LEMON FRUITS FROM ENDOCHITINASE TRANSGENIC PLANTS EXHIBIT RESISTANCE AGAINST POSTHARVEST FUNGAL PATHOGENS

Constitutive over-expression of antifungal genes from microorganisms involved in plant defence mechanisms represents an efficient strategy to confer genetic resistance against a broad range of phytopathogenic fungi. In lemon (Citrus limon (L.) Burm. f.), fungal diseases cause economic losses in the field as well as in postharvest management. In this study, fruits collected from two different transgenic lemon clones (E23 and E24) expressing a chitinase gene (chit42) from Trichoderma harzianum were tested to investigate the level of resistance against Penicillium digitatum, P. italicum, Colletotrichum gloesporioides and Botrytis cinerea. Fruits were inoculated with conidial suspensions of these fungi, incubated in a climatic chamber and symptom development was evaluated at 6, 14 and 21 days after inoculation. While fruits from either transgenic clone inoculated with C. gloesporioides and B. cinerea did not show mould symptoms during the whole evaluation period, similar fruits inoculated with P. digitatum or P. italicum showed reduced lesion area (50%) in comparison with the non-transgenic control fruits after 6 days and no difference after 14 days. The transgenic lemon clones, obtained from a highly appreciated lemon cultivar, did not show any difference in morphological and qualitative fruit traits compared to the non-transgenic control. These results suggest that their use could represent an alternative for sustainable management of lemon postharvest diseases.