Here ethylene insensitive mutants fail to show this response, and other mutants display the triple response in the absence of ethylene. Rev. Cell Dev. The STM gene is identified as a shoot meristem-specific one expressed in shoot meristem cells beginning at the late globular stage of embryogenesis. The ANT gene is expressed in the two flanking regions from which the cotyledons are developed. The primary root meristem or RAM is organized both radially and longitudinally along the root axis.
Different mutations alter the primary root in various ways.
In some, the meristem does not develop during the postembryonic phase. In Arabidopsis the two types occur in different cell files. If the epidermis is detached, additional cells differentiate to form root hairs, thus root hair cells are a basic state of differentiation. This gene is known to be negatively regulated in the response to ethylene, and ethylene is known to promote production of root hair cells. The analysis implicates local interactions between cells as a determiner of a hair cell, but all cells in one cell file are either hair cells or non-hair cells.