Growth of aerial roots with an extensive elongation zone by the example of a hemiepiphyte Monstera deliciosa

Abstract

We investigated peculiarities of growth of aerial roots in a hemiepiphyte Monstera deliciosa. Aerial roots show low absolute and relative rates of growth and have an extensive elongation zone. In contrast to common roots, cell elongation in the elongation zone of aerial roots may last for 30 days and sometimes longer. The length of cortex cells increases in direct proportion to the distance from the root tip. This means that there is no drastic change in the relative rate of growth associated with transition to elongation characteristic of common roots. Distribution of growth over the elongation zone of aerial roots is irregular. Within the elongation zone, the cells of rhizodermis can divide, and divisions are distributed nonuniformly. The contact between neighboring growing polycytes (cell complexes) is presumably associated with their sliding against one another (intrusive growth). By the example of aerial roots of Monstera deliciosa, we showed a particular type of growth organization in the root with an extensive elongation zone differing from the growth of common roots and resembling the growth of leaves, stems, and fleshy fruit of dicotyledons.