Influence of UV-C irradiation on expansin and pectin-methylesterase gene expression in strawberry fruit

MARINA A. POMBO; MARCELA C. DOTTO; GUSTAVO A. MARTÍNEZ; PEDRO M. CIVELLO

Pinamar, Argentina

Congreso; XLI Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB).; 2005

The exposure to UV-C delays fruit softening, one of the main factors determining fruit postharvest life. This delay in softening may be caused by changes in the activities of enzymes and proteins involved in cell wall disassembly. Expansins are cell wall proteins involved in fruit softening, while pectin-methylesterases (PME) are cell wall enzymes related to pectin demethylation, and their activity is affected by heating, another physical treatment based on abiotic stress. We analyzed FaPME1 gene expression in irradiated strawberry fruits and also mesured PME activity after treatment. An increase in PME activity immediately after the treatment was found. The expression of FaEXP2, FaEXP4 and FaEXP5 genes was analyzed in the same fruit samples, as well as expansin protein acumulation. For these three genes we found a decrease in expression 4 h after treatment and an increase after 24 h. The decrease in gene expression after treatment correlated with a diminution of expansins.