Control of cell growth in root hairs

Thesis

During development plant cells acquire different shapes and often these shapes are correlated with their function. To understand how these cell shapes and forms develop, it is necessary to understand the underlying regulatory mechanisms of cell growth. The growth of root hair cells is a good example of cells undergoing localized cell expansion to acquire their final form. In Arabidopsis two bHLH transcription factors RHD6 and its target RSL4 have been identified as key regulators of the initiation and elongation phases of root hair (H) cell development. However in order to obtain a better understanding of this RHD6-RSL4 transcriptional pathway controlling root hair growth, the characterization of the immediate targets of RSL4 is necessary. Here I describe the use of a glucocorticoid inducible expression system coupled with the microarray analysis to identify the direct targets of RSL4. Thirty four putative direct target genes of RSL4 were identified. I assessed the requirement of nine of these genes by characterising the phenotypes of plants homozygous for the loss of function alleles. Plants homozygous for loss of function mutations in AT1G22620/SAC1, AT1G35670/CPK11/CDPK2, AT1G30870/PRX7 and AT5G03540/EXO70A1 (44% of the genes analysed) exhibited defects in root hair growth. Taken together my results not only identified potential RSL4 target genes but also demonstrated that RSL4 controls root hair growth by regulating genes that encode proteins involved in cell signalling, vesicle trafficking and cell wall modification.

Authors: Vijayakumar, P

• Publication date: 2012
• Type of award: MSc by Research
• Level of award: Masters
• Awarding institution: Oxford University, UK
• Language: English
• Keywords: RSL4 gene targets
• Subjects: Comparative developmental genetics (plants)