Radial gradient of the mitochondrial ultrastructure in Pisum sativum L. roots

Abstract

Tissue hypoxia in roots of terrestrial plants in the environment saturated with oxygen is conditioned by the high tissue density and oxygen utilization during the cellular respiration, and it is followed by a gradual decrease in the oxygen concentration from the organ surface. We used this natural model on the example of the main roots of 5-day-old seedlings of Pisum sativum L. growing under well-aerated conditions to study the ultrastructure of mitochondria in tissue with reducing oxygen content. In the direction from the root surface to the endodermis, it was found a gradual increase in the size of mitochondria due to swelling and partial fusion of the organelles. The formation of one dominant invagination led to the appearance of cup-shaped organelles in inner cortex cell layers. Such successive changes in the structure of organelles were called the radial gradient of the mitochondrial ultrastructure under a gradual decrease in the cell oxygen content. It is suggested that the described transformations in the mitochondrial ultrastructure could be an unspecific response to conditions that limit their energy and / or metabolic functions.