Over-expression of the Bacterial Phytase US417 in Arabidopsis Reduces the Concentration of Phytic Acid and Reveals Its Involvement in the Regulation of Sulfate and Phosphate Homeostasis and Signaling.

Nibras Belgaroui (1, 2) , Ikram Zaidi (2) , Ameny Farhat (2) , Hichem Chouayekh (2) , Nadia Bouain (1) , Sandrine Chay (1) , Catherine Curie (1) , Stephane Mari (1) , Khaled Masmoudi (2) , Jean-Claude Davidian (1, 3) , Pierre Berthomieu (1, 3) , Hatem Rouached (1) , Moez Hanin (2)

1 BPMP - Biochimie et Physiologie Moléculaire des Plantes
2 CBS - Centre de Biotechnologie de Sfax
3 Montpellier SupAgro - Institut national d’études supérieures agronomiques de Montpellier

Phytic acid (PA) is the main phosphorus storage form in plant seeds. It is recognized as an anti-nutrient for humans and non-ruminant animals, as well as one of the major sources of phosphorus that contributes to eutrophication. Therefore, engineering plants with low PA content without affecting plant growth capacity has become a major focus in plant breeding. Nevertheless, lack of knowledge on the role of PA seed reserves in regulating plant growth and in maintaining ion homeostasis hinders such an agronomical application. In this context, we report here that the over-expression of the bacterial phytase PHY-US417 in Arabidopsis leads to a significant decrease in seed PA, without any effect on the seed germination potential. Interestingly, this over-expression also induced a higher remobilization of free iron during germination. Moreover, the PHY-over-expressor lines show an increase in inorganic phosphate and sulfate contents, and a higher biomass production after phosphate starvation. Finally, phosphate sensing was altered because of the changes in the expression of genes induced by phosphate starvation or involved in phosphate or sulfate transport. Together, these results show that the over-expression of PHY-US417 reduces PA concentration, and provide the first evidence for the involvement of PA in the regulation of sulfate and phosphate homeostasis and signaling.

Mots clés: Phytic acid; Phosphorus; Phytase; Signaling; Sulfate; homeostasis

Mots clés: arabidopsis; acide phosphatique; homéostasie

Domaines: Biologie végétale

Nibras Belgaroui, Ikram Zaidi, Ameny Farhat, Hichem Chouayekh, Nadia Bouain, et al.. Over-expression of the Bacterial Phytase US417 in Arabidopsis Reduces the Concentration of Phytic Acid and Reveals Its Involvement in the Regulation of Sulfate and Phosphate Homeostasis and Signaling.. Plant and Cell Physiology, 2014, 55 (11), pp.1912-24. ⟨10.1093/pcp/pcu122⟩. ⟨hal-01506358⟩