Lipoxygenase localisation in strawberry fruits

Lipoxygenases (LOX E.C.1.13.11.12) are a family of nonheme-iron-containing fatty acid dioxygenases that are ubiquitous in plants and animals. These enzymes catalyse the oxygenation of polyenoic fatty acids which contain the (1Z,4Z)-pentadiene system, to produce conjugated diene hydroperoxy fatty acids (HPO) (Varvas et al 1999 J Biol Chem 15; Feussner & Wasternak 2002 Annu Rev Plant Biol, 53). HPO are then metabolised via several secondary pathways to form a plethora of bioactive compounds collectively called oxilipins. In plants, oxilipins are reported to be related either to development or to the stress involved in wound healing, pest resistance or signalling, and they also seem to have antimicrobial and antifungal functions. In strawberry, LOX activity increases during receptacle ripening and highly reactive hydroperoxides are produced as a consequence, these load in part, to volatile aldehydes and alcohols biosynthesis which are putative signalling molecules thought to mediate plant-plant as well as plantinsect interaction (Leone et al 2002 Hort Acta, in press).The temporal and spatial expression of LOX during berry ripening seems to be of fundamental importance in providing clues as to the physiological function of various LOXs and LOX-derived products. In this study, histological and intracellular localisation of LOXs was detected by immunofluorescence using anti-LOX antibody and AntiIgG-AlexaFluor688 conjugated. Analyses of strawberry fruit sections, by confocal laser scanning microscope, showed labelling associated to membranes and lipid bodies in receptacle tissue, may be related to the modification and remodelling of the endomembrane system during ripening. LOX accumulation was also detected inside the achenes during strawberry fruit ripening.