1. Department of Plant Biology; University of Navarra; Pamplona, E-31008 Spain
2. Department of Plant Biology; University of Barcelona; Barcelona, E-8028 Spain
3. Agrobiotechnology Institute; Public University of Navarra; Mutilva Baja, E-31192 Spain
4. Department of Soil Microbiology and Symbiotic Systems; Zaidin Experimental Station (CSIC); Granada, E-18008 Spain