Arabidopsis root patterning - Molecular Biology

Arabidopsis thaliana roots have a very characteristic pattern, with well defined and morphologically distinguishable tissue layers. SCZ (SCHIZORIZA) gene codes a HSF (Heat-Shock Transcription Factor) that was shown to be involved in the patterning of Arabidopsis thaliana roots.

Single point mutations in SCZ leads to drastic changes in the root morphology: the QC (quiescent centre) that is very clear in WT (wild type) roots is no longer visible, there is an extra endodermal layer (Figure 1A) and the cortical layer starts to develop root hairs, which in WT roots only appears on epidermal cells (Figure 1B). Additionally, analysis of cell identity markers shows that the identity of several tissues were mixed in mutant roots (Figure 1A), and more drastically, there is no longer a tissue layer expressing cortical markers. Altogether these results show that SCZ is necessary for the cortex specification and for the separation of other tissues identities. Through the use of different molecular techniques this project aims to uncover how SCZ is exerting its function on root patterning. Additionally, since SCZ codes a heat-shock transcription factor, another goal of this project is to investigate the role of SCZ in stress response.

Some techniques employed in this project: Golden Gate and Gateway cloning, CRISPR-Cas9 genome editing, yeast-two-hybrid interaction assay, RNA-sequencing, in-situ hybridization and confocal microscopy.

Figure 1 – Defects in scz mutant roots. A) Yellow stars mark the single endodermis layer in wt (wild type) and double layer in scz roots. Blue arrow points to the quiescent centre (QC) that is visible on WT and not distinguishable on mutant. Columella and lateral root cap marker (green) is also expressed in scz epidermis (red). B) White arrow points to the root hair emerging from the layer under epidermis in scz, and the bottom image shows a wt root with hairs emerging only from epidermis.
Figure 1 – Defects in scz mutant roots. A) Yellow stars mark the single endodermis layer in wt (wild type) and double layer in scz roots. Blue arrow points to the quiescent centre (QC) that is visible on WT and not distinguishable on mutant. Columella and lateral root cap marker (green) is also expressed in scz epidermis (red). B) White arrow points to the root hair emerging from the layer under epidermis in scz, and the bottom image shows a wt root with hairs emerging only from epidermis.