Doctorate thesis of National Institute of Further Education in Agricultural Science

Thursday, March 8, 2018

 

Study of the physiological and molecular mechanisms of co-regulation of phosphate and zinc homeostasis in plants

Mushtak Kisko
BPMP, “Hormones, nutrients and development” team

 

Jury :
Hatem ROUACHED, CR1, INRA, BPMP Montpellier (Thesis Director)
Stéphane MARI, Chargé de Recherche, INRA, BPMP Montpellier (Examinateur)
Sébastien THOMINE, Directeur de Recherche, CNRS Gif, établissement (Rapporteur)
Moez HANIN, Professeur, Centre de Biotechnologie de Sfax (CBS) & Institut Supérieur de Biotechnologie (Rapporteur)

 

Abstract :
In plants, while it is clear the homeostasis of different nutrients is highly dependent on each other, they are usually studied independent of each other. Given the paucity of past studies assessing the biological significance of mineral nutrient homeostasis interaction, very little is known about the genetic and molecular basis of such interactions. During my thesis, we made significant progress in going towards a more integrative comprehension of the problem and identify the molecular and genetic bases for a highly important and conserved nutrients interaction: the interaction of zinc and phosphate. First, using the phosphate transporter PHO1;H3 as entry molecular point, and by combining system biology and functional genomics approaches we have identified the functional module (four transcription factors) that regulates the expression and activity of PHO1;H3 under Zn deficiency leading to control Pi accumulation in shoots. Second, following our discovery of Lyso PhosphatidylCholine (PC) AcylTransferase 1 (LPCAT1) using genome-wide association studies (GWAS), we determined complete molecular pathway controlling the expression of this gene. We further uncovered a fundamental link between phospholipid metabolism and Pi-Zn homeostasis interaction via LPCAT1, which lays the foundations to explore a new role for Lyso-PC and PC in control of macro- and micronutrients homeostasis interaction. Taken together, our discoveries offer a new perspective on how to improve Pi content in plants, as our findings suggests that modulating the Zn-deficiency signalling pathway might be a good and simple approach for that.