Plant mitochondria. Fifty years of plant biology.

This history has its conventional opening about twenty years after the statement of the "Cell Theory", when, at the end of the 19th century, several cytologists discovered unusual, minute corpuscles in the protoplasm of both animal and plant cells. These organelles, owing to their polymorphism, were defined "mitochondria" and a pressing debate on their function and origin went on for about half a century. The invention of the electron microscope and the development of a technique of differential fractionation permitting the separation of the cell constituents, made it possible to connect the structure and function of mitochondria and to attribute to them the role of the site of the aerobic respiration. Research on plant mitochondria got a great step forward in 1951, when the American group of James Bonner demonstrated that mitochondria of mung bean accomplished the whole TCA cycle coupled with the oxidative phosphorylation. One of the fundamental phases of that immense cycle of reactions represented by the metabolism of plant cell had thus its completion.