STUDIES ON THE PURPORTED ROLE OF ABA IN DEFENSE AGAINST INFECTION WITH XYLOPHAGES AFFECTING GRAPEVINES

ESCORIAZA G.; BERLI F.; COHEN A.; GATICA M.; BOTTINI R.; PICCOLI P.

TARRAGONA, ESPAÑA

Congreso; XX INTERNATIONAL PLANT GROWTH SUBSTANCES ASSOCIATION (IPGSA) MEETING; 2010

INTERNATIONAL PLANT GROWTH SUBSTANCES ASSOCIATION (IPGSA), PLANT GROWTH REGULATION SOCIETY OF AMERICA (PGRSA) AND THE JAPANESE SOCIETY FOR THE CHEMICAL REGULATION OF PLANTS (JSCRP)

The grape disease hoja de malvón, an important problem of the Argentine`s vineyards, is associated with a fungi complex which includes Phaeoacremonium parasiticum. Some studies report that fungi-produced ABA increases the plant susceptibility to pathogens, while others claim that plant-produced ABA promotes resistance. The aims were to determine: i) the ability of P. parasiticum to produce ABA, ii) ABA levels in grape plants infected or not with the fungus, iii) the effect of ABA in infected plants. When ABA content was analyzed in P. parasiticum cultures in Czapek medium only traces of ABA were detected by GC-EIMS. Fungal infection did not affect ABA levels of in vitro plants cv. Chardonnay at 7 and 14 days, but after 30 days doubled the ABA amount in leaves (i.e., 893 ng.gFWt-1 vs. 475 ng.gFWt-1). Plants were then inoculated and/or treated with 0 to 50 µM ABA. After 7 days the fungus did not affect FWt, number of leaves, plant height and chlorophyll content (Chl), but augmented levels of compounds absorbing at 305 nm (Abs 305) and malondialdehyde (MDA). At day 14, the fungus also diminished number of leaves and plant height. ABA alone did not affect FWt, Chl, MDA and Abs 305, but it reduced number of leaves and plant height though differences disappeared at day 14. ABA did not reverse the fungus effect for none of the parameters assessed. We conclude that ABA plays no role in defense against infection with P. parasiticum, neither increases the plant susceptibility to the fungus.