Heterologously expressed protein phosphatase calcineurin downregulates plant plasma membrane H+-ATPase activity at the post-translational level.
To investigate the effects of calcineurin expression on cellular ion homeostasis in plants, we have obtained a transgenic cell culture of tomato, expressing constitutively activated yeast calcineurin. Transgenic cells exhibited reduced growth rates and proton extrusion activity in vivo. We show that reduction of plasma membrane H+-ATPase activity by expression of calcineurin is the basis for the observed phenotypes. Transgenic calli and cell suspensions displayed also increased salt tolerance and contained slightly higher Ca2+ and K+ levels. This demonstrates that calcineurin can modulate ion homeostasis in plants as it does in yeast by affecting the activity of primary ion transporters.
Departamento de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín, Apartado 419, 18008 Granada, Spain.
Mari Carmen
MC
Marín-Manzano
Maria Pilar
MP
Rodríguez-Rosales
Andrés
A
Belver
Juan Pedro
JP
Donaire
Kees
K
Venema
D019703:Calcineurin / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology*; D002478:Cells, Cultured; D015536:Down-Regulation; D018506:Gene Expression Regulation, Plant; D007477:Ions / Q000032:analysis; D018551:Solanum lycopersicum / Q000235:genetics / Q000378:metabolism; D063245:Plant Development; D010944:Plants / Q000235:genetics* / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011499:Protein Processing, Post-Translational; D006180:Proton-Translocating ATPases / Q000378:metabolism*
D007477:Ions; D019703:Calcineurin; D006180:Proton-Translocating ATPases