Deciphering the role of Calcium dependent protein kinases, CDPKs, in stress responses in potato plants.

GROSSI, CME; FANTINO ELISA; SCIORRA, M; SANTIN FRANCO; SEGRETIN MARÍA EUGENIA; ULLOA RITA M

Norwich

Conferencia; Plant Calcium Signalling Conference 2017; 2017

John Innes Center

Calcium-dependent protein kinases (CDPKs) decode calcium (Ca2+) signals and activate different signaling pathways involved in hormone signaling, plant growth, development, and abiotic and biotic stress responses. Data mining of the potato genome allowed us to identify twenty-six members of this family in Solanum tuberosum that can be classified into four groups (I to IV). We characterized three members of group II, StCDPK1/2/3, one member of group I, StCDPK7, and are now analyzing two members of group III, StCDPK22/24 that harbor only three EF-hands in their calmodulin-like domains. RT-qPCR analysis indicated that StCDPK1/2/3 and 7 are ubiquitously expressed in the plant tissues with different levels of expression; however, potato plants harboring the reporter GUS gene under the control of the CDPK promoters proStCDPK1/2/3/7:GUS) show that each gene displays a specific spatiotemporal expression profile. In particular, histochemical analysis indicated that StCDPK1 is strongly associated to the vascular system [1]. StCDPK1/2/3 are predicted to be myristoylated and palmitoylated and both StCDPK1 and 2are associated to the plasma membrane [2]. Regarding StCDPK7, transient expression assays show that this kinase displays a cytosolic/nuclear localization in spite of having a predicted chloroplast transit peptide [3]. StCDPK1/2/3 and 7 encode active protein kinases that are able to phosphorylate syntide-2 and Histone in a Ca2+-dependent way; however, each one displays preference for a specific substrate in vitro: StCDPK1 was able to phosphorylate the auxin transporter StPIN4 [1], StCDPK2 strongly phosphorylates StABF transcription factor [4] and StCDPK3 phosphorylates StRSG and StABF [5], while StCDPK7 phosphorylates StPAL [3].