the shape, texture, physiological features of the callus were similar, and the callus was white and easy to be separated.The microscopy structure showed: The cell division started one day after the leaves were cultured, the cells from the leaf cut were the first to enter the cell division, then the cell division expanded gradually to the rest of the tissue. The cells underwent mitosis and the callus originated from the cells located in the mesophyll.The ultrastructure showed: During the dedifferentiation of the explant of the Camptotheca acuminata leaves, large amount of starches accumulated in the chloroplast, the level of starches in substratum increased gradually;during the callus formation, the chloroplast formed proplastid buds and proplastid, it was considered the intermediate stage of the mesophyll cells' dedifferentiation. During the callus formation, the mitochondrion, rough endoplasmic reticulum distributed around the chloroplast and plasma membrane;they were fairy large in quantity. The cytoplasm gradually reduced during the callus formation and the intercellular r space increased gradually, the intercellular space was schizogenous intercellular space.In the process of cutting propagation of the semi-woody branch of Camptotheca acuminata, the callus formed above the cut didn't differentiate into root. But adventitious roots developed, and these were originated from the original root body, formed in the vascular cambium and bast tissue, also in the vascular ray crosswise. The original root body differentiated into root primordiu, the root primordiu extended inward and connected with the vascular tissue;extended outward, the root primordiu broke through cortex and periderm, and formed adventitious roots. There were discontiguous sclerenchymatous cells between the cortex and vascular tissue of the caulicle of Camptotheca acuminata, it did not effect the development of the adventitious roots.