Role of the plasma membrane H+-ATPase PHA1 during tuberization in Solanum tuberosum L.

MUÑIZ GARCÍA, MARÍA NOELIA; SCHLESINGER, MARIANA; CAPIATI DANIELA ANDREA; STRITZLER, MARGARITA; BARRERA JULIETA BELEN; CORTELEZZI JUAN IGNACIO; FUMAGALLI MARINA

Buenos Aires

Simposio; Frontiers in Bioscience 3; 2018

IBioBA, CONICET - Partner Institute of the Max Planck Society

Plasma membrane (PM) H+-ATPases are integral membrane proteins that pump protons out of the cell, generating an electrochemical gradient of protons across the plasmalemma. This process contributes to the maintenance of pH and drives the secondary transport of ions and metabolites. PM H+-ATPases are involved in several physiological responses, such as cell expansion, phloem loading/unloading, stress adaptation, and plant growth and development. Seven PM H+-ATPase genes were identified in the Solanum tuberosum genome. Studies using PM H+-ATPase inhibitors showed that PM H+-ATPases are involved in tuberization, acting at different stages of the process. This study presents the characterization of the proton pump PHA1 in potato. Transgenic potato plants overexpressing PHA1 were generated (35S::PHA1) to determine the physiological role of this particular isoform focusing on the role in stolon and tuber development. At early developmental stages, 35S::PHA1 stolons elongate faster and show longer epidermal cells than wild-type stolons; this accelerated growth is accompanied by higher cell wall invertase activity, lower starch content, and higher expression of the sucrose?H+ symporter gene StSUT1. 35S::PHA1 stolons display an increased branching phenotype and develop larger tubers. 35S::PHA1 plants are taller and also present a highly branched phenotype. These results reveal a prominent role for PHA1 in plant growth and development. Regarding tuberization, PHA1 promotes stolon elongation at early stages, and tuber growth later on. PHA1 is involved in the sucrose?starch metabolism in stolons, possibly providing the driving force for sugar transporters to maintain the apoplastic sucrose transport during elongation. 35S::PHA1 plants grown in soil also develop larger tubers and show an increased tuber yield with respect to wild-type plants, suggesting that the PHA1 gene might be a potential tool to increase potato crop yield.