Formation and Function of the Quiescent Center - The Major Regulators

Abstract

Plants can grow indeterminately. The ongoing growth of roots is made possible by the capability of the plant to maintain a pool of stem cells. These stem cells keep proliferating and do not differentiate. The daughters of the stem cells differentiate and form the different structures of the root. In the plant root, stem cells are located in the root tip. The stem cells are located in an organized structure, the stem cell niche. The stem cell niche functions as a microenvironment where, by short range cell signaling, the stem cells are maintained. The Quiescent Center (QC) lies in the centre of the root stem cell niche and provides the signals for maintenance of the surrounding stem cells. The organization of the niche is set up early in embryogenesis and stays unchanged in the mature plant. Essential for root patterning in embryogenesis is the phytohormone auxin. Several transcription factors are involved in both root patterning in the embryo and stem cell maintenance in the mature plant. The processes of organization and maintenance of root stem cells are very well studied in the Arabidopsis thaliana and new insights from this model organism will be discussed here.