ANALYSIS OF DEFENSIVE RESPONSES IN POTATO AND TOBACCO PLANTS

BACHMANN SD; GIAMMARIA V; BRAVO-ALMONACID F; ULLOA RM

Mar del Plata

Congreso; XLIII reunión de SAIB; 2007

SAIB

Plants evolved several mechanisms to avoid or resist invasion by a pathogen or insect foraging. This capacity depends on early warning followed by activation of wound/defense-response genes. An increase in cytosolic calcium is a key regulator of many defense pathways triggered and Ca2+-dependent protein kinases (CDPKs) are active players in these processes. In addition, nucleotide diphosphate kinases (NDPKs) expression and tyrosine phosphorylation are enhanced in response to wounding and pathogens. Tobacco and potato plants were exposed to wounding and viral infection with PVX. Viral infections were confirmed with antibodies against viral coat protein. Controls, wounded or infected leaves (local and systemic) were harvested and RNA and proteins were extracted. Semiquantitative RT-PCR assays show that the expression of two potato CDPK isoforms, StCDPK1 and StCDPK2, is upregulated in response to wounding while a similar response was observed with NtCDPK2 in tobacco. Anti-NDPK antibodies against human A and B subunits detected NDPK subunits in control potato soluble extracts; while an anti-phospho-tyrosine antibody detected tyrosine phosphorylation in tobacco and potato extracts. The immunologic assays have been optimised and will be used with protein extracts from treated leaves. Cloning of NDPK is currently being performed by RT-PCR using mRNA from potato leaves.