Differential pathogenic response in strawberry tissues and organs by colletotrichum acutatum

Abstract

The susceptibility of different tissues and organs from strawberry plants, cv “Camarosa”, to Colletotrichum acutatum was tested using a severity index based on infection response. Symptoms developed on inoculated tissues were characterized along 30 days. Flowers, except sepals, petioles and fruits were the most susceptible organs to the pathogen and they became necrotic tissues at 30 days post inoculation (dpi). Also, well-developed acervuli, which produced masses of orange-pink spores, were observed on these infected organs. An asymptomatic stage or latency phase was observed in green and white strawberry fruits. In spite of they were inoculated anthracnose symptoms were observed only when they became red fruits. On the other hand, strawberry leaves and sepals were resistant to infection by C. acutatum and only small flecks or light brown spots were observed reaching a size of 1 to 5 mm at 30 dpi. Likewise, the susceptibility of stolons and crowns to C. acutatum was evaluated as intermediate at 30 dpi. Finally, the infection process of the fungus on strawberry leaves and petioles was studied using light and electron microscopy. Pre-penetration events were similar on both, leaves and petioles: However, differences between colonization of strawberry leaves and petioles by C. acutatum were observed.