The Solanum phureja CDPK family

FANTINO, ELISA; SANTIN, FRANCO; ULLOA, RITA M

Jeju

Congreso; IPMB; 2012

IPMB

Calcium dependent protein kinases (CDPKs) are key components of calcium regulated signaling cascades in plants. CDPKs combine Ca2+ sensing (EF hand motifs) and a responding function (protein kinase activity) within a single protein and have therefore been classified as sensor responders. These kinases translate information encoded in the Ca2+ signatures into phosphorylation events of specific target proteins. In different species, the CDPK family is composed of approximately thirty members that differ in their N-terminal variable (NTV) domain. In potato, six isoforms have been characterized, StCDPK1, 2 and 3 (Raíces et al.,2003; Gargantini et al.,2009 ; Giammaria et al., 2011, Grandellis et al., 2012), StCDPK4 and 5 (Kobayashi et al., 2007) and StCPK1 (Lakatos et al., 1998). An in silico search of the Solanum phureja genome allowed us to identify 21 new isoforms. The presence of these kinases in the S.tuberosum L var.Spunta and var.Desirée and in S.tuberosum ssp. Andigena genomes was confirmed by PCR using specific primers for each isoform. Analysis of chromosome localization and gene structure of the new isoforms was performed. ClustalW alignment of the 27 coding sequences of potato CDPKs with sequences from Arabidopsis thaliana and Oryza sativa CDPKs indicate that the potato isoforms are grouped in 4 subgroups as in rice, wheat and Arabidopsis. Twenty three of the twenty seven potato CDPK isoforms present a Gly in position 1 and a Cys in position 4 or 5 that are potential myristoylation and palmitoylation sites. While ten isoforms present the myristoylation consensus MGXXXT/S, other thirteen presentan Asn in position 3 that could promote their myristoylation (Yamauchietal., 2010). Expression analysis of the identified CDPK isoforms was conducted by semiquantitative RT-PCR using as template a cDNA library from tuberizing stolons or leaves or by one-step PCR using as template RNA from in vitro cultured S.phureja plants and specific primers designed on the NTV domains of each isoform. The expression of twelve isoforms was observed in both tissues while only one was present exclusively in tuberizing stolons