Chitinase isoforms in zucchini leaves treated by Nostoc sp. extract.

Cyanobacteria are components of commercial fertilizers which may interfere with plant physiology, making plants less susceptible to biotic and abiotic stress. A peculiar extract of the Nostoc sp. BEA 0300B demonstrated to induce systemic resistance in zucchini plants against Podosphaera xanthii in previous biological and biochemical assays. The aim of this research was to investigate the behaviour of different chitinase isoforms in zucchini plants treated by foliar application of Nostoc sp. BEA 0300B extract. Chitosan was used as positive control, since it is a well-known resistance inducer, while untreated plants were used as negative control. Nostoc extract (2g/l) was applied by spraying one of the 2 cotiledonar leaves. Total proteins were extracted from untreated cotiledonar leaves sampled after 1, 2 and 3 days from the treatment, and were examined with isoelectric focusing analysis. The specific assay for chitinases showed three isoforms with 4.4, 4.6 and 4.7 isoelectric points that were enhanced by Nostoc treatment, depending on the sampling time.