Plant & Animal Genomes XIV Conference Plant & Animal Genomes XIV ConferenceJanuary 14-18, 2006
Town & Country Convention Center
San Diego, CA
José M. Colmenero-Flores , Javier Brumós , Ana Conesa , Guadalupe Sánchez , Pedro Izquierdo , Manuel Talón
Citrus is a major world horticultural commodity, first in terms of volume of world trade (exports and imports). Spain is the most important producer of fresh citrus fruit and, therefore, high fruit quality is of paramount importance for Spanish citrus productivity. However citrus rootstocks like Carrizo citrange, that fulfill sanitary regulations and fruit quality requirements are generally sensitive to abiotic stresses. In particular, salinity is an increasing problem in Spain and other Citrus-producing regions, where this perturbation is clearly detrimental to fruit yield. Our research group is investigating the molecular bases of salt intoxication in Citrus plants. When subjected to NaCl stress, citrus and other woody perennial fruit species show injury symptoms that correlate with Cl-, rather than with Na+, accumulation in the shoot. The greater salt resistance of rootstocks such us Cleopatra mandarin and Rangpur lime is associated with their capacity to limit the accumulation of Cl- in leaves, a salt-resistance mechanism known as chloride exclusion. However Cl- homeostasis in plants has been poorly characterized at the molecular level.
In order to recognize genes responsive to Cl- intoxication in citrus plants, a functional-genomic approach has been employed to compare gene expression between two different rootstocks which differ in their Chloride-exclusion capacity, the poor Cl- excluder citrange Carrizo and the efficient excluder Cleopatra mandarin. To distinguish between ion toxicity associated to Na+ and Cl-, gene expression comparison in response to both NaCl and KCl has also been evaluated.