S19 - Session O1 - Genome-wide analysis of G-type lectin genes family in Fragaria vesca and functional characterization of FaMBL1 gene in defense response of F. × ananassa to fungal pathogens

Authors: Francesca Negrini *, Lijing Ma, Zeraye Haile Mehari, Silvia Sabbadini, Bruno Mezzetti, Elena Baraldi

Strawberry ( Fragaria × ananassa ) is one of the most consumed and produced fleshy fruits in the world but due to its characteristic softening is highly susceptible to many fungal pathogens. Anthracnose and gray mold are two of the most destructive diseases of strawberry which lead to serious fruit rot. As it is known, white unripe strawberry fruits are more resistant to Colletotrichum acutatum than red ripe fruits. Previous transcriptional analysis conducted during early stage infection has shown that a mannose-binding lectin gene FaMBL1 was the most upregulated in the white stage compared to the ripe susceptible one. FaMBL1 belongs to the G-type lectin family, which has important roles in plant development and defense process. In this study genome-wide identification of G-type lectin gene family was carried out in F. vesca. Overall, 133 G-lectin genes were characterized for domain arrangement andexpression patterns. Active transcription of G-lectin genes during development and under stresses suggested a potential role of G-lectin genes in strawberry defense. Hence, stable transgenic strawberry plants overexpressing the FaMBL1 gene were generated. Transformed strawberry plants were selected and molecularly characterized through droplet digital PCR and RT-PCR analysis. In total four overexpressing lines (OE) with different copy numbers were obtained and used for the subsequent studies, including the evaluation of disease-related phytohormones content and their reaction to biotic stresses. Accordingly, jasmonic acid (JA) was found decreased in OE-lines compared to wild type (WT). Furthermore OE-plants petioles inoculated with C. fioriniae had lower disease incidence than WT, and leaves challenged by B. cinerea showed remarkably smaller lesion. Furthermore, expression of defence related genes as chitinase 2-1 ( FaChi2-1 ) gene showed higher expression in OE-lines than in WT during B. cinerea infection development. Our results showed that G-type lectin genes, a big gene family in F. vesca , are involved in strawberry response to biotic and abiotic stresses, and in particular, FaMBL1 gene plays a role in inducing disease resistance, presumably in a JA-dependent pattern.