Functional analysis of a putative master regulator of plant development, the Translationally-Controlled Tumour Protein [article]

Remi Branco, University, The Australian National
2020
Being sessile, plants need to accurately coordinate leaf and root growth to adapt to changing environmental conditions. TCTP (Translationally Controlled Tumour Protein) belongs to a conserved gene family, present in all eukaryotes. In animals, TCTP controls several core cellular processes including apoptosis, cellular proliferation and growth, tissue patterning, and is thought to interact with the TOR (Target Of Rapamycin) pathway. Plant TCTPs are little known, however, but recent studies
more » ... ecent studies suggest functional similarities with animal TCTPs. What functions they assume is still a matter of debate and how they promote organ and whole organism growth is controversial, although they are widely described as mitotic activators, but with no role in cellular growth. In addition, plant TCTPs have never been shown to have extracellular functions and act as signalling molecules as known of animal TCTPs. This Thesis investigates TCTP function in plant development. Using Arabidopsis as a model plant species, and focusing on AtTCTP1, I probe the role of AtTCTP1 in the expansive growth of non-proliferative cells; I explore the AtTCTP1 molecular pathway in the control of root elongation and embryogenesis; and I investigate the physiological relevance to root development of AtTCTP1 mRNA and protein mobility. To fulfil these aims I carried out a kinematics analysis of primary root and hypocotyl development. This included the development of a custom imaging and bioinformatic pipeline for in situ, high throughput acquisition of spatial profiles of cell sizes and expansion rates. The results demonstrate that AtTCTP1 acts in the positioning of frontiers between proliferating, expanding only, and maturing cells in roots; controls cell size at division, hence the balance between expansion and partitioning rates in meristematic cells; and promotes the growth and final size of non-proliferative cells, in the root elongation zone and also the hypocotyl, indicating this is a likely a general function. Supporting this, TCTP1 also promotes tip g [...]
doi:10.25911/5f6b247368978 fatcat:leebjmc6vvdhdo2egkh442mfge