The catalytic subunit c2b of protein phosphatase 2A (StPP2Ac2b) regulates tuber sprouting in Solanum tuberosum Spunta

MUÑIZ GARCÍA MARÍA NOELIA; GROBLY IARA MARLENE; CORTELEZZI JUAN IGNACIO; FUMAGALLI MARINA; ANDREA CAPIATI, DANIELA

Congreso; XXXIII Argentinian meeting of Plant Physiology (RAFV2021); 2021

Once harvested, potato tubers go through a period in which their buds are not able to grow, called dormancy, whose duration depends on genetic and environmental factors and is mainly controlled by hormonal balance. The concentration of abscisic acid (ABA) increses after harvest, inducing and maintaining dormancy. However, its levels decrease during tuber storage, while the levels of gibberellins (GA) and cytokinins increase, triggering thereactivation of dormant meristems. Tuber dormancy break implies a rearrangement of sugar metabolism, from a reserves-synthesis metabolism to its degradation. Initially, tuber soluble hexoses and sucrose transported to the shoot initiate the dormancy break. But then tuber starch degradation will support the supply of energy to the developing shoot, where sucrose after being transported and hydrolyzed will be used to sustain growth. Serine/threonine protein phosphatase type-2A (PP2A) are involved in several physiological processes in plants. We developed potato plants overexpressing the catalytic subunit c2b (StPP2Ac2b) under the transcriptional control of the 35S promoter (StPP2Ac2b-OE). In thiswork the role of StPP2Ac2b in potato tuber dormancy and sprouting was studied. Sprouting progression, variation of glucose, sucrose and starch levels, as well as invertase and amylase activity and the expression levels of genes controlling the balance of ABA/GA hormones were evaluated. StPP2Ac2b overexpression delays the start of tuber sprouting and modifies the sprout growth pattern, by a mechanism involving changes in the regulation of sucrose/starch metabolism as well as GA/ABA balance. These results point out that PP2A is involved in the signaling and regulation of tuber dormancy and shoot growth.