Primordium
Genes including STM (shoot meristemless) and CUC (cup-shaped cotyledon) are involved in defining the borders of the newly formed primordium.
[citation needed] Primordia initiation is the precursor for the start of a primordium, and typically confers new growth (either flowers or leaves) in plants once fully mature.
[11] There is a lot of current research being conducted to explain the role that it assists in the process of plant primordium.
It is believed to control these processes by binding to a specific receptor on plant cells and influences gene expression.
The subsequent accumulation of cell division and enlargement in this bundle of tissue gives rise to a new structure known as the root primordium.
One method used to test the theory that PUCHI is responsible for LRP development, was by using Arabidopsis Thaliana accession col as the wild type (WT) strain, and isolating the PUCHI-1-mutant from the T-DNA insertion.
The function of the PUCHI gene was demonstrated by using the PUCHI-1 mutant (using Arabidopsis Thaliana as the model plant), which if backcrossed three times to Arabidopsis Thaliana accession col (WT), it was demonstrated to affect lateral root and flower primordium development by stunting LR growth.
[17] One of the many theories out there, is that Auxin promotes downstream PUCHI expression via a cascade signaling effect, by triggering ARF and Aux/IAA protein functions.
PUCHI genes act as a transcriptional regulator of lateral root primordium development by controlling its cell division during this stage.
[19] Signals propagated in the epidermis initiate primordia growth in directions away from the cotyledons (in dicotyledonous plants) in simple patterns, known as phyllotaxis.
[20] Phyllotactic patterns determine plant architecture and the positions of where new leaves will develop can be easily predicted by observing the locations of existing leaf primordia.
Phyllotactic spiral patterns, as observed in Arabidopsis, have an unequal auxin distribution between left and right sides, resulting in asymmetrical growth of leaf laminas.
[22] Once in the meristem, developing organ primordia act as a sink, absorbing and depleting auxin from the surrounding tissue.
