title: The mannose-binding lectin gene FaMBL1 is involved in the resistance of unripe strawberry fruits to Colletotrichum acutatum.
abstract: The fungal pathogen Colletotrichum acutatum is the causal agent of strawberry (Fragaria × ananassa) anthracnose. Although the fungus can infect strawberry fruits at both unripe and ripe stages, the symptoms appear only on red ripe fruits. On white unripe fruits, the pathogen becomes quiescent as melanized appressoria after 24 h of interaction. Previous transcriptome analysis has indicated that a mannose-binding lectin (MBL) gene is the most up-regulated gene in 24-h-infected white strawberries, suggesting a role for this gene in the low susceptibility of unripe stages. A time course analysis of the expression of this MBL gene, named FaMBL1 (Fragaria × ananassa MBL 1a), was undertaken to monitor its expression profile in white and red fruits at early interaction times: FaMBL1 was expressed exclusively in white fruit after 24 h, when the pathogen was quiescent. Agrobacterium-mediated transient transformation was used to silence and overexpress the FaMBL1 gene in 24-h-infected white and red strawberries, respectively. FaMBL1-silenced unripe fruits showed an increase in susceptibility to C. acutatum. These 24-h-infected tissues contained subcuticular hyphae, indicating pathogen penetration and active growth. In contrast, overexpression of FaMBL1 in ripe fruits decreased susceptibility; here, 24-h-infected tissues showed a high percentage of ungerminated appressoria, suggesting that the growth of the pathogen had slowed. These data suggest that FaMBL1 plays a crucial role in the resistance of unripe strawberry fruits to C. acutatum.
authors.affiliation: Department of Agricultural Sciences (DIPSA), University of Bologna, Viale Fanin 46, Bologna, 40127, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Guidarelli
authors.forename: Lisa
authors.initials: L
authors.lastname: Zoli
authors.forename: Alessandro
authors.initials: A
authors.lastname: Orlandini
authors.forename: Paolo
authors.initials: P
authors.lastname: Bertolini
authors.forename: Elena
authors.initials: E
authors.lastname: Baraldi
mesh_terms: D060054:Agrobacterium; D000595:Amino Acid Sequence; D020231:Colletotrichum / Q000502:physiology*; D004269:DNA, Bacterial / Q000235:genetics; D060467:Disease Resistance / Q000235:genetics*; D031985:Fragaria / Q000166:cytology / Q000235:genetics* / Q000382:microbiology*; D005638:Fruit / Q000166:cytology / Q000235:genetics / Q000382:microbiology*; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D017343:Genes, Plant; D037601:Mannose-Binding Lectin / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional / Q000235:genetics; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology*; D013997:Time Factors
chemical_list: D004269:DNA, Bacterial; D037601:Mannose-Binding Lectin; C036483:T-DNA
keywords: Colletotrichum acutatum; fungal quiescence; mannose binding lectin; strawberry ripening; unripe fruit resistance